Progress 10/01/04 to 09/30/05
Outputs
1. What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? What does it matter? Greenhouse-grown floricultural crops are constantly being threatened by the plant pathogenic fungus Botrytis cinerea, which causes gray mold or Botrytis blight. The wet, humid greenhouse environment favors rapid growth and prolific sporulation of B. cinerea. Many important floricultural crops are susceptible to Botrytis, with certain plants and plant parts being highly susceptible and the age of the plants also playing a factor in infection. Thus, Botrytis infection can occur as leaf spots; blighting; stem cankers; rots of corms, rhizomes, tubers and seeds; and pre- or postemergence damping off. Botrytis blight continues to cause significant losses at all stages of floriculture production, including seed, plug, bedding plant or potted plant production, stock plant and cuttings production, and
storage and/or shipment of cuttings and cut flowers. Botrytis conidia can be released into the greenhouse atmosphere during any grower activity which disturbs the plants, including irrigating, spraying pesticides, and harvesting cuttings. Natural conidia release occurs approximately midmorning and midafternoon and coincides with a rapid decrease in relative humidity. A conidium may survive for at least three weeks before germination, and may potentially be shipped from greenhouse to greenhouse. Failure to control Botrytis at one production stage in any crop can have negative ramifications for subsequent stages and other susceptible crops in the same facility. Development of resistance in B. cinerea to certain classes of fungicides can complicate choosing an effective control strategy. Phytophthora crown and root rot of ornamentals is caused by Phytophthora spp., a fungal-like organism that produces sporangia which releases swimming spores upon immersion in water. Sporangia likely
play a major role in epidemics, spreading disease from initial points of infection. The seriousness of the problem due to Phytophthora infection varies according to production facility. We have characterized Phytophthora epidemics, and the damages ranged from relatively minor (infection confined to limited foci) to quite serious (50-60% of the grower's production lost to Phytophthora, with a value in excess of $200,000). A better understanding of which Phytophthora spp. are causing problems and how the populations are distributed in space and time provides useful information for developing management strategies. There have been cases of Phytophthora spp. developing resistance to metalaxyl/mefenoxam fungicides. Poinsettias continue to account for the largest value of wholesale potted flowering plant sales for the state of Michigan and the U.S., and the national value of the crop has been steadily increasing. Poinsettia scab (causal agent, Sphaceloma poinsettiae) is a fungal disease
that is spread by water, and since its discovery in the early 1940s in Florida and Hawaii, it has become the limiting factor in the outdoor production of poinsettias in tropical areas of the U.S. The pathogen causes lesions on the stems, leaves and petioles of poinsettias, rendering the plants unmarketable. In severe cases, defoliation, girdling or elongation of stems may occur. Virtually no research has been conducted on the epidemiology of this fungus due to the fact that scab has been managed successfully in the past by use of clean stock plant materials. The recent shift in poinsettia stock plant production to Central America, where the pathogen is indigenous, has resulted in outbreaks of scab in U. S. greenhouses. Growers in the U.S. need management strategies for this new disease of poinsettias to produce a quality crop for consumers. The overall objectives of this research are to: 1) develop durable strategies and technologies for integrated management of Phytophthora
crown and root rot diseases and Botrytis and Sphaceloma flower, leaf and stem blights; and 2) develop new, more effective repellants to protect ornamental plantings from feeding damage by deer and rodents. The plant disease research relates to National Program (NP) 303 (Plant Diseases) and represent contributions to research components I (Identification and Classification of Pathogens), II (Biological Control), III (Cultural Control) and IV (Pathogen Biology, Genetics, Population Dynamics, Spread, and Relationships with Hosts and Vectors). The mammalian herbivore research relates to National Program 304 (Crop Protection and Quarantine), component V (Pest Control Technologies). 2. List the milestones (indicators of progress) from your Project Plan. 1) Plant Disease Research a. Identify the major Phytophthora spp. affecting floriculture production and determine which aspects of Phytophthora's life history contribute significantly to control failure. b. Determine the role of
environment in the disease cycle of B. cinerea and investigate environmental manipulation as a viable management tool for flower and leaf blight. c. Determine the role of the environment in the disease cycle of S. poinsettiae. d. Develop durable production strategies for preventing and eliminating disease caused by Phytophthora spp., B. cinerea, and S. poinsettiae on floriculture hosts. e. Screen novel agents for their potential as management tools for control of Phytophthora crown and root rot disease, Botrytis flower and leaf blight, and poinsettia scab. 2) Mammalian Herbivore Research (FY 2002-FY 2003) a. Isolate and identify natural compounds from browse-resistant plant species, and bioassay these compounds for deer and rabbit repellency. b. Evaluate most promising repellents for phytotoxicity. c. Develop efficacious repellent formulations that resist breakdown by the environment and/or release active ingredients slowly to provide practical, long-lasting plant protection.
3a List the milestones that were scheduled to be addressed in FY 2005. For each milestone, indicate the status: fully met, substantially met, or not met. If not met, why. 1. 1a. Identify the major Phytophthora spp. affecting floriculture production and determine which aspects of Phytophthora's life history contribute significantly to control failure. Isolate, identify and characterize Phytophthora spp. from diseased plants, including fungicide sensitivity. Investigate the occurrence of Phytophthora disease in floriculture production facilities. This milestone was fully met in 2003 and the outcome was published in Plant Disease. Monitoring and processing of samples from growers has continued throughout this project (see question 4b). Milestone Fully Met 2. 1b. Determine the role of environment in the disease cycle of Botrytis cinerea and investigate environmental manipulation as a viable management tool for flower and leaf blight. Quantify the influence of the environment
(temperature, relative humidity, and duration of leaf wetness) on the infection, colonization, and reproductive processes of Botrytis. This milestone was fully met and was expanded to include the response of these infection processes in the presence of fungicides (see 4b). Milestone Fully Met 3. 1c. Determine the role of the environment in the disease cycle of S. poinsettiae. Determine minimum leaf wetness duration needed for infection by observing symptoms 14 days after inoculation and: (a) varying the length of leaf wetness intervals, (b) once the minimum time is determined, varying the temperatures as needed. Monitor the effects of the greenhouse environment on production of conidia of Sphaceloma by placing a Burkard volumetric spore sampler and a WatchDog data logger in a polyethylene hoop greenhouse with 300 "Freedom Red" poinsettias. This milestone was substantially met (see 4b). Milestone Substantially Met 4. 1d. Develop durable production strategies for preventing and
eliminating disease caused by Phytophthora spp., B. cinerea, and S. poinsettiae on floriculture hosts. Research results will be integrated into disease management recommendations, presented at meetings and trade shows, and published in refereed journals as appropriate. This milestone was fully met. Milestone Fully Met 5. 1e. Screen novel agents for their potential as management tools for control of Phytophthora crown and root rot disease, Botrytis flower and leaf blight, and poinsettia scab. Efficacy trials will continue to test unregistered products for disease control, with emphasis on reduced risk fungicides and biopesticides. This milestone was fully met (see 4a & 4b). Milestone Fully Met 3b List the milestones that you expect to address over the next 3 years (FY 2006, 2007, and 2008). What do you expect to accomplish, year by year, over the next 3 years under each milestone? This project is currently operating in its fifth year and is scheduled to terminate September 19,
2005. 4a What was the single most significant accomplishment this past year? New biopesticide found effective as a management tool for control of Botrytis foliar blight. We have been testing Endorse 2.5WP since 2002 for efficacy against Botrytis blight. This biopesticide (active ingredient, polyoxin D zinc salt) again proved especially effective against this disease in our FY 2005 trials. Fungicides are an important component of disease control for growers. Identifying alternatives to B2 carcinogenic fungicides reduces potential harm to growers, consumers and the environment. Using these new products in rotation with others reduces the potential development of fungicide resistance in B. cinerea. 4b List other significant accomplishments, if any. Phytophthora spp. affecting floriculture production characterized. Prompt identification and characterization of the Phytophthora spp. infecting growers' crops is needed to maximize disease control programs. To accomplish this, monitoring
and processing of diseased samples from growers has continued throughout this project. In particular, we have partnered with Diagnostic Services on the campus of Michigan State University to provide screening for fungicide sensitivity of pathogen samples submitted by growers. As a result of this testing, growers received full information regarding the most effective means of disease control. Poinsettia leaf clearing technique developed. A clearing technique was developed for poinsettia leaf tissue. Leaf tissue must be transparent (cleared of all pigment) for fungal spores to be observed microscopically. A new leaf clearing technique was needed because the latex in poinsettia complicates the clearing process, and chloral hydrate, a chemical used in previously published techniques, is a controlled substance that requires a permit for use. Research found that immersion in a 1:1 solution of 95% ethanol and 1M potassium hydroxide at room temperature for two hours or immersion in a
heated solution for 2 seconds successfully cleared poinsettia leaf tissue of chlorophyll and latex. Using this technique on inoculated poinsettia leaves after varying a) the time leaves remain wet and b) the temperature during the wetness period allows determination of minimum leaf wetness duration and optimum temperature for successful infection of poinsettia by S. poinsettiae. Mechanism of spread of poinsettia scab pathogen identified. Effects of relative humidity versus water splash on the scab disease cycle were investigated in a humidity chamber in a greenhouse. It was determined that high relative humidity alone was not enough to prompt spore dispersal of S. poinsettiae from diseased to uninoculated plants; however, splashing water, as occurs during routine watering of plants, did disperse spores and caused new infection sites to arise on uninoculated poinsettias. These findings have an impact on cultural recommendations for poinsettias. Overhead watering could exacerbate
epidemics of scab, whereas drip irrigation would minimize spore dispersal of Sphaceloma. Environmental effects on host infection and colonization by Botrytis cinerea determined. Knowledge of the infection process can allow growers to manipulate the greenhouse environment to manage disease by targeting the pathogen at a vulnerable stage. Geranium leaf disks were inoculated with B. cineria spores and incubated under saturation conditions in moist chambers at varying temperatures and lengths of time and then examined microscopically. Optimum temperature for Botrytis growth was determined to be 16DGC. At this temperature, few conidia germinated within 3 hours, most germinated within 6 hours, and time periods greater than 6 hours supported elongation of germ tubes and formation of infection structures (appressoria). Based on this research, it is recommended that growers keep susceptible plants as dry as possible. If plants remain wet for more than 6 hours, growers should apply a
systemic rather than a protectant fungicide for Botrytis management. Effects of fungicides with differing modes of action on the Botrytis infection process determined. Knowledge of how a fungicide interrupts the disease cycle can be used to maximize an integrated pest control program by applying control products when the pathogen is most vulnerable. Leaf disks were excised from mature "Orbit White" geraniums treated with Endorse 2.5WP (polyoxin D zinc salt, biopesticide), chlorothalonil (B2 carcinogenic standard protectant), Bacillus subtilis (biocontrol agent) and boscalid (a new chemistry fungicide), and an untreated control. Disks were incubated under saturation conditions at 16DGC for 3, 6, 12, 24, 36 hours, then mounted, stained, and examined microscopically. Fungicide treatments reduced germination of spores and prevented elongation of germ tubes and formation of appressoria. As a result of this research, a better understanding of the mechanism of action of the
biopesticides/biocontrols and standard fungicides will be achieved. This information will establish a foundation for use in making control selections for managing Botrytis. New agents identified as management tools for control of Botrytis foliar blight. Four replicated trials evaluated 15 products, including an experimental product, reduced risk fungicides and biopesticides, for control of Botrytis blight on geranium. Development of resistance in B. cinerea to certain classes of fungicides has been documented, and can complicate choosing an effective control strategy. Plants were treated with fungicides after being inoculated with a spore-water mixture, dried, bagged, and shaded. Leaf infection and disease severity was significantly reduced compared to the untreated controls by applications of registered (Heritage 50WG, reduced risk; Daconil Weather Stik 6SC, B2 carcinogen) and unregistered products (Omega 500F, reduced risk; Endorse 2.5WP, biopesticide; Captan 80WDG, B2
carcinogen; BAS 510 70WG). Adding new diseases and new crops to labels will give growers products that can be used in a rotational program when fungicide resistance is a concern, and alternatives to fungicides that are B2 carcinogens. New agents identified as management tools for control of Phytophthora crown and root rot diseases. Four replicated trials evaluated 15 products, including three biopesticides and four reduced risk fungicides, for control of Phytophthora disease on poinsettia and snapdragon. Development of resistance in Phytophthora to mefenoxam fungicides has been documented, and can complicate choosing an effective control strategy. Plants were treated with fungicides, inoculated with Phytophthora, and evaluated for health and plant death. Products that significantly reduced Phytophthora disease compared with the inoculated controls included reduced risk fungicides (BAS 500 20EG, Cyazofamid 400SC, Fenamidone 500SC), biopesticides (Alude 2L, Biophos, Phostrol 6.69SC)
and other products (Aliette WDG, Captan 80WDG, Polyram 80DF, Stature DM 50WP, Terrazole 35WP). Adding new diseases and new crops to labels will give growers products that can be used in a rotational program when fungicide resistance is a concern, and alternatives to fungicides that are B2 carcinogens. 4c List any significant activities that support special target populations. Many greenhouse and nursery operations classify as small farms (< $250, 000 annual gross receipts), and a number of the findings reported here have been communicated directly to farmers or incorporated into specific crop management recommendations that will benefit from this and all grower groups. 5. Describe the major accomplishments over the life of the project, including their predicted or actual impact. Plant Disease Research Greenhouse and nursery crop producers maintain extraordinarily diverse cropping systems. Pathogen host range is a factor of great importance in understanding disease development.
Extensive greenhouse surveys at 11 U. S. facilities revealed that Phytophthora nicotianae was responsible for epidemics on fuchsia, snapdragon, million bells (calibrachoa), vinca, poinsettia, bacopa, verbena, African violet and dusty miller, whereas P. drechsleri reached epidemic levels only on poinsettia. Actual impact: Such information increases the capacity of plant pathologists to develop integrated management strategies. This research was conducted entirely in collaboration with grower cooperators who were experiencing large- scale epidemics from Phytophthora crown and root rot. [Milestone 1a; NP 303, Components I & IV]. Floriculture growers rely on fungicides as an important component of their disease management programs, and fungi that develop resistance to commonly used fungicides can complicate disease management. Over the course of this project we have screened 512 isolates of P. nicotianae and P. drechsleri from crops listed in the previous paragraph for sensitivity to
the commonly used fungicide mefenoxam. Of these 512 Phytophthora isolates, 375 (73.2%) were sensitive, 43 (8.4%) were intermediately sensitive and 94 (18.4%) were found to be fully insensitive to a dosage of mefenoxam. Actual impact: This indicates that the spread of mefenoxam- insensitive Phytophthora isolates may significantly reduce the efficacy of this fungicide. Continued use of mefenoxam when Phytophthora has developed resistance is costly and ineffective. As a result of this research, growers are now aware that any Phytophthora spp. should be screened for fungicide sensitivity. Further, the development of resistance indicates the need for new oomycete fungicides and/or biocontrols. [Milestone 1a; NP 303, Component IV] Growers of floral crops need more than fungicides to manage pathogens, and exploitation of weak links in a pathogen's life cycle may contribute to disease control. Sexual reproduction of P. drechsleri and P. nicotianae requires both the A1 and A2 mating
types and results in formation of oospores. Oospores have thick walls and can be long-lived and resistant to many disease-control measures, and as these spores contain genetic material from both parents, they may give rise to pathogen strains that are more aggressive than either parent. Surveys of 11 production facilities in the U.S. revealed that Phytophthora populations at each location were comprised of a single mating type. The absence of oospores in all production facilities sampled suggests that once disease is detected, strict and rigorous sanitation measures (e.g., removal and/or disposal of all infected and healthy plant material in conjunction with disinfestation of irrigation tanks, and growing equipment) may be effective in halting epidemics. [Milestone 1a; NP 303, Component IV] Understanding the genetics of plant pathogen populations is crucial to development of effective management techniques, yet, populations of Phytophthora infecting floral and nursery crops had not
been extensively characterized in these terms. Studies were conducted at 11 separate locations in the U.S. and all isolates recovered at each location had identical genetic fingerprints), indicating that the population structures within production facilities were clonal. Potential impact: These findings suggest that genetic diversity of Phytophthora is limited and that one or a few strains introduced into a greenhouse in even a small amount of diseased plant material can spread rapidly and cause great damage. This has important implications with respect to Phytophthora disease management. [Milestone 1a; NP 303, Component IV] Knowledge of how Phytophthora disease spreads and persists is crucial for effective disease management. Strains of P. nicotianae recovered from snapdragons at two field production sites in the southeastern U.S. were identical clones. These sites were receiving seedlings from the same source, and this clone persisted at one site from 2000 to 2001. Another
clone was recovered from verbena at three separate greenhouse facilities where one facility was supplying verbena to the other two. The results of this project showed growers the importance of purchasing clean starting material. Additional studies revealed that use of flood floors for irrigation entails the risk of furthering disease spread. Actual impact: Asexual reproduction plays an important role in epidemics and spread may occur between distant facilities via movement of plants. Growers must devise robust plans for avoiding the introduction of Phytophthora into their facilities and realize the need for absolute sanitization if eradication of an epidemic is to be effective. As a result of this research, at least one major grower has altered their irrigation methods and no longer uses flood floors. [Milestones 1a, d; NP 303, Components I, III & IV] Scab is a devastating disease of poinsettias that is a fairly new problem for growers and researchers in the U.S. New methodologies
were needed to allow research on poinsettia scab. Culture media and inoculation techniques were developed and successfully tested to allow isolation, growth, and sporulation of S. poinsettia and inoculation of poinsettia plants. These techniques are important to allow observation of the infection process on poinsettia. Potential impact: These techniques are important to other researchers interested in working with this unique pathogen. [Milestones 1c, d; NP 303, Components III & IV] Knowledge of environmental conditions that favor scab development may help growers avoid epidemics by manipulating their greenhouse environment. Spores of Sphaceloma poinsettiae were sampled from the atmosphere of a greenhouse with inoculated poinsettias. "Freedom Red" poinsettias were inoculated with Sphaceloma and placed in a humidity chamber (plastic over a PVC frame) in a greenhouse that was equipped with bench sprinklers that ran 4 times daily for 4-5 minutes and humidifiers that ran for 30
seconds every 10 minutes. Environmental monitoring equipment (recorded temperature, relative humidity and leaf wetness) and a Burkard volumetric spore sampler were placed in the chamber for 5 weeks. Sporulation of pigmented "Fawcetti" spores was visually observed on plants when the relative humidity was high, and "Fawcetti" spores were microscopically observed on some of slides of the air samples obtained through the Burkard spore trap. Actual impact: This research verifies the method of spore dispersal highlighting cultural strategies (i.e., drip irrigation) that could be used to limit spread and reduce disease. This is especially important for stock plant production. [Milestones 1c, d; NP 303, Components III & IV] Growing disease-resistant cultivars can supplement other disease management approaches for growers and reduce fungicide use. Eighty-nine poinsettia cultivars were evaluated for resistance to scab, and all varieties developed lesions and were unmarketable. Thirty-two
poinsettia cultivars were evaluated for resistance to P. nicotianae and P. drechsleri. Disease caused by P. drechsleri was especially severe, causing 100% death in 20 cultivars, while P. nicotianae caused up to 50% death in 9 cultivars. Although there were some differences in susceptibility among cultivars to Phytophthora disease, none were completely resistant. Actual impact: Growers need an integrated program which does not rely on a single tool for management of Phytophthora and Sphaceloma diseases. This research indicates that, currently, genetic resistance is not available to breeders, so growers must use cultural and fungicide methods to limit these disease problems. [Milestone 1d; NP 303, Component IV] Growers of floral crops need effective fungicides to use in their disease management programs. Eight-one products, including 17 biopesticides, 16 reduced risk fungicides, and a plant activator have been tested in 38 efficacy trials over the life of this project. Reduced
risk and new chemistry fungicides have been identified as effective alternatives to standard products for management of Phytophthora, Botrytis and Sphaceloma diseases. Potential Impact: Registration of and adding new crops to labels of effective reduced risk and new chemistry fungicides and biopesticides would give growers alternatives and/or rotational products to use with industry standards that are B2 carcinogens. This is especially important if the strains of fungi they are trying to manage have developed resistance to the standard fungicides. [Milestone 1e; NP 303; Components II & III] Floral crops are considered minor crops when it comes to registered pesticides. The IR-4 Project has worked with growers, scientists and commodity organizations since 1964 to identify minor crop pest control needs. The ornamentals program, added in 1977, has over 10,600 pesticide clearances to its credit. Since 2001, IR-4's petitions have comprised 50% of the total number approved by EPA. The
results of 7 trials testing various rates of 23 products for control of Botrytis and Phytophthora diseases have been reported to IR-4. Potential impact: Reporting results of fungicide trials to IR-4 can speed the addition of new diseases and new crops to labels of products, giving growers more choices for a fungicide program. Without these data, registrations for new products cannot be made. [Milestone 1e; NP 303; Components II & III] Mammalian Herbivore Research (Deer and Rodent Repellents) During FY2002 through FY2003, this project supported research on development of herbivore repellents. Funding for this research was discontinued at the end of FY2003. In studies conducted by S. Ries, R. Baughan, R. Schutzki and R. Beaudry of Michigan State University, volatile compounds were collected from repellent and non-repellent plants using SPME (Solid Phase microextraction) fibers in a closed system. More than 14 plant species were examined over the duration of the herbivore-repellent
project, and 24 chemicals, including some promising aromatic oils not currently used in commercial deer and rodent repellents were isolated and identified. A number of these chemicals and combinations of chemicals were formulated and tested in the field. Initial tests indicated potential for use of these materials in developing new more effective and longer-lasting repellents. [Milestones 2a, b, c; NP 304, Component V]. 6. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end- user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? Floriculture producers have been presented with information that will allow them to recognize and manage diseases on floral crops. Presentations included pictures of disease symptoms on various ornamental crops. Knowledge about the pathogens deemed helpful for disease management was
transferred, such as how the fungi produce spores, how the environment affects the disease cycle and how the disease is spread. Growers were informed of the results of fungicide efficacy tests comparing new agents, such as reduced risk fungicides and biopesticides, with industry standards. Integrated production strategies based upon this research were presented that included recommendations for environmental manipulation, scouting for the presence of disease, and fungicide recommendations including details on product choices such as mode of action (systemic versus protectant), rotation to avoid fungicide resistance in the pathogen, and effective application intervals. This technology was transferred to 100 growers at the meeting of the Society of American Florists in Orlando, FL in February of 2005, 150 growers at the ProGreen Expo in Denver, CO in January of 2005, 100 growers at the annual meeting of the Metropolitan Detroit Flower Growers' Association in Rockwood, MI in January
2005, and 75 growers at the Michigan Greenhouse Growers Expo in Lansing, MI in November 2004. 7. List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below). Publications in the Popular Press Hausbeck, M.K. Don't let your poinsettias become scabby. GM Pro. 2005. v. 25. p. 72-73. Hausbeck, M. Managing Botrytis on ornamental crops. Michigan State University Greenhouse Alert Newsletters. 2002. v. 11. Available from http://www.ipm.msu.edu/grnhouse02/G05-11-02.htm#2. Hausbeck, M. Managing diseases on geraniums. Michigan State University Greenhouse Alert Newsletters. 2002. v. 9. Available from http://www. ipm.msu.edu/grnhouse02/G04-9-02.htm. Presentations to Growers Hausbeck, M.K. Does Botrytis have you feeling too warm and fuzzy? Society of American Florists 21st Conference on Pest Management on Ornamentals, Orlando, FL. February, 2005. Hausbeck, M.K.
Managing Botrytis and powdery mildew. ProGreen Expo, Denver, CO. January, 2005. Hausbeck, M.K. Managing the water molds. ProGreen Expo, Denver, CO. January, 2005. Hausbeck, M.K. Management of foliar and soilborne diseases of ornamental crops. Metropolitan Detroit Flower Growers' Association Annual Meeting, Rockwood, MI, January, 2005. Hausbeck, M.K. Powdery and downy mildews. Mildews and Mites Session, Michigan Greenhouse Growers Expo, Lansing. November, 2004. Scientific Publications of Collaborators Hausbeck, M.K., Harlan, B.R., Woodworth, J.A. Evaluation of curative and preventive treatments for the control of Botrytis blight on geranium, 2004. Fungicide and Nematicide Tests. 2005. v. 60. p. OT005. Available at http://www.apsnet.org/online/FNtests/vol60/. Hausbeck, M.K., Woodworth, J.A., Harlan, B.R. Evaluations of registered and unregistered fungicides for the control of Phytophthora root rot of snapdragon, 2004. Fungicide and Nematicide Tests. 2005. v. 60. p. OT006.
Available at http://www.apsnet.org/online/FNtests/vol60/. Hausbeck, M.K., Woodworth, J.A., Linderman, S.D. Evaluation of 54 poinsettia cultivars for resistance to scab, 2004. Biological and Cultural Tests. 2005. v. 20. p. O013. Available at http://www.apsnet. org/online/BCTests/Vol20/. Hausbeck, M.K., Woodworth, J.A., Linderman, S.D. Evaluation of 57 poinsettia cultivars for resistance to scab, 2003. Biological and Cultural Tests. 2005. v. 20. p. O014. Available at http://www.apsnet. org/online/BCTests/Vol20/. Webster, B.J., Hausbeck, M.K. Evaluation of reduced risk fungicides and biopesticides for control of Botrytis blight of geranium, 2004. Fungicide and Nematicide Tests. 2005. v. 60. p. OT009. Available at http://www.apsnet.org/online/FNtests/vol60/.
Impacts
(N/A)
Publications
- Hausbeck, M.K., Linderman, S. D. Evaluation of fungicides in managing Botrytis blight of geranium, 2000. Fungicide and Nematicide Tests. 2002. v. 57. p. OT11.
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Progress 09/20/00 to 09/19/05
Outputs
Progress Report 1. What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? Why does it matter? Greenhouse-grown floricultural crops are constantly being threatened by the plant pathogenic fungus Botrytis cinerea, which causes gray mold or Botrytis blight. The wet, humid greenhouse environment favors rapid growth and prolific sporulation of B. cinerea. Many important floricultural crops are susceptible to Botrytis, with certain plants and plant parts being highly susceptible and the age of the plants also playing a factor in infection. Thus, Botrytis infection can occur as leaf spots; blighting; stem cankers; rots of corms, rhizomes, tubers and seeds; and pre- or postemergence damping off. Botrytis blight continues to cause significant losses at all stages of floriculture production, including seed, plug, bedding plant or potted plant production, stock plant and cuttings
production, and storage and/or shipment of cuttings and cut flowers. Botrytis conidia can be released into the greenhouse atmosphere during any grower activity which disturbs the plants, including irrigating, spraying pesticides, and harvesting cuttings. Natural conidia release occurs approximately midmorning and midafternoon and coincides with a rapid decrease in relative humidity. A conidium may survive for at least three weeks before germination, and may potentially be shipped from greenhouse to greenhouse. Failure to control Botrytis at one production stage in any crop can have negative ramifications for subsequent stages and other susceptible crops in the same facility. Development of resistance in B. cinerea to certain classes of fungicides can complicate choosing an effective control strategy. Phytophthora crown and root rot of ornamentals is caused by Phytophthora spp., a fungal-like organism that produces sporangia which releases swimming spores upon immersion in water.
Sporangia likely play a major role in epidemics, spreading disease from initial points of infection. The seriousness of the problem due to Phytophthora infection varies according to production facility. We have characterized Phytophthora epidemics, and the damages ranged from relatively minor (infection confined to limited foci) to quite serious (50-60% of the grower's production lost to Phytophthora, with a value in excess of $200,000). A better understanding of which Phytophthora spp. are causing problems and how the populations are distributed in space and time provides useful information for developing management strategies. There have been cases of Phytophthora spp. developing resistance to metalaxyl/mefenoxam fungicides. Poinsettias continue to account for the largest value of wholesale potted flowering plant sales for the state of Michigan and the U.S., and the national value of the crop has been steadily increasing. Poinsettia scab (causal agent, Sphaceloma poinsettiae) is
a fungal disease that is spread by water, and since its discovery in the early 1940s in Florida and Hawaii, it has become the limiting factor in the outdoor production of poinsettias in tropical areas of the U.S. The pathogen causes lesions on the stems, leaves and petioles of poinsettias, rendering the plants unmarketable. In severe cases, defoliation, girdling or elongation of stems may occur. Virtually no research has been conducted on the epidemiology of this fungus due to the fact that scab has been managed successfully in the past by use of clean stock plant materials. The recent shift in poinsettia stock plant production to Central America, where the pathogen is indigenous, has resulted in outbreaks of scab in U. S. greenhouses. Growers in the U.S. need management strategies for this new disease of poinsettias to produce a quality crop for consumers. 2. List by year the currently approved milestones (indicators of research progress) 1) Plant Disease Research a. Identify
the major Phytophthora spp. affecting floriculture production and determine which aspects of Phytophthora's life history contribute significantly to control failure. b. Determine the role of environment in the disease cycle of B. cinerea and investigate environmental manipulation as a viable management tool for flower and leaf blight. c. Determine the role of the environment in the disease cycle of S. poinsettiae. d. Develop durable production strategies for preventing and eliminating disease caused by Phytophthora spp., B. cinerea, and S. poinsettiae on floriculture hosts. e. Screen novel agents for their potential as management tools for control of Phytophthora crown and root rot disease, Botrytis flower and leaf blight, and poinsettia scab. 2) Mammalian Herbivore Research (FY 2002-FY 2003) a. Isolate and identify natural compounds from browse-resistant plant species, and bioassay these compounds for deer and rabbit repellency. b. Evaluate most promising repellents for
phytotoxicity. c. Develop efficacious repellent formulations that resist breakdown by the environment and/or release active ingredients slowly to provide practical, long-lasting plant protection. 4a List the single most significant research accomplishment during FY 2006. New biopesticide found effective as a management tool for control of Botrytis foliar blight. We have been testing Endorse 2.5WP since 2002 for efficacy against Botrytis blight. This biopesticide (active ingredient, polyoxin D zinc salt) again proved especially effective against this disease in our FY 2005 trials. Fungicides are an important component of disease control for growers. Identifying alternatives to B2 carcinogenic fungicides reduces potential harm to growers, consumers and the environment. Using these new products in rotation with others reduces the potential development of fungicide resistance in B. cinerea. 4b List other significant research accomplishment(s), if any. Phytophthora spp. affecting
floriculture production characterized. Prompt identification and characterization of the Phytophthora spp. infecting growers' crops is needed to maximize disease control programs. To accomplish this, monitoring and processing of diseased samples from growers has continued throughout this project. In particular, we have partnered with Diagnostic Services on the campus of Michigan State University to provide screening for fungicide sensitivity of pathogen samples submitted by growers. As a result of this testing, growers received full information regarding the most effective means of disease control. Poinsettia leaf clearing technique developed. A clearing technique was developed for poinsettia leaf tissue. Leaf tissue must be transparent (cleared of all pigment) for fungal spores to be observed microscopically. A new leaf clearing technique was needed because the latex in poinsettia complicates the clearing process, and chloral hydrate, a chemical used in previously published
techniques, is a controlled substance that requires a permit for use. Research found that immersion in a 1:1 solution of 95% ethanol and 1M potassium hydroxide at room temperature for two hours or immersion in a heated solution for 2 seconds successfully cleared poinsettia leaf tissue of chlorophyll and latex. Using this technique on inoculated poinsettia leaves after varying a) the time leaves remain wet and b) the temperature during the wetness period allows determination of minimum leaf wetness duration and optimum temperature for successful infection of poinsettia by S. poinsettiae. Mechanism of spread of poinsettia scab pathogen identified. Effects of relative humidity versus water splash on the scab disease cycle were investigated in a humidity chamber in a greenhouse. It was determined that high relative humidity alone was not enough to prompt spore dispersal of S. poinsettiae from diseased to uninoculated plants; however, splashing water, as occurs during routine watering
of plants, did disperse spores and caused new infection sites to arise on uninoculated poinsettias. These findings have an impact on cultural recommendations for poinsettias. Overhead watering could exacerbate epidemics of scab, whereas drip irrigation would minimize spore dispersal of Sphaceloma. Environmental effects on host infection and colonization by Botrytis cinerea determined. Knowledge of the infection process can allow growers to manipulate the greenhouse environment to manage disease by targeting the pathogen at a vulnerable stage. Geranium leaf disks were inoculated with B. cineria spores and incubated under saturation conditions in moist chambers at varying temperatures and lengths of time and then examined microscopically. Optimum temperature for Botrytis growth was determined to be 16 degrees C. At this temperature, few conidia germinated within 3 hours, most germinated within 6 hours, and time periods greater than 6 hours supported elongation of germ tubes and
formation of infection structures (appressoria). Based on this research, it is recommended that growers keep susceptible plants as dry as possible. If plants remain wet for more than 6 hours, growers should apply a systemic rather than a protectant fungicide for Botrytis management. Effects of fungicides with differing modes of action on the Botrytis infection process determined. Knowledge of how a fungicide interrupts the disease cycle can be used to maximize an integrated pest control program by applying control products when the pathogen is most vulnerable. Leaf disks were excised from mature 'Orbit White' geraniums treated with Endorse 2.5WP (polyoxin D zinc salt, biopesticide), chlorothalonil (B2 carcinogenic standard protectant), Bacillus subtilis (biocontrol agent) and boscalid (a new chemistry fungicide), and an untreated control. Disks were incubated under saturation conditions at 16 degrees C for 3, 6, 12, 24, 36 hours, then mounted, stained, and examined microscopically.
Fungicide treatments reduced germination of spores and prevented elongation of germ tubes and formation of appressoria. As a result of this research, a better understanding of the mechanism of action of the biopesticides/biocontrols and standard fungicides will be achieved. This information will establish a foundation for use in making control selections for managing Botrytis. New agents identified as management tools for control of Botrytis foliar blight. Four replicated trials evaluated 15 products, including an experimental product, reduced risk fungicides and biopesticides, for control of Botrytis blight on geranium. Development of resistance in B. cinerea to certain classes of fungicides has been documented, and can complicate choosing an effective control strategy. Plants were treated with fungicides after being inoculated with a spore-water mixture, dried, bagged, and shaded. Leaf infection and disease severity was significantly reduced compared to the untreated controls
by applications of registered (Heritage 50WG, reduced risk; Daconil Weather Stik 6SC, B2 carcinogen) and unregistered products (Omega 500F, reduced risk; Endorse 2.5WP, biopesticide; Captan 80WDG, B2 carcinogen; BAS 510 70WG). Adding new diseases and new crops to labels will give growers products that can be used in a rotational program when fungicide resistance is a concern, and alternatives to fungicides that are B2 carcinogens. New agents identified as management tools for control of Phytophthora crown and root rot diseases. Four replicated trials evaluated 15 products, including three biopesticides and four reduced risk fungicides, for control of Phytophthora disease on poinsettia and snapdragon. Development of resistance in Phytophthora to mefenoxam fungicides has been documented, and can complicate choosing an effective control strategy. Plants were treated with fungicides, inoculated with Phytophthora, and evaluated for health and plant death. Products that significantly
reduced Phytophthora disease compared with the inoculated controls included reduced risk fungicides (BAS 500 20EG, Cyazofamid 400SC, Fenamidone 500SC), biopesticides (Alude 2L, Biophos, Phostrol 6.69SC) and other products (Aliette WDG, Captan 80WDG, Polyram 80DF, Stature DM 50WP, Terrazole 35WP). Adding new diseases and new crops to labels will give growers products that can be used in a rotational program when fungicide resistance is a concern, and alternatives to fungicides that are B2 carcinogens. 4c List significant activities that support special target populations. Many greenhouse and nursery operations classify as small farms (< $250, 000 annual gross receipts), and a number of the findings reported here have been communicated directly to farmers or incorporated into specific crop management recommendations that will benefit from this and all grower groups. 5. Describe the major accomplishments to date and their predicted or actual impact. The plant disease research
accomplishments reported below relate to National Program (NP) 303 (Plant Diseases) and represent contributions to research components I (Identification and Classification of Pathogens), II (Biological Control), III (Cultural Control) and IV (Pathogen Biology, Genetics, Population Dynamics, Spread, and Relationships with Hosts and Vectors). The mammalian herbivore research accomplishments relate to National Program 304 (Crop Protection and Quarantine), component V (Pest Control Technologies). Plant Disease Research Greenhouse and nursery crop producers maintain extraordinarily diverse cropping systems. Pathogen host range is a factor of great importance in understanding disease development. Extensive greenhouse surveys at 11 U. S. facilities revealed that Phytophthora nicotianae was responsible for epidemics on fuchsia, snapdragon, million bells (calibrachoa), vinca, poinsettia, bacopa, verbena, African violet and dusty miller, whereas P. drechsleri reached epidemic levels only on
poinsettia. Actual impact: Such information increases the capacity of plant pathologists to develop integrated management strategies. This research was conducted entirely in collaboration with grower cooperators who were experiencing large- scale epidemics from Phytophthora crown and root rot. [Milestone 1a; NP 303, Components I & IV]. Floriculture growers rely on fungicides as an important component of their disease management programs, and fungi that develop resistance to commonly used fungicides can complicate disease management. Over the course of this project we have screened 512 isolates of P. nicotianae and P. drechsleri from crops listed in the previous paragraph for sensitivity to the commonly used fungicide mefenoxam. Of these 512 Phytophthora isolates, 375 (73.2%) were sensitive, 43 (8.4%) were intermediately sensitive and 94 (18.4%) were found to be fully insensitive to a dosage of mefenoxam. Actual impact: This indicates that the spread of mefenoxam- insensitive
Phytophthora isolates may significantly reduce the efficacy of this fungicide. Continued use of mefenoxam when Phytophthora has developed resistance is costly and ineffective. As a result of this research, growers are now aware that any Phytophthora spp. should be screened for fungicide sensitivity. Further, the development of resistance indicates the need for new oomycete fungicides and/or biocontrols. [Milestone 1a; NP 303, Component IV] Growers of floral crops need more than fungicides to manage pathogens, and exploitation of weak links in a pathogen's life cycle may contribute to disease control. Sexual reproduction of P. drechsleri and P. nicotianae requires both the A1 and A2 mating types and results in formation of oospores. Oospores have thick walls and can be long-lived and resistant to many disease-control measures, and as these spores contain genetic material from both parents, they may give rise to pathogen strains that are more aggressive than either parent. Surveys
of 11 production facilities in the U.S. revealed that Phytophthora populations at each location were comprised of a single mating type. The absence of oospores in all production facilities sampled suggests that once disease is detected, strict and rigorous sanitation measures (e.g., removal and/or disposal of all infected and healthy plant material in conjunction with disinfestation of irrigation tanks, and growing equipment) may be effective in halting epidemics. [Milestone 1a; NP 303, Component IV] Understanding the genetics of plant pathogen populations is crucial to development of effective management techniques, yet, populations of Phytophthora infecting floral and nursery crops had not been extensively characterized in these terms. Studies were conducted at 11 separate locations in the U.S. and all isolates recovered at each location had identical genetic fingerprints), indicating that the population structures within production facilities were clonal. Potential impact: These
findings suggest that genetic diversity of Phytophthora is limited and that one or a few strains introduced into a greenhouse in even a small amount of diseased plant material can spread rapidly and cause great damage. This has important implications with respect to Phytophthora disease management. [Milestone 1a; NP 303, Component IV] Knowledge of how Phytophthora disease spreads and persists is crucial for effective disease management. Strains of P. nicotianae recovered from snapdragons at two field production sites in the southeastern U.S. were identical clones. These sites were receiving seedlings from the same source, and this clone persisted at one site from 2000 to 2001. Another clone was recovered from verbena at three separate greenhouse facilities where one facility was supplying verbena to the other two. The results of this project showed growers the importance of purchasing clean starting material. Additional studies revealed that use of flood floors for irrigation
entails the risk of furthering disease spread. Actual impact: Asexual reproduction plays an important role in epidemics and spread may occur between distant facilities via movement of plants. Growers must devise robust plans for avoiding the introduction of Phytophthora into their facilities and realize the need for absolute sanitization if eradication of an epidemic is to be effective. As a result of this research, at least one major grower has altered their irrigation methods and no longer uses flood floors. [Milestones 1a, d; NP 303, Components I, III & IV] Scab is a devastating disease of poinsettias that is a fairly new problem for growers and researchers in the U.S. New methodologies were needed to allow research on poinsettia scab. Culture media and inoculation techniques were developed and successfully tested to allow isolation, growth, and sporulation of S. poinsettia and inoculation of poinsettia plants. These techniques are important to allow observation of the
infection process on poinsettia. Potential impact: These techniques are important to other researchers interested in working with this unique pathogen. [Milestones 1c, d; NP 303, Components III & IV] Knowledge of environmental conditions that favor scab development may help growers avoid epidemics by manipulating their greenhouse environment. Spores of Sphaceloma poinsettiae were sampled from the atmosphere of a greenhouse with inoculated poinsettias. 'Freedom Red' poinsettias were inoculated with Sphaceloma and placed in a humidity chamber (plastic over a PVC frame) in a greenhouse that was equipped with bench sprinklers that ran 4 times daily for 4-5 minutes and humidifiers that ran for 30 seconds every 10 minutes. Environmental monitoring equipment (recorded temperature, relative humidity and leaf wetness) and a Burkard volumetric spore sampler were placed in the chamber for 5 weeks. Sporulation of pigmented "Fawcetti" spores was visually observed on plants when the relative
humidity was high, and "Fawcetti" spores were microscopically observed on some of slides of the air samples obtained through the Burkard spore trap. Actual impact: This research verifies the method of spore dispersal highlighting cultural strategies (i.e., drip irrigation) that could be used to limit spread and reduce disease. This is especially important for stock plant production. [Milestones 1c, d; NP 303, Components III & IV] Growing disease-resistant cultivars can supplement other disease management approaches for growers and reduce fungicide use. Eighty-nine poinsettia cultivars were evaluated for resistance to scab, and all varieties developed lesions and were unmarketable. Thirty-two poinsettia cultivars were evaluated for resistance to P. nicotianae and P. drechsleri. Disease caused by P. drechsleri was especially severe, causing 100% death in 20 cultivars, while P. nicotianae caused up to 50% death in 9 cultivars. Although there were some differences in susceptibility
among cultivars to Phytophthora disease, none were completely resistant. Actual impact: Growers need an integrated program which does not rely on a single tool for management of Phytophthora and Sphaceloma diseases. This research indicates that, currently, genetic resistance is not available to breeders, so growers must use cultural and fungicide methods to limit these disease problems. [Milestone 1d; NP 303, Component IV] Growers of floral crops need effective fungicides to use in their disease management programs. Eight-one products, including 17 biopesticides, 16 reduced risk fungicides, and a plant activator have been tested in 38 efficacy trials over the life of this project. Reduced risk and new chemistry fungicides have been identified as effective alternatives to standard products for management of Phytophthora, Botrytis and Sphaceloma diseases. Potential Impact: Registration of and adding new crops to labels of effective reduced risk and new chemistry fungicides and
biopesticides would give growers alternatives and/or rotational products to use with industry standards that are B2 carcinogens. This is especially important if the strains of fungi they are trying to manage have developed resistance to the standard fungicides. [Milestone 1e; NP 303; Components II & III] Floral crops are considered minor crops when it comes to registered pesticides. The IR-4 Project has worked with growers, scientists and commodity organizations since 1964 to identify minor crop pest control needs. The ornamentals program, added in 1977, has over 10,600 pesticide clearances to its credit. Since 2001, IR-4's petitions have comprised 50% of the total number approved by EPA. The results of 7 trials testing various rates of 23 products for control of Botrytis and Phytophthora diseases have been reported to IR-4. Potential impact: Reporting results of fungicide trials to IR-4 can speed the addition of new diseases and new crops to labels of products, giving growers
more choices for a fungicide program. Without these data, registrations for new products cannot be made. [Milestone 1e; NP 303; Components II & III] Mammalian Herbivore Research (Deer and Rodent Repellents) During FY2002 through FY2003, this project supported research on development of herbivore repellents. Funding for this research was discontinued at the end of FY2003. In studies conducted by S. Ries, R. Baughan, R. Schutzki and R. Beaudry of Michigan State University, volatile compounds were collected from repellent and non-repellent plants using SPME (Solid Phase microextraction) fibers in a closed system. More than 14 plant species were examined over the duration of the herbivore-repellent project, and 24 chemicals, including some promising aromatic oils not currently used in commercial deer and rodent repellents were isolated and identified. A number of these chemicals and combinations of chemicals were formulated and tested in the field. Initial tests indicated potential
for use of these materials in developing new more effective and longer-lasting repellents. [Milestones 2a, b, c; NP 304, Component V]. 6. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end- user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? Floriculture producers have been presented with information that will allow them to recognize and manage diseases on floral crops. Presentations included pictures of disease symptoms on various ornamental crops. Knowledge about the pathogens deemed helpful for disease management was transferred, such as how the fungi produce spores, how the environment affects the disease cycle and how the disease is spread. Growers were informed of the results of fungicide efficacy tests comparing new agents, such as reduced risk fungicides and biopesticides, with industry standards.
Integrated production strategies based upon this research were presented that included recommendations for environmental manipulation, scouting for the presence of disease, and fungicide recommendations including details on product choices such as mode of action (systemic versus protectant), rotation to avoid fungicide resistance in the pathogen, and effective application intervals. This technology was transferred to 100 growers at the meeting of the Society of American Florists in Orlando, FL in February of 2005, 150 growers at the ProGreen Expo in Denver, CO in January of 2005, 100 growers at the annual meeting of the Metropolitan Detroit Flower Growers' Association in Rockwood, MI in January 2005, and 75 growers at the Michigan Greenhouse Growers Expo in Lansing, MI in November 2004. 7. List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below). Publications
in the Popular Press: Hausbeck, M.K. Don't let your poinsettias become scabby. GM Pro. 2005. v. 25. p. 72-73. Hausbeck, M. Managing Botrytis on ornamental crops. Michigan State University Greenhouse Alert Newsletters. 2002. v. 11. Available http://www.ipm.msu.edu/grnhouse02/G05-11-02.htm#2. Hausbeck, M. Managing diseases on geraniums. Michigan State University Greenhouse Alert Newsletters. 2002. v. 9. Available http://www.ipm.msu. edu/grnhouse02/G04-9-02.htm. Presentations to Growers: Hausbeck, M.K. Does Botrytis have you feeling too warm and fuzzy? Society of American Florists 21st Conference on Pest Management on Ornamentals, Orlando, FL. February, 2005. Hausbeck, M.K. Managing Botrytis and powdery mildew. ProGreen Expo, Denver, CO. January, 2005. Hausbeck, M.K. Managing the water molds. ProGreen Expo, Denver, CO. January, 2005. Hausbeck, M.K. Management of foliar and soilborne diseases of ornamental crops. Metropolitan Detroit Flower Growers' Association Annual
Meeting, Rockwood, MI, January, 2005. Hausbeck, M.K. Powdery and downy mildews. Mildews and Mites Session, Michigan Greenhouse Growers Expo, Lansing. November, 2004. Scientific Publications of Collaborators: Hausbeck, M.K., Harlan, B.R., Woodworth, J.A. Evaluation of curative and preventive treatments for the control of Botrytis blight on geranium, 2004. Fungicide and Nematicide Tests. 2005. v. 60. p. OT005. Available http://www.apsnet.org/online/FNtests/vol60/. Hausbeck, M.K., Woodworth, J.A., Harlan, B.R. Evaluations of registered and unregistered fungicides for the control of Phytophthora root rot of snapdragon, 2004. Fungicide and Nematicide Tests. 2005. v. 60. p. OT006. Available http://www.apsnet.org/online/FNtests/vol60/. Hausbeck, M.K., Woodworth, J.A., Linderman, S.D. Evaluation of 54 poinsettia cultivars for resistance to scab, 2004. Biological and Cultural Tests. 2005. v. 20. p. O013. Available http://www.apsnet. org/online/BCTests/Vol20/. Hausbeck, M.K.,
Woodworth, J.A., Linderman, S.D. Evaluation of 57 poinsettia cultivars for resistance to scab, 2003. Biological and Cultural Tests. 2005. v. 20. p. 14. Available http://www.apsnet. org/online/BCTests/Vol20/. Webster, B.J., Hausbeck, M.K. Evaluation of reduced risk fungicides and biopesticides for control of Botrytis blight of geranium, 2004. Fungicide and Nematicide Tests. 2005. v. 60. p. OT009. Available http://www.apsnet. org/online/FNtests/vol60/.
Impacts
(N/A)
Publications
- Hausbeck, M.K., Linderman, S. D. Evaluation of fungicides in managing Botrytis blight of geranium, 2000. Fungicide and Nematicide Tests. 2002. v. 57. p. OT11.
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Progress 10/01/03 to 09/30/04
Outputs
1. What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? What does it matter? Greenhouse-grown floricultural crops are constantly being threatened by the plant pathogenic fungus Botrytis cinerea, which causes gray mold or Botrytis blight. The wet, humid greenhouse environment favors rapid growth and prolific sporulation of B. cinerea. Many important floricultural crops are susceptible to Botrytis, with certain plants and plant parts being highly susceptible, and the age of the plants also playing a factor in infection. Thus, Botrytis infection can occur as leaf spots; blighting; stem cankers; rots of corms, rhizomes, tubers and seeds; and pre- or postemergence damping off. Botrytis blight continues to cause significant losses at all stages of floriculture production, including seed, plug, bedding plant or potted plant production, stock plant and cuttings production, and
storage and/or shipment of cuttings and cut flowers. Botrytis conidia can be released into the greenhouse atmosphere during any grower activity which disturbs the plants, including irrigating, spraying pesticides, and harvesting cuttings. Natural conidia release occurs approximately midmorning and mid-afternoon and coincides with a rapid decrease in relative humidity. A conidium may survive for at least three weeks before germination, and may potentially be shipped from greenhouse to greenhouse. Failure to control Botrytis at one production stage in any crop can have negative ramifications for subsequent stages and other susceptible crops in the same facility. Development of resistance in B. cinerea to certain classes of fungicides can complicate choosing an effective control strategy. Phytophthora crown and root rot of ornamentals is caused by Phytophthora spp., fungi that produce sporangia which are able to release swimming spores upon immersion in water. Sporangia likely play a
major role in epidemics, spreading disease from initial points of infection. The seriousness of the problem due to Phytophthora infection varies according to production facility. We have characterized Phytophthora epidemics and the damages ranged from relatively minor (infection confined to limited foci) to quite serious (50-60% of the grower's production lost to Phytophthora with a value in excess of $200,000). A better understanding of which Phytophthora spp. are causing problems and how the populations are distributed in space and time provides useful information for developing management strategies. There have been cases of Phytophthora spp. developing resistance to metalaxyl/mefenoxam fungicides. Poinsettias continue to account for the largest value of wholesale potted flowering plant sales for the state of Michigan and the U.S., and the national value of the crop has been steadily increasing. Poinsettia scab, (causal agent, Sphaceloma poinsettiae), is a fungal disease that
is spread by water, and is the limiting factor in the outdoor production of poinsettias in tropical areas of the U.S. since its discovery in the early 1940s in Florida and Hawaii. The pathogen causes lesions on the stems, leaves and petioles of poinsettias, rendering the plants unmarketable. In severe cases, defoliation, girdling or elongation of stems may occur. Virtually no research has been conducted on the epidemiology of this fungus due to the fact that scab has been managed successfully in the past by use of clean stock plant materials. The recent shift in poinsettia stock plant production to Central America, where the pathogen is indigenous, has resulted in outbreaks of scab in U. S. greenhouses. Growers in the U.S. need management strategies for this new disease of poinsettias to produce a quality crop for consumers. 2. List the milestones (indicators of progress) from your Project Plan. 1) Plant Disease Research: a. Identify the major Phytophthora spp. affecting
floriculture production and determine which aspects of Phytophthora's life history contribute significantly to control failure. b. Determine the role of environment in the disease cycle of B. cinerea and investigate environmental manipulation as a viable management tool for flower and leaf blight. c. Determine the role of the environment in the disease cycle of S. poinsettiae. d. Develop durable production strategies for preventing and eliminating disease caused by Phytophthora spp., B. cinerea, and S. poinsettiae on floriculture hosts. e. Screen novel agents for their potential as management tools for control of Phytophthora crown and root rot disease, Botrytis flower and leaf blight, and poinsettia scab. 2) Mammalian Herbivore Research (FY2002'FY2003): a. Isolate and identify natural compounds from browse-resistant plant species, and bioassay these compounds for deer and rabbit repellency. b. Evaluate most promising repellents for phytotoxicity. c. Develop efficacious
repellent formulations that resist breakdown by the environment and/or release active ingredients slowly to provide practical, long-lasting plant protection. 3. Milestones: A. List the milestones (from the list in Question #2) that were scheduled to be addressed in FY 2004. How many milestones did you fully or substantially meet in FY 2004 and indicate which ones were not fully or substantially met, briefly explain why not, and your plans to do so. 1) a. Determine the role of environment in the disease cycle of B. cinerea and investigate environmental manipulation as a viable management tool for flower and leaf blight. - Quantify the influence of the environment (temperature, relative humidity, and duration of leaf wetness) on the infection, colonization, and reproductive processes of Botrytis. - Develop methodologies and determine the appropriate timing of environmental manipulation as a means of averting or interrupting a Botrytis disease epidemic. This milestone was not met
because a new graduate student is developing this portion of the project as a Master's thesis and required training. We plan to meet this milestone by December 2005. This graduate student has received the required training and has initiated the research project. 1) b. Determine the role of the environment in the disease cycle of S. poinsettiae. - Determine leaf wetness durations and temperatures which promote disease expression on poinsettia in growth chambers by observing symptoms after 14 days of (a) varying the temperatures (20, 25, 30, 35 C) with 24 hours of leaf wetness, and (b) varying leaf wetness duration at the most favorable temperature determined in (a). This milestone was not substantially met because of the initial difficulty in handling this pathogen. The necessary techniques have been developed to allow this project to move forward. We plan to meet this milestone by December 2005. - Determine the environmental parameters (temperature, humidity, light) which
influence the production of colored and hyaline conidia produced by inoculated tissue incubated in environmental chambers. This milestone was met, and is listed as the single most significant accomplishment of FY 2004. 1) c. Develop durable production strategies for preventing and eliminating disease caused by Phytophthora spp., B. cinerea, and S. poinsettiae on floriculture hosts. - Research results from 2003-04 will be presented at meetings and trade shows, and published results in refereed journals as appropriate. This milestone was fully met. 1) d. Screen novel agents for their potential as management tools for control of Phytophthora crown and root rot disease, Botrytis flower and leaf blight, and poinsettia scab. This milestone was fully met. 3B. List the milestones that you expect to address over the next 3 years (FY 2005, 2006, & 2007). What do you expect to accomplish, year by year, over the next 3 years under each milestone?: NOTE: Funding for this project ends after
FY 2005. New funding will be needed to continue research for FY 2006. 1) a. Identify the major Phytophthora spp. affecting floriculture production and determine which aspects of Phytophthora's life history contribute significantly to control failure. FY 2005-06: Isolate, identify and characterize Phytophthora spp. from diseased plants, including fungicide sensitivity. Investigate the occurrence of Phytophthora disease in floriculture production facilities. 1) b. Determine the role of environment in the disease cycle of B. cinerea and investigate environmental manipulation as a viable management tool for flower and leaf blight. FY 2005-06: Quantify the influence of the environment (temperature, relative humidity, and duration of leaf wetness) on the infection, colonization, and reproductive processes of Botrytis. 1) c. Determine the role of the environment in the disease cycle of S. poinsettiae. FY 2005-06: Determine minimum leaf wetness duration needed for infection by
observing symptoms 14 days after inoculation and varying: (a) the length of leaf wetness intervals by hourly increments at 25'C, (b) once the minimum time is determined, the temperatures (20, 25, 30, 35'C). FY 2005-06: Monitor the effects of the greenhouse environment on production of conidia of Sphaceloma by placing a Burkard volumetric spore sampler and a WatchDog data logger in a polyethylene hoop greenhouse with 300 'Freedom Red' poinsettias. Plants will be inoculated and the relative humidity raised by operating benchtop sprinklers 4 times daily for 4-5 minutes. Spores will be counted and compared with the environmental data. 1) d. Develop durable production strategies for preventing and eliminating disease caused by Phytophthora spp., B. cinerea, and S. poinsettiae on floriculture hosts. FY 2005-06: Research results will be integrated into disease management recommendations and presented at meetings and trade shows, and published results in refereed journals as appropriate.
1) e. Screen novel agents for their potential as management tools for control of Phytophthora crown and root rot disease, Botrytis flower and leaf blight, and poinsettia scab. FY 2005-06: Efficacy trials will continue to test unregistered products for disease control, with emphasis on reduced risk fungicides and biopesticides. 4. What were the most significant accomplishments this past year? A. Single Most Significant Accomplishment during FY 2004: Spores of Sphaceloma poinsettiae were sampled from the atmosphere of a greenhouse with inoculated poinsettias. Little is known about the factors that influence the development of scab disease on poinsettias. 'Freedom Red' poinsettias were inoculated with Sphaceloma and placed in a humidity chamber (plastic over a PVC frame) in a greenhouse that was equipped with bench sprinklers that ran 4 times daily for 4-5 minutes and humidifiers that ran for 30 seconds every 10 minutes. Environmental monitoring equipment (recorded temperature,
relative humidity and leaf wetness) and a Burkard volumetric spore sampler were placed in the chamber for 5 weeks. Sporulation of pigmented 'Fawcetti' spores was visually observed on plants when the relative humidity was high, and 'Fawcetti' spores were microscopically observed on some of slides of the air samples obtained through the Burkard spore trap. Knowledge of environmental conditions which favor scab development may help growers avoid scab epidemics by manipulating their greenhouse environment. B. Other significant accomplishment(s); if any: Two replicated trials testing the resistance of poinsettia cultivars to Sphaceloma disease (scab) were evaluated. Disease management programs that incorporate knowledge of cultivar susceptibility can reduce the number of fungicide sprays needed; using as few sprays as possible helps to delay the development of resistance in the pathogen and reduces growers' costs. One trial had 57 cultivars, the second trial had 54 cultivars (some were
repeats), for a total of 89 different poinsettia varieties from 5 suppliers. Plants were bagged for 48 hours post- inoculation, and data collected on disease severity and lesion number 14 days post-inoculation. All plants developed lesions on stems, petioles and leaves, and were unmarketable. As it seems there is no genetic resistance yet observed, this research indicates the importance of investigating other aspects of scab control, such as fungicide efficacy testing and gaining knowledge of the disease cycle. Three replicated trials evaluating 25 fungicides for the control of poinsettia scab were conducted. Some fungicides currently used by growers are at risk due both to development of resistance by the disease- causing organisms and to impending regulatory action by the Food Quality Protection Act. Fungicide treatments, including 5 biopesticides and 8 reduced risk products, were applied with a compressed air hand-pump sprayer and allowed to dry, Sphaceloma inoculum was
sprayed to runoff, poinsettias were bagged for 48 hours post-inoculation and evaluated for disease 14 days post-inoculation. Especially effective fungicides for scab management included Dithane DF (mancozeb, B2 carcinogen), Compass O 50WDG (trifloxystrobin, reduced risk), BAS 516 38WG (pyraclostrobin + boscalid, reduced risk); other promising products were Daconil Weather Stik 6F (chlorothalonil, B2 carcinogen), Heritage 50WG (azoxystrobin, reduced risk), BAS 500 20WG (pyraclostrobin, reduced risk), Switch 62.5 WG (cyprodinil + fludioxonil, reduced risk), Terraguard 50W (triflumizole) . Adding new diseases and new crops to labels will give growers products that can be used in a rotational program when fungicide resistance is a concern, and alternatives to fungicides that are B2 carcinogens. The results of 7 fungicides evaluated for the control of Botrytis, Phytophthora and Sphaceloma diseases were reported to IR-4 in FY2004. The IR-4 Project has worked with growers, scientists and
commodity organizations since 1964 to identify minor crop pest control needs with 10,600 ornamentals clearances to its credit, and since 2001, IR-4's petitions have comprised 50% of the total number approved by EPA. Three application rates of 710-145f (Bacillus licheniformis, biopesticide) were tested on Botrytis; 710-145f (Bacillus licheniformis, biopesticide), Ranman 3.3SC (cyazofamid, reduced risk), Reason 4.17SC (fenamidone, reduced risk), BAS 516 38WG (pyraclostrobin + boscalid, reduced risk), and Camelot 58EC (copper salts) were tested on Phytophthora; BAS 516 38WG (pyraclostrobin + boscalid, reduced risk), Heritage 50WG (azoxystrobin, reduced risk), Cuprofix Disperss 37DF (copper sulfate) and Camelot 58EC (copper salts) were tested on Sphaceloma for disease incidence and phytoxicity. Reporting results of fungicide trials to IR-4 can speed the addition of new diseases and new crops to labels of products, giving growers more choice for a fungicide program. Three replicated
trials evaluated 21 products, including a biopesticide and 6 reduced risk fungicides, for control of Phytophthora disease on vinca and pansy. Development of resistance in Phytophthora to mefenoxam fungicides has been documented, and can complicate choosing an effective control strategy. Plants were treated with fungicides and inoculated (sporulating cultures of Phytophthora were flooded to release zoospores for inoculum which was sprayed on the plants until runoff, or injected into the medium at the base of each plant), and evaluated 4-5 days post- spray inoculation and at 15, 21 and 28 days post-injection inoculation. Acrobat/Stature DM 50WP (dimethomorph) significantly reduced Phytophthora disease in all trials; other especially effective products included Aliette 80WDG (fosetyl-al), Subdue MAXX 21.3EC (mefenoxam, reduced risk), Gavel 75DF (mancozeb + zoxamide), Banol 6F (propamocarb), Reason 500SC (reduced risk) and Camelot 58EC (copper salts). Adding new diseases and new crops
to labels will give growers products that can be used in a rotational program when fungicide resistance is a concern, and alternatives to fungicides that are B2 carcinogens. A replicated trial evaluated 4 products, including an experimental and a biopesticide, for control of Botrytis blight on geranium. Development of resistance in B. cinerea to certain classes of fungicides has been documented, and can complicate choosing an effective control strategy. Plants were inoculated, allowed to dry, treated with fungicides, and bagged and placed under shade cloth for the duration of the trial, and rated for disease 10 and 17 days post-inoculation. Only Decree 50WDG (fenhexamid, reduced risk) and Daconil Weather Stik 6F (chlorothalonil, B2 carcinogen) significantly reduced Botrytis infection and disease severity compared to the control; the experimental and Endorse (polyoxin D zinc salt, biopesticide) reduced infection and severity, but the difference was not significant. Adding new
diseases and new crops to labels will give growers products that can be used in a rotational program when fungicide resistance is a concern, and alternatives to fungicides that are B2 carcinogens. C. Significant Activities that Support Special Target Populations: Many greenhouse and nursery operations classify as small farms (< $250, 000 annual gross receipts), and a number of the findings reported here have been communicated directly to farmers or incorporated into specific crop management recommendations that will benefit this and all grower groups. D. Progress Report: This report serves to document research conducted under a Specific Cooperative Agreement between ARS and Michigan State University. As part of the training undertaken by the new Master's student who will investigate environmental manipulation as a management tool for and the epidemiology of Botrytis disease, a comprehensive review of literature concerning Botrytis cinerea research was conducted. 5. Describe the
major accomplishments over the life of the project, including their predicted or actual impact. The plant pathology research accomplishments reported in this section relate to National Program (NP) 303 (Plant Diseases) and represent contributions to research components I (Identification and Classification of Pathogens), II (Biological Control), III (Cultural Control), IV (Pathogen Biology, Genetics, Population Dynamics, Spread, and Relationships with Hosts and Vectors), and V (Host Plant Resistance to Disease). The mammalian herbivore research relates to National Program 304 (Crop Protection and Quarantine) and represents a contribution to research Component V (Pest Control Technologies). Plant Disease Research The most significant findings are that a single isolate of P. nicotianae introduced into a floriculture production facility can (a) spread rapidly throughout the facility/production area via the irrigation water, (b) be very difficult to control using chemical tools, (c) infect
a wide range of hosts, (d) survive extended periods, and (e) be transported to other facilities via infected plants that appear to be healthy. Impact: The epidemiology of Phytophthora within facilities indicates that once an epidemic has been initiated, all plant material that has come into contact with irrigation water used in that facility must be removed and the facility thoroughly sanitized. Selective removal of symptomatic plants will not solve the problem because often infections are quite advanced before symptoms are obvious. Furthermore, the origin of plant material that precedes an epidemic needs to be considered. We have documented the transfer of genetically identical isolates among widely separated facilities through the transfer of seemingly healthy hosts. Producers need to avoid suppliers of infected plant material. And finally, we have isolated a clonal lineage of P. nicotianae from fuchsia that is highly insensitive to the commonly used fungicide mefenoxam.
Dependence on fungicides in lieu of disease free plants and proper sanitation following an epidemic is unlikely to provide satisfactory results. These accomplishments relate to NP 303 Components I, III and IV and project milestones 1a, d. Updated from 2003: Sixty-eight products, including 12 biopesticides and 15 reduced risk fungicides, have been tested in efficacy trials for the control of Phytophthora, Botrytis, and Sphaceloma diseases over the life of this project. Reduced risk and new chemistry fungicides have been identified as effective alternatives to standard products. Impact: Registration of effective reduced risk and new chemistry fungicides and biopesticides would give growers alternatives and/or rotational products to use with industry standards that are B2 carcinogens, especially important if the strains of fungi they are trying to manage have developed resistance to the standard fungicides. These accomplishments relate to NP 303 Components II and III and project
milestone 1e. New methodologies and culture media have been developed and successfully tested to allow isolation, growth and sporulation of S. poinsettiae. Impact: This preliminary information is essential to allow researchers to conduct fungicide efficacy studies, cultivar trials and research into the epidemiology of poinsettia scab. This accomplishment relates to NP 303 Components I and IV and project milestones 1c, e. Eighty-nine poinsettia cultivars were evaluated for resistance to scab, and all varieties developed lesions and were unmarketable. Impact: Growers will need an integrated program which combines effective fungicides and knowledge of the disease cycle of poinsettia scab to manage this disease. This accomplishment relates to NP 303 Component V and project milestone 1d. Mammalian Herbivore Research (Deer and Rodent Repellents) During FY2002 through FY2003, this project supported research on development of herbivore repellents. Funding for this research was discontinued
at the end of FY2003. In studies conducted by S. Ries, R. Baughan, R. Schutzki and R. Beaudry of Michigan State University, volatile compounds were collected from repellent and non-repellent plants using SPME (Solid Phase microextraction) fibers in a closed system. More than 14 plant species were examined over the duration of the herbivore-repellent project, and 24 chemicals, including some promising aromatic oils not currently used in commercial deer and rodent repellents were isolated and identified. A number of these chemicals and combinations of chemicals were formulated and tested in the field. Initial tests indicated potential for use of these materials in developing new more effective and longer-lasting repellents. These contributions relate to NP 304 Component V and project milestones 2a, b, c. 6. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end- user (industry, farmer, other
scientists)? What are the constraints, if known, to the adoption and durability of the technology products? Research results have been disseminated to researchers, growers, and industry representatives through short courses, extension bulletins and other presentations. In particular, floriculturists were informed of the critical importance of sanitation in production systems, risks of mefenoxam resistance, and the efficacy of new, reduced risk products as alternatives to traditional fungicides. This information improves the ability of growers and extension workers to predict and avert disease control failures. One major constraint to implementing effective sanitation practices following a Phytophthora epidemic is that many producers are in production mode year round and it is very difficult to clear all plant material from a facility, sanitize the facility, and then ensure that none of the plant material is returned to the facility ' even if it is apparently healthy. Another problem
facing producers is how to determine that incoming plant material is disease free. Our work suggests that a small number of infected plants may be sufficient to initiate epidemics. The formulation and field evaluation of herbivore repellent chemicals was conducted with industry collaborators from Wisconsin and Pennsylvania. One of the principal constraints to the adoption and durability of herbivore spray-repellent technologies is the capacity of deer and rodents to become accustomed to, and tolerant of, repugnant materials applied to otherwise palatable browse (especially with respect to highly preferred plants). 7. List your most important publications in the popular press and presentations to organizations and articles written about your work. Publications in the Popular Press: Hausbeck, M.K. Tracking Phytophthora. GM Pro. 2003, v. 23(8), p. 68- 70. Hausbeck, M.K. Special Research Report #115: Managing Botrytis blight on poinsettia. American Floral Endowment. 2003.
Available from 'http://www.endowment.org/specialreports/dm.htm'. Hausbeck, M.K. Special Research Report #117: Managing Botrytis blight on geranium. American Floral Endowment. 2003. Available from 'http://www.endowment.org/specialreports/dm.htm'. Hausbeck, M.K, Harlan, B.R. Chemical disease controls for the greenhouse industry. Michigan State University Extension Bulletin E-2750 (poster). 2004. National Presentations: Hausbeck, M.K. Downy mildew and other water molds. Lecture in Bloom, Chicago, IL, June, 2004. Hausbeck, M.K. Downy mildew and other water molds. CAPCA Conference, Carlsbad, CA, June 2004. Hausbeck, M.K. Downy mildew and other water molds. Society of American Florists, 20th Annual Pest Management Conference, San Jose, CA, 2004. Hausbeck, M.K. Tracking the spread of pathogens among and within greenhouses: Phytophthora. American Phytopathological Society Annual Meeting, Charlotte, NC, August, 2003. State Presentations: Hausbeck, M.K. Greenhouse disease
update. Greenhouse Growers Meeting, Wixom, MI, 2004. Hausbeck, M.K. Greenhouse disease management. College of Knowledge, Wayne, MI, 2004. Hausbeck, M.K. Greenhouse disease management. College of Knowledge, Grand Rapids, MI, 2003. Hausbeck, M.K. Disease update on ornamentals. Michigan Greenhouse Growers Expo, Lansing, MI, 2003. Scientific Publications by Collaborators: Hausbeck, M.K., Harlan, B.R. Evaluation of an experimental fungicide and a biopesticide for the control of Botrytis blight of geranium, 2003. Fungicide and Nematicide Tests. 2004. v. 59. p. OT007. Available from 'http://www.apsnet.org/online/FNtests/vol59/top.htm'. Hausbeck, M.K., Harlan, B.R. Evaluation of new products for control of Botrytis on poinsettia, 2003. Fungicide and Nematicide Tests. 2004. v. 59. p. OT008. Available from 'http://www.apsnet. org/online/FNtests/vol59/top.htm'. Hausbeck, M.K., Harlan, B.R., Woodworth, J.A. Evaluation of fungicides and biopesticides for control of Botrytis blight
of geranium, 2003. Fungicide and Nematicide Tests. 2004. v. 59. p. OT006. Available from 'http://www.apsnet.org/online/FNtests/vol59/top.htm'. Hausbeck, M.K., Harlan, B.R., Woodworth, J.A. Evaluation of a biopesticide and fungicides in managing Phytophthora root rot of poinsettia, 2003. Fungicide and Nematicide Tests. 2004. v. 59. p. OT009. Available from 'http://www.apsnet.org/online/FNtests/vol59/top. htm'. Hausbeck, M.K., Harlan, B.R., Woodworth, J.A. Evaluation of fungicides in managing Phytophthora root rot of poinsettia, 2003. Fungicide and Nematicide Tests. 2004. v. 59. p. OT010. Available from 'http://www. apsnet.org/online/FNtests/vol59/top.htm'. Hausbeck, M.K., Harlan, B.R., Woodworth, J.A. Evaluation of fungicides in managing Phytophthora root rot of snapdragon, 2003. Fungicide and Nematicide Tests. 2004. v. 59. p. OT011. Available from 'http://www. apsnet.org/online/FNtests/vol59/top.htm'. Hausbeck, M.K., Harlan, B.R., Woodworth, J.A. Evaluation of
copper and strobilurin fungicides in managing Phytophthora root rot of snapdragon, 2003. Fungicide and Nematicide Tests. 2004. v. 59. p. OT012. Available from 'http://www.apsnet.org/online/FNtests/vol59/top.htm'. Hausbeck, M.K., Woodworth, J.A., Harlan, B.R. Evaluation of a biopesticide and fungicides for managing Phytophthora crown rot of calibrachoa, 2003. Fungicide and Nematicide Tests. 2004. v. 59. p. OT017. Available from 'http://www.apsnet.org/online/FNtests/vol59/top. htm'. Hausbeck, M.K., Woodworth, J.A., Harlan, B.R. Control of Phytophthora aerial blight on vinca with fungicides, 2003. Fungicide and Nematicide Tests. 2004. v. 59. p. OT020. Available from 'http://www.apsnet. org/online/FNtests/vol59/top.htm'. Hausbeck, M.K., Woodworth, J.A., Harlan, B.R., Zalack, J.T. Control of Phytophthora aerial blight with fungicides and experimental products, 2003. Fungicide and Nematicide Tests. 2004. v. 59. p. OT021. Available from
'http://www.apsnet.org/online/FNtests/vol59/top.htm'. Hausbeck, M.K., Woodworth, J.A., Zalack, J. Evaluation of registered and unregistered fungicides in controlling poinsettia scab, 2003. Fungicide and Nematicide Tests. 2004. v. 59. p. OT019. Available from 'http://www. apsnet.org/online/FNtests/vol59/top.htm'. Hausbeck, M.K., Cortright, B.D., Linderman, S.D. Evaluation of registered and unregistered fungicides in managing Botrytis blight of geranium, 2000. Fungicide and Nematicide Tests. 2003. v. 58. p. OT020. Available from 'http://www.apsnet.org/online/FNtests/vol58/top.htm'. Hausbeck, M.K., Cortright, B.D., Linderman, S.D. Evaluation of newly- registered fungicides in managing Botrytis blight of geranium, 2000. Fungicide and Nematicide Tests. 2003. v. 58. p. OT030. Available from 'http://www.apsnet.org/online/FNtests/vol58/top.htm'. Lamour, K.H., Daughtrey, M.L., Benson, D.M., Hwang, J., Hausbeck, M.K. Etiology of Phytophthora drechsleri and P. nicotianae (=P.
parasitica) diseases affecting floriculture crops. Abstract. Phytopathology. 2003. v. 93. p. S118. Publication no. P-2003-0146-SSA. Available from 'http://www.apsnet.org/meetings/2003/abstracts/se03ma146.htm'.
Impacts
(N/A)
Publications
- Hausbeck, M.K., Linderman, S. D. Evaluation of fungicides in managing Botrytis blight of geranium, 2000. Fungicide and Nematicide Tests. 2002. v. 57. p. OT11.
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Progress 10/01/02 to 09/30/03
Outputs
1. What major problem or issue is being resolved and how are you resolving it? Greenhouse-grown floricultural crops are constantly being threatened by the plant pathogenic fungus Botrytis cinerea, which causes gray mold or Botrytis blight. The wet, humid greenhouse environment favors rapid growth and prolific sporulation of B. cinerea, and Botrytis blight continues to cause significant losses at all stages of floriculture production. Phytophthora crown and root rot of ornamentals is caused by Phytophthora spp., fungi that produce sporangia which are able to release swimming spores upon immersion in water. Sporangia likely play a major role in epidemics, spreading disease from initial points of infection. Poinsettias accounted for the largest value of wholesale potted flowering plant sales in 2000 for the state of Michigan and the U.S., and the national value of the crop has been steadily increasing. Poinsettia scab, (causal agent, Sphaceloma poinsettiae), a
disease that is spread by water, has become more prevalent in the U.S. as the result of a recent shift towards the production of poinsettia stock plants in Central America, where S. poinsettiae naturally occurs. The objectives of this cooperative research project are to: 1) Identify the major Phytophthora spp. affecting floriculture production and determine which aspects of Phytophthora's life history contribute significantly to control failure, 2) Determine the role of environment in the disease cycle of B. cinerea and investigate environmental manipulation as a viable management tool for flower and leaf blight, 3) Determine the role of the environment in the disease cycle of S. poinsettiae, 4) Develop durable production strategies for preventing and eliminating disease caused by Phytophthora spp., B. cinerea, and S. poinsettiae on floriculture hosts, and 5) Screen novel agents for their potential as management tools for control of Phytophthora crown and root rot disease, Botrytis
flower and leaf blight, and poinsettia scab. 2. How serious is the problem? Why does it matter? The seriousness of the problem due to Phytophthora infection varies according to production facility. We have characterized approximately 15 Phytophthora epidemics and the damages range from relatively minor (infection confined to limited foci) to quite serious (50-60% of the grower's production lost to Phytophthora with a value in excess of $200, 000). A better understanding of which Phytophthora spp. are causing problems and how the populations are distributed in space and time provides useful information for developing management strategies. Many important floricultural crops are susceptible to Botrytis, with certain plants and plant parts being highly susceptible, and the age of the plants also playing a factor in infection. Thus, Botrytis infection can occur as leaf spots; blighting; stem cankers; rots of corms, rhizomes, tubers and seeds; and pre- or postemergence damping off.
Disease can occur during seed, plug, bedding plant or potted plant production, stock plant and cuttings production, and storage and/or shipment of cuttings and cut flowers. Botrytis conidia can be released into the greenhouse atmosphere during any grower activity which disturbs the plants, including irrigating, spraying pesticides, and harvesting cuttings; natural release occurs approximately midmorning and mid-afternoon and coincides with a rapid decrease in relative humidity. A conidium may survive for at least three weeks before germination, and may potentially be shipped from greenhouse to greenhouse. Failure to control Botrytis at one production stage in any crop can have negative ramifications for subsequent stages and other susceptible crops in the same facility. Development of resistance in B. cinerea to certain classes of fungicides can complicate choosing an effective control strategy. Poinsettia scab is the limiting factor in the outdoor production of poinsettias in
tropical areas of the U.S. since its discovery in the early 1940s in Florida and Hawaii. The pathogen causes lesions on the stems, leaves and petioles of poinsettias, rendering the plants unmarketable. In severe cases, defoliation, girdling or elongation of stems may occur. Virtually no research has been conducted on the epidemiology of this fungus due to the fact that scab has been managed successfully in the past by use of clean stock plant materials. The recent shift in poinsettia stock plant production to Central America, where the pathogen is indigenous, has resulted in outbreaks of scab in U. S. greenhouses. Growers in the U.S. need management strategies for this new disease of poinsettias to produce a quality crop for consumers. Animal damage totals millions of dollars in losses to growers. Damage to Michigan apples alone amounts to $1.4 million for growers already spending nearly $600,000 for prevention. Deer, feeding on hay and corn stored for cattle feed and also
mingling with cattle, have contributed to the spread of tuberculosis. An inexpensive, practical and easily applied animal repellent also would relieve much of the tension among special interest groups for or against high deer populations. 3. How does it relate to the National Program(s) and National Program Component(s) to which it has been assigned? National Program: 304 (Crop Protection and Quarantine) 100%. Research under this project improves our understanding of the taxonomy, biology, ecology and epidemiology of plant pathogens. The primary objective is development of safe, effective methods and strategies for sustainable integrated management of several key diseases of ornamental horticulture. Research conducted under this project that relates to plant pathogen identification, biology, ecology and epidemiology contributes significantly to National Program 303, Plant Diseases. One of the principal objectives of this project, development of methods and strategies for integrated
management of root rot diseases of floral and nursery crops, is also being pursued through two additional Specific Cooperative Agreements. An agreement with Cornell University (J. Sanderson, CDR) includes, as one component, studies of various soil factors affecting survival, dispersal and control of Pythium pathogens and assessments of numerous Pythium species and strains for fungicide resistance. A second agreement with Cornell University (M. Daughtrey, CDR) aims to develop basic techniques for identification and characterization of Pythium and Phytophthora root rot diseases and to use these tools to develop or improve integrated disease management techniques. 4. What were the most significant accomplishments this past year? A. Single most significant accomplishment during FY 2003. Epidemics of Phytophthora disease in floriculture facilities can be very devastating and can put other current and future susceptible crops at risk. Diseased plant samples collected at Cornell
University, North Carolina State University and Michigan State University, were described according to compatibility type, resistance to mefenoxam, and amplified fragment length polymorphism profiles in the laboratory at Michigan State. This research, published in Plant Disease, gives an overall view of U.S. floriculture production, and documents the spread of Phytophthora spp. between facilities, the importance of asexual reproduction in the occurrence of epidemics, the persistence of one clone at one site over two years, and the development of fungicide resistance in the pathogens. This research emphasizes the need for growers to implement disease management techniques for Phytophthora that include scouting both newly arrived plant material and crops in production for signs of disease, and quick treatment of diseased crops with fungicides that are effective at controlling the disease. B. Other significant accomplishments (if any): Plant Disease Research: Over the course of this
project we have screened 515 isolates of P. nicotianae and P. drechsleri from snapdragon, poinsettia, calibrochoa, vinca, fuschia, bacopa, verbena, african violet and dusty miller from various facilities in the USA for sensitivity to the commonly used fungicide mefenoxam. This work was conducted by researchers at Michigan State University. Of these 515 Phytophthora isolates, 375 were sensitive, 43 were intermediately sensitive and 94 were found to be fully insensitive to a dosage of mefenoxam. This indicates that the spread of mefenoxam-insensitive Phytophthora isolates may significantly reduce the efficacy of this fungicide. Reducing fungicide use is a goal of growers and consumers, and finding disease resistance in cultivars of susceptible crops can contribute toward that goal. A trial was conducted in the research greenhouses at Michigan State University evaluating the susceptibility of 32 poinsettia cultivars to root rots caused by P. drechsleri and P. nicotianae. Phytophthora
drechsleri was identified as a particularly virulent pathogen of poinsettia, with 100% death occurring in 20 of the 32 cultivars, while P. nicotianae caused up to 50% death among 9 out of the 32 cultivars. Although there were some differences in susceptibility among the cultivars, there were no cultivars that were completely resistant to Phytophthora rot; this shows the critical need for other effective disease management tools for growers. The Horticulture Demonstration Gardens at Michigan State University were experiencing disease epidemics suspected to be caused by Phytophthora. On two occasions, a research assistant sampled diseased plants of vinca (originally from a California grower) and calibrochoa (from a Pennsylvania grower), and identified the pathogen isolates by internal transcribed sequence (ITS) sequencing and characterized their sensitivity to mefenoxam. Eight samples from vinca were infected with P. drechsleri that were sensitive to mefenoxam; and 13 samples from
calibrochoa were P. nicotianae that were insensitive to mefenoxam. This confirms that asympomatic infected plants can be shipped from one facility to another and subsequently be the cause of an epidemic; thus, control of Phytophthora at the level of the producers is essential to ensure consumer satisfaction. Growers rely heavily on synthetic chemical fungicides for disease control, and depend on agricultural researchers to make recommendations for their use and for research on fungicide effectiveness which can support labeling of these products for new crops. Twenty-one products were tested for control of Phytophthora crown and root rot on poinsettia, calibrochoa, snapdragon and vinca in the research greenhouses at Michigan State University. Although different crops appeared to differ in susceptibility, Acrobat 50WP (dimethomorph), Aliette 80WDG (fosetyl-al), Banol 66.5EC (propamocarb), Banrot 40WP (etridiazole + thiophanate-methyl) , BAS 516 38WG (boscalid + pyraclostrobin),
Camelot 58EC (copper), Ranman 3.3SC (cyazofamid), Reason 4.17SC (fenamidone), Stature DM 50WP (dimethomorph + mancozeb), Subdue MAXX 22.5EC (mefenoxam), Truban 30WP (etridiazole), and Truban alternated with 710-145f 0.13% (Bacillus licheniformis) showed effectiveness at managing Phytophthora rot. Banol, BAS 516, Ranman, Reason, and Subdue MAXX are reduced risk or candidate reduced risk fungicides, and 710-145f is a biopesticide; these products can serve as alternatives to industry standards that are: (a) carcinogenic and thus at risk due to the Food Quality Protection Act (FQPA), or (b) ineffective due to resistance which has developed in the Phytophthora pathogens. Research on fungicide effectiveness can support labeling of these products for new crops, thus the efficacy of eight products were tested to identify alternatives to the industry standards used by growers for control of Botrytis blight. Two trials were conducted in the research greenhouses at Michigan State University on
poinsettia and geranium. Daconil 6F (chlorothalonil) and Decree 50WDG (fenhexamid) were especially effective for all parameters measured, while Chipco 26019 (iprodione), Endorse 2.4WP (polyoxin D zinc salt), Endorse alternate 710-145f (Bacillus licheniformis), and Insignia (pyraclostrobin) showed significant differences for some of the parameters measured in these Botrytis trials. Decree and Insignia are reduced risk fungicides and 710- 145f is a biopesticide; these products can serve as alternatives to industry standards that are: a) carcinogenic and thus at risk due to FQPA, or b) ineffective due to resistance which has developed in B. cinerea. Little previous research had been done on the methodology of culturing and inoculating S. poinsettiae, knowledge which is required to manipulate and maintain the fungus for long term studies. Research was initiated at Michigan State University to identify media types that allow successful isolation and sporulation of S. poinsettiae in
vitro. Potato dextrose agar amended with antibiotics proved essential for the rapid identification and isolation of S. poinsettiae, while a corn husk medium allowed for the production of spores of this slow-growing fungus within a one-week period. The success of these media and methodologies has allowed for studies to be undertaken at Michigan State University and other institutions on fungicide efficacy, cultivar resistance, and epidemiology. Identifying the environmental conditions that lead to the infection and spread of S. poinsettiae will be useful in developing long-term management strategies in propagation facilities and production greenhouses. Research into the spread of poinsettia scab under irrigation and elevated humidity conditions is currently underway at Michigan State University. Poinsettias have been successfully inoculated, and environmental parameters and spore releases are being monitored to determine the environmental factors which favor dissemination of S.
poinsettiae. Knowledge of the epidemiology of poinsettia scab will allow growers, with the aid of weather monitoring equipment, to identify when conditions are favorable for disease development, and thus efficiently target disease scouting and initiation of fungicide spray programs. Testing poinsettia cultivars for resistance to scab, caused by S. poinsettiae, could identify varieties that would need fewer fungicide applications to manage poinsettia scab. A trial evaluating the susceptibility of 57 poinsettia cultivars to poinsettia scab was conducted at Michigan State University. All cultivars developed lesions on stems, leaves and petioles, although the data has not been analyzed statistically yet. The susceptibility of all 57 cultivars to scab emphasizes the need for effective fungicide control until other methods of control can be identified. Mammalian Herbivore Research (Deer and Rodent Repellents): It was postulated that volatile compounds are among the primary factors in
plants responsible for repelling deer and other mammalian herbivores. In studies conducted by researchers at Michigan State University, volatile compounds were collected from repellent and non-repellent plants using SPME (Solid Phase microextraction) fibers in a closed system; subsequent research then focused on compounds found only in repellent plants. Twenty-four chemicals were identified, including some aromatic oils not currently used in commercial repellents. Field evaluations of these previously untested chemicals and novel chemical mixtures have been initiated, and this research is expected to result in development of improved deer repellent formulations. C. Significant activities that support special target populations. Many greenhouse and nursery operations can be classified as small farms (< $250,000 annual gross receipts), and a number of the findings reported here have been communicated directly to farmers or incorporated into specific crop management recommendations
that will benefit small farms and all grower groups. 5. Describe the major accomplishments over the life of the project, including their predicted or actual impact. The most significant findings are that a single isolate of P. nicotianae introduced into a floriculture production facility can (a) spread rapidly throughout the facility/production area via the irrigation water, (b) be very difficult to control using chemical tools, (c) infect a wide range of hosts, (d) survive extended periods, and (e) be transported to other facilities via infected plants that appear to be healthy. Impact: The epidemiology of Phytophthora within facilities indicates that once an epidemic has been initiated that all of the plant material that has come into contact with irrigation water used in that facility must be removed and the facility thoroughly sanitized. Roguing symptomatic plants will not solve the problem because often infections are quite advanced before symptoms are obvious. Furthermore,
the origin of plant material that precedes an epidemic needs to be considered. We have documented the transfer of genetically identical isolates among widely separated facilities through the transfer of seemingly healthy hosts. Producers need to avoid suppliers of infected plant material. And finally, we have isolated a clonal lineage of P. nicotianae from fuchsia that is highly insensitive to the commonly used fungicide mefenoxam. Dependence on fungicides in lieu of disease free plants and proper sanitation following an epidemic is unlikely to provide satisfactory results. Updated from 2002: Sixty products have been tested in efficacy trials for the control of Phytophthora rot and Botrytis blight over the life of this project. Reduced risk and new chemistry fungicides have been identified as effective alternatives to standard products. Registration of effective reduced risk and new chemistry fungicides would give growers alternatives to industry standards, especially if the
strains of fungi they are trying to manage have developed resistance to the standard fungicides. New methodologies and culture media have been developed and successfully tested to allow isolation, growth and sporulation of S. poinsettiae. This preliminary information is essential to allow researchers to conduct fungicide efficacy studies and research into the epidemiology of poinsettia scab. More than 14 plant species have been examined over the duration of the herbivore-repellent project. Twenty-four chemicals, including some promising aromatic oils, which are not currently used in commercial deer and rodent repellents have been isolated and identified. Continued research with these chemicals and with other repellent compounds as yet unidentified are expected to yield a cost effective product suitable for commercial applications. 6. What do you expect to accomplish, year by year, over the next 3 years? Research results from 2003-04 will be presented at meetings and trade shows, and
published in refereed journals as appropriate. Phytophthora 2003-04: Determine efficacy of currently registered and unregistered pesticides including biocontrol agents and reduced risk products for control of Phytophthora crown and root rot. Botrytis 2003-04: Quantify the influence of the environment (temperature, relative humidity, and duration of leaf wetness) on the infection, colonization, and reproductive processes of Botrytis. Develop methodologies and determine the appropriate timing of environmental manipulation as a means of averting or interrupting a Botrytis disease epidemic. Determine efficacy of currently registered and unregistered pesticides including biocontrol agents and reduced risk products for control of Botrytis flower and leaf blight. Sphaceloma 2003-04: Determine leaf wetness durations and temperatures which promote disease expression on poinsettia in growth chambers by observing symptoms after 14 days of (a) varying the temperatures (20, 25, 30, 35 C) with 24
hours of leaf wetness, and (b) varying leaf wetness duration at the most favorable temperature determined in (a). Determine the environmental parameters (temperature, humidity, light) which influence the production of colored and hyaline conidia produced by inoculated tissue incubated in environmental chambers. Determine methods of scab control by (a) testing efficacy of currently registered and unregistered pesticides including biocontrol agents and reduced risk products, and (b) evaluating resistance of 40 poinsettia cultivars to scab. 7. What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end- user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? Research results have been disseminated to researchers, growers, and industry representatives through short courses, extension bulletins and other presentations. In
particular, floriculturists were informed of the critical importance of sanitation in production systems, risks of mefenoxam resistance, and the efficacy of new, reduced risk products as alternatives to traditional fungicides. This information improves the ability of growers and extension workers to predict and avert disease control failures. One major constraint to implementing effective sanitation practices following a Phytophthora epidemic is that many producers are in production mode year round and it is very difficult to clear all plant material from a facility, sanitize the facility, and then ensure that none of the plant material is returned to the facility - even if it is apparently healthy. Another problem facing producers is how to determine that incoming plant material is disease free. Our work suggests that a small number of infected plants may be sufficient to initiate epidemics. The effectiveness (or lack of effectiveness) of commercial deer and rodent repellent
formulations was communicated to each of the 14 companies that providing animal repellents for field tests. 8. List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: This does not replace your peer-reviewed publications listed below). Publications in the Popular Press: Hausbeck, M.K, Harlan, B.R. Chemical Controls for the Greenhouse Industry. Michigan State University Extension Bulletin E-2750 (poster). 2003. Hausbeck, M.K. Tips for managing Botrytis: Comparing chemical controls. GM Pro. 2002. v. 22(12). p. 59-60. Deer Repellent Research Encouraging. Michigan Landscape. v. 2003. 46(1). p. 40-42. National Presentations: Hausbeck, M.K. Control of Botrytis diseases and poinsettia scab on floral crops. Floriculture and Nursery Research Initiative Researchers Meeting. Raleigh, NC. March, 2003. Hausbeck, M.K. Control of Phytophthora diseases on floral crops. Floriculture and Nursery Research Initiative
Researchers Meeting. Raleigh, NC. March, 2003. Hausbeck, M.K. Greenhouse disease management. College of Knowledge, Ohio Florists' Short Course, sponsored by the Ohio Florists' Association. Columbus, OH. 2002. State Presentations: Hausbeck, M.K. New tools for management of diseases in the greenhouse. Greenhouse Growers' Meeting. Macomb, MI. 2003. Hausbeck, M.K. Managing greenhouse diseases with new tools. Greenhouse Growers' Meeting. Grandville, MI. 2003. Hausbeck, M.K. Greenhouse disease management. College of Knowledge. Fall Ornamentals Program. Michigan Greenhouse Growers Expo. Lansing, MI. 2002. Scientific Publications: Hausbeck, M.K., Cortright, B.D., Werner, N.A. Evaluation of registered and unregistered fungicides in managing Botrytis blight of geranium, 2000. Fungicide and Nematicide Tests. 2003. v. 58. p. OT033. Available from http://www.apsnet.org/online/FNtests/vol58/top.htm. Hausbeck, M.K., Harlan, B.R., Linderman, S.D. Evaluation of registered and unregistered fungicides
in managing Phytophthora root rot of snapdragon, 2002. Fungicide and Nematicide Tests. 2003. v. 58. p. OT018. Available from http://www.apsnet.org/online/FNtests/vol58/top.htm. Hausbeck, M.K., Harlan, B.R., Linderman, S.D. Evaluation of fungicides in managing Phytophthora root rot of snapdragon, 2002. Fungicide and Nematicide Tests. 2003. v. 58. p. OT019. Available from http://www.apsnet. org/online/FNtests/vol58/top.htm. Hausbeck, M.K., Harlan, B.R., Linderman, S.D. Evaluation of reduced risk fungicides and a biopesticide for control of Botrytis blight of geranium, 2002. Fungicide and Nematicide Tests. 2003. v. 58. p. OT029. Available from http://www.apsnet.org/online/FNtests/vol58/top.htm. Hausbeck, M.K., Quackenbush, W., Linderman, S.D. Evaluation of standard fungicides and a biological control agent in managing Botrytis blight of geranium, 2002. Fungicide and Nematicide Tests. 2003. v. 58. p. OT031. Available from http://www.apsnet.org/online/FNtests/vol58/top.htm. Hausbeck, M.K.,
Quackenbush, W., Linderman, S.D. Evaluation of biopesticide for control of Botrytis blight of geranium, 2002. Fungicide and Nematicide Tests. 2003. v. 58. p. OT028. Available from http://www. apsnet.org/online/FNtests/vol58/top.htm. Hausbeck, M.K., Quackenbush, W., Linderman, S.D. Evaluation of registered and unregistered fungicides for the control of Botrytis blight of poinsettia, 2001. Fungicide and Nematicide Tests. 2003. v. 58. p. OT016. Available from http://www.apsnet.org/online/FNtests/vol58/top.htm. Hausbeck, M.K., Wendling, N., Werner, N.A. Evaluation of registered and unregistered fungicides in managing Botrytis blight of geranium, 2001. Fungicide and Nematicide Tests. 2003. v. 58. p. OT032. Available from http://www.apsnet.org/online/FNtests/vol58/top.htm. Hausbeck, M.K., Wendling, N., Werner, N.A. Evaluation of a reduced risk fungicide in managing Botrytis blight of geranium, 2001. Fungicide and Nematicide Tests. 2003. v. 58. p. OT027. Available from http://www.apsnet.
org/online/FNtests/vol58/top.htm. Hausbeck, M.K., Werner, N.A., Harlan, B.R. Evaluation of registered and unregistered fungicides and biological agents in managing Phytophthora root rot of snapdragon, 2001. Fungicide and Nematicide Tests. 2003. v. 58. p. OT017. Available from http://www.apsnet. org/online/FNtests/vol58/top.htm. Hausbeck, M.K., Woodworth, J. Evaluation of fungicides in managing Phytophthora root rot of poinsettia, 2002. Fungicide and Nematicide Tests. 2003. v. 58. p. OT026. Available from http://www.apsnet. org/online/FNtests/vol58/top.htm. Lamour, K.H., Daughtrey, M.L., Benson, D.M., Hwang, J., Hausbeck, M.K. Etiology of Phytophthora drechsleri and P. nicotianae (= P. parasitica) diseases affecting floriculture crops. Plant Disease. 2003. v. 87. p. 854- 858. Woodworth, J., Hausbeck, M.K. Comparison of cultivar susceptibility to Phytophthora root rots of poinsettia, 2002. Biological and Cultural Tests. 2003. v. 18. p. O006. Available from http://www.apsnet.
org/online/BCtests/Vol18/top.htm.
Impacts
(N/A)
Publications
- Hausbeck, M.K., Linderman, S. D. Evaluation of fungicides in managing Botrytis blight of geranium, 2000. Fungicide and Nematicide Tests. 2002. v. 57. p. OT11.
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Progress 10/01/01 to 09/30/02
Outputs
1. What major problem or issue is being resolved and how are you resolving it? Greenhouse-grown floricultural crops are constantly being threatened by the plant pathogenic fungus Botrytis cinerea, which causes gray mold or Botrytis blight. The wet, humid greenhouse environment favors rapid growth and prolific sporulation of B. cinerea, and Botrytis blight continues to cause significant losses at all stages of floriculture production. Phytophthora crown and root rot of ornamentals is caused by Phytophthora spp., fungi that produce sporangia which are able to release swimming spores upon immersion in water. Sporangia likely play a major role in epidemics, spreading disease from initial points of infection. The objectives of this cooperative research project are to: 1) Identify the major Phytophthora spp. affecting floriculture production and determine which aspects of Phytophthora's life history contribute significantly to control failure, 2) Determine the role of
environment in the disease cycle of Botrytis and investigate environmental manipulation as a viable management tool for flower and leaf blight, 3) Develop durable production strategies for preventing and eliminating disease caused by Phytophthora spp. and Botrytis on floriculture hosts, and 4) Screen novel agents for their potential as management tools for control of Phytophthora crown and root rot disease and Botrytis flower and leaf blight. 2. How serious is the problem? Why does it matter? The seriousness of the problem due to Phytophthora infection varies according to production facility. We have characterized approximately 15 Phytophthora epidemics and the damages range from relatively minor (infection confined to limited foci) to quite serious (50-60% of the grower's production lost to Phytophthora with a value in excess of $200, 000). A better understanding of which Phytophthora spp. are causing problems and how the populations are distributed in space and time provides
useful information for developing management strategies. Many important floricultural crops are susceptible to Botrytis, with certain plants and plant parts being highly susceptible, and the age of the plants also playing a factor in infection. Thus, Botrytis infection can occur as leaf spots, blighting, stem cankers, rots of corms, rhizomes, tubers and seeds; and pre- or post-emergence damping off. Disease can occur during seed, plug, bedding plant or potted plant production, stock plant and cuttings production, and storage and/or shipment of cuttings and cut flowers. Botrytis conidia can be released into the greenhouse atmosphere during any grower activity which disturbs the plants, including irrigating, spraying pesticides, and harvesting cuttings; natural release occurs approximately midmorning and mid-afternoon and coincides with a rapid decrease in relative humidity. A conidium may survive for at lease three weeks before germination, and may potentially be shipped from
greenhouse to greenhouse. Failure to control Botrytis at one production stage in any crop can have negative ramifications for subsequent stages and other susceptible crops in the same facility. Development of resistance in B. cinerea to certain classes of fungicides can complicate choosing an effective control strategy. 3. How does it relate to the national Program(s) and National Program Component(s) to which it has been assigned? National Program: 304 - Crop Protection and Quarantine - 100% Research under this project improves our understanding of the taxonomy, biology, ecology and epidemiology of plant pathogens. The primary objective is development of safe, effective methods and strategies for sustainable integrated management of several key diseases of ornamental horticulture. Research conducted under this project that relates to plant pathogen identification, biology, ecology and epidemiology contributes significantly to National Program 303, Plant Diseases. One of the
principal objectives of this project, development of methods and strategies for integrated management of root rot diseases of floral and nursery crops, is also being pursued through two additional Specific Cooperative Agreements. An agreement with Cornell University (J. Sanderson, CDR) includes, as one component, studies of various soil factors affecting survival, dispersal and control of Pythium pathogens and assessments of numerous Pythium species and strains for fungicide resistance. A second agreement with Cornell University (M. Daughtrey, CDR) aims to develop basic techniques for identification and characterization of Pythium and Phytophthora root rot diseases and to use these tools to develop or improve integrated disease management techniques. 4. What was your most significant accomplishment this past year? A. Single Most Significant Accomplishment during FY 2002: Studies of the population dynamics of plant pathogens are needed to elucidate mechanisms of disease spread within
and among greenhouse production facilities. We tracked the genetic diversity of a Phytophthora nicotianae population causing serious problems to snapdragon production at a facility in the south central region of the U.S. to determine if isolates were persisting over time (years) or if multiple introductions of Phytophthora were occurring; samples were processed and analyzed at Michigan State University (MSU) in the laboratory of M.K. Hausbeck. Full analysis of the isolates collected in 2002 is continuing. However, preliminary results indicate that a single clonal lineage of P. nicotianae, which caused significant problems during 2000 and 2001, was again present in 2002. Thus, a small introduction event (e.g.; introduction of a single diseased plant) may lead to serious long-term problems. These findings support efforts by managers to devise robust plans for avoiding the introduction of Phytophthora into production facilities and underscores the need for absolute sanitization if
eradication of an epidemic is to be effective. B. Other Significant Accomplishment(s), if any: Investigations of plant pathogen population dynamics also resulted in identification of a unique clonal lineage of P. nicotianae common to three floriculture production facilities in the north central region of the U.S. that was likely spread via infected plant material. Collection of isolates and genetic analysis were conducted in the laboratory of M.K. Hausbeck at MSU. This aspect of the study specifically shows how Phytophthora may be introduced to a facility and documents how a problem at an early stage of the production pipeline can lead to significant problems downstream. Fungicide resistance is one of the most difficult problems in disease management; development of resistance by a key pathogen to even a single widely used fungicide can translate into substantial economic losses. Over the course of this project we have screened more than 500 isolates of Phytophthora from diverse
facilities for sensitivity to the commonly used fungicide mefenoxam. This work was conducted in the laboratory of M. K. Hausbeck at MSU. Two populations of Phytophthora were found to be either intermediately or fully insensitive to mefenoxam. Identification of mefenoxam-insensitive isolates enables selection of alternative control agents, preventing economic loss due to crop failure and also saving growers the expense of making ineffective applications. Growers rely heavily on synthetic chemical fungicides for disease control and depend on agricultural researchers to make recommendations on their use. Research on fungicide effectiveness also supports labeling of these products for new crops. The efficacies of nine products were tested for control of Phytophthora crown and root rot on snapdragon. Three trials were conducted in the research greenhouse of M.K. Hausbeck at MSU. Ardent 50WP (kresoxim-methyl), Stature 69WP (dimethomorph + mancozeb), and Subdue MAXX 21.3EC (mefenoxam)
showed effectiveness against Phytophthora. Ardent is a reduced risk fungicide which can offer growers an alternative to carcinogenic fungicides at risk due to the Food Quality Protection Act (FQPA). The efficacy of 17 products was tested for control of Botrytis blight on geranium. Three trials were conducted in the research greenhouse of M.K. Hausbeck at MSU. BAS 51070WG, Chipco 26GT (iprodione), Compass 50WG (trifloxystrobin) alone or in combination with Latron B-1956, Daconil Weatherstik (chlorothalonil), Decree 50WDG (fenhexamid), Echo 720 (chlorothalonil), Endorse WP (polyoxin D zinc salt), Spectro 90 (chlorothalonil + thiophanate-methyl) showed effectiveness against Botrytis. BAS 510 70WDG, Compass 50WG and Decree 50WDG are reduced risk fungicides which can offer growers alternatives to carcinogenic fungicides at risk due to the FQPA. C. Significant Activities that Support Special Target Populations: Many greenhouse and nursery operations classify as small farms (< $250, 000
annual gross receipts), and a number of the findings reported here already have been incorporated into specific crop management recommendations that will benefit this and all grower groups (see question 7). 5. Describe your major accomplishments over the life of the project, including their predicted or actual impact? The most significant findings are that a single isolate of P. nicotianae introduced into a floriculture production facility can (i) spread rapidly throughout the facility/production area via the irrigation water, (ii) be very difficult to control using chemical tools, (iii) infect a wide range of hosts, (iv) survive extended periods, and (v) be transported to other facilities via infected plants that appear to be healthy. Impact: The epidemiology of Phytophthora within facilities indicates that once an epidemic has been initiated, all of the plant material that has come into contact with irrigation water used in that facility must be removed and the facility thoroughly
sanitized. Roguing symptomatic plants will not solve the problem because often infections are quite advanced before symptoms are obvious. Furthermore, the origin of plant material that precedes an epidemic needs to be considered. We have documented the transfer of genetically identical isolates among widely separated facilities through the transfer of seemingly healthy hosts. Producers need to avoid suppliers of infected plant material. And finally, we have isolated a clonal lineage of P. nicotianae from fuchsia that is highly insensitive to the commonly used fungicide mefenoxam. Dependence on fungicides in lieu of disease free plants and proper sanitation following an epidemic is unlikely to provide satisfactory results. Forty-seven products have been tested in efficacy trials for the control of Phytophthora rot and Botrytis blight over the life of this project. Reduced risk and new chemistry fungicides have been identified as effective alternatives to standard products. 6.
What do you expect to accomplish, year by year, over the next 3 years? The existing Specific Cooperative Agreement is funded on an annual basis, and funding is anticipated for an additional year (through September 2003) . Phytophthora (2002-2003): Continue characterizing Phytophthora populations within and among production facilities throughout the United States, focusing on sites with a history of Phytophthora problems in order to determine how long a clonal lineage can persist. Determine the incidence and document symptoms of various Phytophthora spp. on specific floriculture crops. On those Phytophthora spp. determined to be most common among floriculture crops, define reproductive characteristics (homothallic vs. heterothallic) including mating type (A1 or A2) if appropriate, and sensitivity to the synthetic, systemic, fungicide mefenoxam. Utilize DNA fingerprinting techniques (AFLP) to characterize and track Phytophthora populations and determine its usefulness in determining
potential sources of inoculum. Determine efficacy of currently registered and unregistered pesticides including biocontrol agents for control of Phytophthora crown and root rot. Botrytis (2002-2003): Determine efficacy of currently registered and unregistered pesticides including biocontrol agents for control of Botrytis flower and leaf blight. Quantify the influence of the environment (temperature, relative humidity, and duration of leaf wetness) on the infection, colonization, and reproductive processes of Botrytis. Develop methodologies and determine the appropriate timing of environmental manipulation as a means of averting or interrupting a Botrytis disease epidemic. Wild Herbivore Research: Funding for this cooperative agreement has been increased for FY2003 to support new research on control of deer and rabbit herbivory on ornamental plants. Objectives for FY2003 and 2004 included: Isolation of non-volatile repellant compounds from browse-resistant plant species by sequential
extraction with organic solvents. Isolation of volatile compounds using microextraction protocols with analysis by gas chromatography and mass spectroscopy. Bioassays of new compounds. Evaluations of phytotoxicity of the most promising repellant compounds. Development of formulations that will resist breakdown by the environment and release repellant compounds at an active rate. Test slow-release formulations of repellants developed in cooperation with Liphatech, a Wisconsin Company and Hercon Corp. of Pennsylvania. 7. What technologies have been transferred and to whom? When is the technology likely to become available to the end user (industry, farmer other scientist)? What are the constraints, if known, to the adoption durability of the technology? Findings reported here have been communicated to growers, researchers and extension agents and are being incorporated into new recommendations for Phytophthora disease forecasting and management. The importance of production facility
sanitation has been emphasized, and rigorous standards for sanitation have been proposed. One major constraint to implementing these practices following a Phytophthora epidemic is that many producers are in production mode year round and it is very difficult to clear all plant material from a facility, sanitize the facility, and then ensure that none of the plant material is returned to the facility - even if it is apparently healthy. Another problem facing producers is how to determine that incoming plant material is disease free. Our work suggests that a small number of infected plants may be sufficient to initiate epidemics. 8. List your most important publications and presentations, and articles written about your work (NOTE: this does not replace your review publications which are listed below) Hausbeck, M.K. Management strategies for fighting Phytophthora. GM Pro. 2001. v. 21(8). p. 75-76. Hausbeck, M.K. "New products for disease control," presented at the Ohio Florists'
Short Course, sponsored by the Ohio Florists' Association, Columbus, OH, 2001.
Impacts
(N/A)
Publications
- Hausbeck, M.K., Linderman, S. D. Evaluation of fungicides in managing Botrytis blight of geranium, 2000. Fungicide and Nematicide Tests. 2002. v. 57. p. OT11.
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