Progress 09/01/07 to 08/31/10
Outputs
OUTPUTS: Michigan researchers established experiments for management of Phytophthora root and crown rot and common weed control on squash and pepper for years 2008-2010 using large-scale replicated demonstration field trials in grower-cooperators' fields. Each experiment was conducted in a field with a known history of disease and weed pressure. Studies compared reduced rates of registered fumigants, including methyl bromide/chloropicrin (MB/pic), metam potassium, chloropicrin, dichloropropene, and iodomethane, applied under virtually impermeable film (VIF) versus full fumigant rates under low density polyethylene (LDPE). Two additional studies compared the efficacy of the newly registered Paladin (dimethyl disulfide) fumigant with MB/chloropicrin for the control of Phytophthora on yellow squash. The effects of fumigants applied under LDPE and VIF mulches on weeds were assessed at two sites by (i) assessing changes in the viability of buried weed seeds, and (ii) evaluating the density of native weeds emerging from planting holes or breaking through plastic. Three studies examined the effectiveness of fungicides to control Phytophthora capsici affecting peppers when applied through drip tape. Two other studies compared the effectiveness of fungicides for the control of P. capsici on yellow squash when applied by drench versus being applied as a foliar application. Work continued on developing a protocol using real-time polymerase chain reaction (PCR) to improve the method of P. capsici detection and quantification in soil. The method of real-time PCR involves extracting DNA from sampled soil with a commercial DNA extract kit, and running PCR with pre-designed primers. A set of primers were designed based on the internal transcribed spacer region of the ribosomal DNA that is unique for P. capsici. The method is specific to P. capsici and was tested on five P. capsici isolates and samples of 14 other Phytophthora spp. and Pythium sp. The method was tested across three types of soils (sandy loam, clay, muck soil) that were spiked with same amount of P. capsici zoospores. Six Michigan growers signed up for the irrigation monitoring service offered by the Southwest Irrigation Network in 2008-2010. Crops monitored included cucumber, eggplant, hard squash, pepper, tomato, and yellow squash/zucchini for a total of 62 sites. Soil moisture was monitored weekly during the growing season. Plant stage and weather data was entered into the scheduling program and results indicating length of irrigation times for their crops faxed to each grower along with the current soil moisture information. Information on this research has been posted to the website http://veggies.msu.edu/MBTPhytophthora/MBT-Phytophthora-home.htm. Grant objectives were discussed with grower input at the SW Michigan Vegetable Advisory Meeting held in Dec 2009 and yearly at the Great Lakes Expo. PARTICIPANTS: Dr. Mary Hausbeck, Michigan State University, Department of Plant Pathology, is the Principal Investigator/Project Director and oversaw the entire project objectives, activities and reporting to USDA. She was responsible for research on LDPE and VIF plastic mulches, grafting plants, and extension activities. Dr. Hausbeck was assisted in the design, establishment and maintenance of plots, data collection, statistical analysis and reporting by research assistants Brian Cortright, Stevie Glaspie, Blair Harlan, Sheila Linderman, post-doctoral research associate Dr. Sofia Windstam, and graduate students Jennifer Foster, Leah Granke, and Lina Quesada. A field and lab support crew included undergraduate students Adam Cortright, Halli Gutting, Melissa Mercier, Bob Rector, and labor employees Alex Cook, Jake Gonzales, Tara Oomen, James Romel, Nick Sears, Lorenzo Russey. Grower cooperators contributed in-kind support to Dr. Hausbeck's research by providing pepper plants, squash seeds and labor to the project. Collaborating researchers on this project included Drs. Jianjun Hao, Daniel Brainard, Ronald Goldy, and Barbara Dartt. Dr. Hao, Department of Plant Pathology, with the aid of Drs. Jingfang Ying, Srinivason Durairaj and Donghi Wan, and Elizabeth Kelley and Xiaohong Lu, was responsible for sampling soil for detection of P. capsici and development of real-time PCR protocol for quantifying P. capsici. Dr. Yin with the aid of Dr. Durairaj (postdoctoral researchers) started the project, isolated pathogens, extracted DNAs and designed the technical procedures. Dr. Wan (visiting scholar) worked on technical development of real-time PCR methods, including primer designing and validation, DNA extraction, and developing protocols, establishing standard curves, and studying on the separation of dead cells. After Wan, Elizabeth Kelley (graduate student) continued the work and researched effects of essential oils controlling P. capsici. Xiaohong Lu (graduate student) worked on fungicide resistance of P. capsici. Dr. Brainard, Department of Horticulture, is responsible for the weed assessment component of the research comparing LPDE and VIF plastic mulches and was aided by research assistant D. Corey Noyes and undergraduate students Mary Fledger, Jordan Kozelka, Daryl Lederle, Jeffrey Mann, and Nicholas Parton. Dr. Goldy, Michigan State University Extension, oversaw the Southwest Irrigation Network demonstrating water/soil moisture effects on disease and aided in extension efforts. Dr. Dartt, Lookout Ridge Consulting, was responsible for the economic assessment of the feasibility of the methyl bromide alternatives and techniques being investigated in this project. TARGET AUDIENCES: Twelve presentations targeted 6 scientific audiences and 6 extension audiences which included researchers, extension personnel, industry leaders and stakeholders (growers, packers, processors). The international meeting was the Ontario Fruit and Vegetable Conference, St. Catherines, Ontario, Canada in 2008. National meetings included the Annual Meeting of the American Phytopathology Society, Charlotte, NC (2010), Portland, OR (2009) and Minneapolis, MN (2008); and 19th International Pepper Conference, Atlantic City, NJ. Regional meetings were the Mid-Atlantic Fruit and Vegetable Convention, Hershey, PA; Empire State Fruit and Vegetable Expo, Syracuse, NY; and Great Lakes Fruit, Vegetable and Farm Market Expo, Grand Rapids, MI. Research was presented at a local Wilbur-Ellis Meeting, East Lansing, MI. Demonstration plots (objective 1) were established annually in commercial growers' fields. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Many of the registered fumigant alternatives are effective in controlling Phytophthora but lack the versatility of methyl bromide. The trials on pepper and squash both resulted in plant stunting and vigor loss when using the higher rate of metam potassium under LDPE under Michigan spring conditions. If used on a commercial basis, this treatment program of metam potassium would result in significant yield reductions. Both rates of iodomethane were just as effective as methyl bromide on both crops in the study but more costly when used with reduced rates and VIF film, and twice the cost of methyl bromide when used under LDPE. The use of chloropicrin/dichloropropene can result in reduced vigor and plant growth when used in cool soils. The Paladin product was just as effective as the full rate of methyl bromide, but the odor released by the product can be offensive to workers and surrounding neighbors. Death of weed seeds buried in nylon bags at the first site was influenced by fumigant, plastic mulch type, and weed species. Seed packets fumigated with methyl bromide or chloropicrin/dichloropropene had lower weed emergence than untreated controls. Chloropicrin/dichloropropene provided equivalent or better suppression than methyl bromide and suppressed all species tested by 90% or more. Fumigation with iodomethane under LDPE was ineffective at killing weed seeds. VIF improved the effectiveness of iodomethane and chloropicrin/dichloropropene, but had no detectable effect on the effectiveness of methyl bromide. When applied through drip irrigation every 10 days, a new fungicide from DuPont provided excellent control of P. capsici on peppers. This product was also very effective as a drench treatment on yellow squash for P. capsici control. The registered fungicide products Presidio and Revus were effective on P. capsici as a drip application for peppers and as a drench application for yellow squash. Presidio recently has been labeled for drip-applied treatments on both peppers and squash crops. The quantitative method to detect the population of P. capsici is a fast, precise, and practical technique that can be used in the laboratory, diagnostic service, and soil health measurement. As the application of PCR technology increases, the developed protocol will be affordable for most of the end users. There are two highlighted aspects in this project: efficient soil DNA extraction and accurate estimation of P. capsici population. A protocol of DNA extraction from soil has been optimized to overcome inhibitors and improve the extraction efficiency. Phytophthora capsici in soil can be detected at a population level as low as 18 zoospores/g soil. A critical technique has been implemented for separating dead cells from living P. capsici. This can greatly improve the accuracy and efficiency using this method, which is a contribution to plant pathogen quantification. The reports from the Southwest Irrigation Network demonstrated to growers how their irrigation practices influenced soil moisture and that they could adjust these practices according to how soil moisture was changing in the plantings.
Publications
- Foster, J.M., and Hausbeck, M.K. 2010. Managing Phytophthora capsici in bell pepper using fungicides and host resistance. Plant Disease 94:697-702.
- Foster, J.M., and Hausbeck, M.K. 2010. Resistance of pepper to Phytophthora crown, root, and fruit rot is affected by isolate virulence. Plant Disease 94:24-30.
- Foster, J.M. 2009. Management tools to control Phytophthora capsici in pepper and eggplant. M.S. Thesis, Michigan State University, East Lansing.
- Foster, J.M., and Hausbeck, M. 2010. Phytophthora research and control in peppers. Michigan State University Vegetable Crop Advisory Team Alert Vol 25:(Aug 25). Online.
- Foster, J., and Hausbeck, M. 2009. Phytophthora research and control in peppers. Michigan State University Vegetable Crop Advisory Team Alert Vol. 24(16): (Aug 19). Online.
- Foster, J.M., and Hausbeck, M.K. 2009. Evaluation of fungicides for control of Phytophthora blight of yellow squash in fumigated beds, 2007. PDMR 3:V086.
- Foster, J.M., and Hausbeck, M.K. 2009. Variety selection and fungicide programs for controlling Phytophthora in pepper. Pages 187-189 in: Proceedings of the 2009 Empire State Fruit and Vegetable Expo, Syracuse NY, Feb 11-12.
- Foster, J.M., and Hausbeck, M.K. 2008. Phytophthora research and control in peppers. Great Lakes Fruit, Vegetable and Farm Market Expo, Tomato and Pepper Session Summaries, pp. 2-5. Online.
- Foster, J.M., and Hausbeck, M.K. 2008. Evaluation of bell pepper cultivars and experimental lines for tolerance to Phytophthora crown and root rot, 2007. PDMR 2:V171.
- Hausbeck, M.K., and Cortright, B.D. 2007. Evaluation of fungicides and applications for management of Phytophthora blight of pepper, 2006. PDMR 1:V139.
- Hausbeck, M., Enzenbacher, T., Cortright, B., and Linderman, S. 2010. Phytophthora, films and fumigants. Michigan State University Vegetable Crop Advisory Alert 25:(Sep 8). Online.
- Hausbeck, M., Foster, J., and Linderman, S. 2010. Managing Phytophthora on winter squash. Michigan State University Vegetable Crop Advisory Alert 25:(Sep 8). Online.
- Hausbeck, M., Foster, J., and Linderman, S. 2010. Managing Phytophthora on pepper. Michigan State University Vegetable Crop Advisory Team Alert Vol 25:(1). Online.
- Hausbeck, M.K., and Glaspie, S.L. 2010. Evaluation of fumigants for control of Phytophthora crown, fruit, and root rot of summer squash, 2009. PDMR 4:V055.
- Kelley, E., and Hao, J. 2010. Effect essential oils on inhibition of Phytophthora capsici in vitro. Abstract. Phytopathology 100:S60.
- Lu, X.H., Hao, J.J., and Liu, X.L. 2009. Competitive ability of iprovalicarb-resistant and -sensitive isolates of Phytophthora capsici. in: 2nd International Phytophthora capsici Conference APS, Duck Key, FL.
- Lu, X.H., Liu, X.L., and Hao, J.J. 2010. Competitive ability of iprovalicarb-resistant mutants of Phytophthora capsici. Abstract. Phytopathology 100:S74.
- Lu, X., Zhu, S., Bi, Y., Hao, J., and Liu, X. 2009. Characterization of spontaneous mutants of Phytophthora capsici resistant to iprovalicarb. Abstract. Phytopathology 99(6):S77.
- Cortright, B., and Hausbeck, M. 2010. What's new in fumigation. Great Lakes Fruit, Vegetable and Farm Market Expo, Plasticulture Session Summaries. Online.
- Foster, J.M., and Hausbeck, M.K. 2010. Evaluation of fungicide drenches and resistant cultivars for control of Phytophthora crown rot of pepper, 2009. PDMR 4:V116.
- Foster, J.M., and Hausbeck, M.K. 2010. Evaluation of fungicides and resistant cultivars for control of Phytophthora crown rot of bell pepper, 2008, trial 2. PDMR 4:V119.
- Foster, J.M., and Hausbeck, M.K. 2010. Evaluation of fungicides and resistant cultivars for control of Phytophthora crown rot of bell pepper, 2008, trial 1. PDMR 4:V118.
- Lu, X.H., Zhu, S.S., Bi,Y., Liu, X.L., and Hao, J.J. 2010. Baseline sensitivity and resistance-risk assessment of Phytophthora capsici to iprovalicarb. Phytopathology (in press).
- Qinxiao, M., Xiaolan, C., Yang, B., Xiaohong, L., Hao, J., and Xili, L. 2008. Study on the resistance risk and resistance inheritance of Phytophthora capsici to flumorph. Abstract. Phytopathology 98(6):S128.
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Progress 09/01/08 to 08/31/09
Outputs
OUTPUTS: Michigan researchers established experiments for management of Phytophthora root and crown rot and common weed control on squash and pepper (1 site for each crop) in large-scale replicated demonstration field trials in grower-cooperators' fields. Each experiment was conducted in a field with a known history of disease and weed pressure. Studies compared reduced rates of registered fumigants, including methyl bromide/chloropicrin, metam potassium, chloropicrin dichloropropene, and iodomethane, applied under virtually impermeable film (VIF) versus full fumigant rates under low density polyethylene (LDPE). Fumigant weed-control studies monitored the mortality of weed seeds exposed to the listed treatments at both trial sites. An additional study compared the efficacy of the unregistered dimethyl disulfide/chloropicrin with methyl bromide/chloropicrin for the control of Phytophthora on yellow squash. The effects of fumigants applied under LDPE and VIF mulches on weeds were assessed at two sites by (i) assessing changes in the viability of buried weed seeds, and (ii) evaluating the density of native weeds emerging from planting holes or breaking through plastic. Work continued on developing a protocol using real-time polymerase chain reaction (PCR) to improve the method of P. capsici detection and quantification in soil. The method of real-time PCR involves extracting DNA from sampled soil with a commercial DNA extract kit, and running PCR with pre-designed primers. A set of primers were designed based on the internal transcribed spacer region of the ribosomal DNA that is unique for P. capsici. To separate dead cells, EMA bromide was added, a chemical that can penetrate into dead cells, and bind the DNA of dead cells to form a polymer that can be filtered out by centrifugation. The method is specific to P. capsici and was tested on five P. capsici isolates and samples of 14 other Phytophthora spp. and Pythium sp. The method was tested across three types of soils (sandy loam, clay, muck soil) that were inoculated with same amount of P. capsici zoospores. Five Michigan growers signed up for the irrigation monitoring service offered by the Southwest Irrigation Network in 2009. Crops monitored included cucumber (3 sites), eggplant (1 site), hard squash (2 sites), pepper (7 sites), tomato (3 sites) and yellow squash/zucchini (2 sites). Soil moisture was monitored weekly during the growing season. Plant stage and weather data was entered into the scheduling program and results indicating length of irrigation times for their crops faxed to each grower along with the current soil moisture information. Information on this research has been posted to the website http//plantpathology.msu.edu/labs/Hausbeck/MBTPhytophthora/MBT-Phytop thora-home.htm. Grant objectives were discussed with grower input at the SW Michigan Vegetable Advisory Meeting held in Dec 2009. PARTICIPANTS: Dr. Mary Hausbeck, Michigan State University (MSU), Department of Plant Pathology, is the Principal Investigator/Project Director and oversees the entire project objectives, activities and reporting to USDA. She is responsible for research on LDPE and VIF plastic mulches, methyl bromide studies with unregistered and registered fumigants on eggplant and melon, and extension activities. Dr. Hausbeck was assisted in the design, establishment and maintenance of plots, data collection, statistical analysis and reporting by research assistants Brian Cortright, Blair Harlan, Sheila Linderman. A field and lab support crew included undergraduate students (Adam Cortright, Halli Gutting, Mellissa Mercier) and labor employees (Alex Cook, James Romel, Nick Sears, Lorenzo Russey). Collaborating researchers on this project include Drs. Jianjun Hao, MSU Department of Plant Pathology, Daniel Brainard, MSU Department of Horticulture, and Ronald Goldy, MSU Extension. Dr. J. Hao supervised his group for research of real-time PCR technques. Dr. Jingfang Yin (postdoctoral researcher) started the project, designed some primers, and collected partial cultures. Dongshi Wan (visiting scholar) conducted the project, including primer validation, developing protocols, establishing standard curves, and studying on the separation of dead cells. After Wan, Elizabeth Kelley (graduate student) continued the work and did some adjustments in the later stage of the project. Dr. D. Brainard is responsible for the weed assessment component of the research comparing LPDE and VIF plastic mulches and was aided by research assistant D. Corey Noyes and undergraduate student Jordan Kozelka. Dr. R. Goldy oversaw the Southwest Irrigation Network demonstrating water/soil moisture effects on disease and aided in extension efforts. TARGET AUDIENCES: Demonstration plots were established in commercial growers' fields and targeted growers and industry stakeholders. These plots included pepper and squash studies involving registered and unregistered fumigants and VIF/LDPE films. The PCR soil-assay technique was developed using soil from commercial fields in Michigan. Weed control studies were partnered with the fumigant trials on commercial farms. The irrigation monitoring was conducted with commercial growers and increased their knowledge on proper crop watering. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Many of the registered fumigant alternatives are effective in controlling Phytophthora but lack the versatility of methyl bromide. The trials on pepper and squash both resulted in plant stunting and vigor loss when using the higher rate of metam potassium under LDPE under Michigan spring conditions. If used on a commercial basis, this treatment program of metam potassium would result in significant yield reductions. Both rates of iodomethane were just as effective as methyl bromide on both crops in the study but more costly when used with reduced rates and VIF film, and twice the cost of methyl bromide when used under LDPE. The use of chloropicrin/dichloropropene can result in reduced vigor and plant growth when used in cool soils. The unregistered dimethyl disulfide/chloropicrin product was just as effective as the full rate of methyl bromide, but the odor released by the product can be offensive to workers and surrounding neighbors. Death of weed seeds buried in nylon bags at the first site was influenced by fumigant, plastic mulch type, and weed species. Seed packets fumigated with methyl bromide or chloropicrin/dichloropropene had lower weed emergence than untreated controls. Chloropicrin/dichloropropene provided equivalent or better suppression than methyl bromide and suppressed all species tested by 90% or more. Fumigation with iodomethane under LDPE was ineffective at killing weed seeds. VIF improved the effectiveness of iodomethane and chloropicrin/dichloropropene, but had no detectable effect on the effectiveness of methyl bromide. A real-time PCR protocol for P. capsici would allow growers to know whether the pathogen exists in a field and if it is over the threshold needed for infection to occur. This protocol enables people to quantify the pathogen with high accuracy and sensitivity, and results of P. capsici evaluation can be derived in the same day when samples are delivered. It can be used to evaluate the pathogen population when different disease control methods are applied. For soil assessment using PCR to detect Phytophthora spp., detection of all the P. capsici isolates were positive, while none of the other species (non-P. capsici) was amplified. Low populations of P. capsici can be detected, and the lowest detectable DNA amount was 18 zoospores. The PCR technique was applied to sandy loam, clay, and muck soil and detection was not affected by the soil type. When the soils were mixed with a standard volume (amount) of zoospores with varying ratios of living to dead zoospores, the quantity of zoospores detected remained the same. However, when the infested soil was treated with EMA, the quantity detected varied between samples based on the ratio of live to dead zoospores in a linear manner; soils containing a higher ratio of living zoospores had a higher amount detected, and soils containing a lower ratio of living zoospores had a lesser amount detected. The reports from the Southwest Irrigation Network demonstrated to growers how their irrigation practices influenced soil moisture and that they could adjust these practices according to how soil moisture was changing in the plantings.
Publications
- Foster, J.M., and Hausbeck, M.K. 2009. Evaluation of fungicides for control of Phytophthora blight of yellow squash in fumigated beds, 2007. Plant Disease Management Reports 3:V086. Online.
- Foster, J.M., and Hausbeck, M.K. 2009. Evaluation of fungicides for control of Phytophthora blight of yellow squash grown on flat plant beds, 2007. Plant Disease Management Reports 3:V085. Online.
- Foster, J.M., and Hausbeck, M.K. 2009. Evaluation of fungicides for control of Phytophthora blight of yellow squash grown on raised plant beds, 2007. Plant Disease Management Reports 3:V084. Online.
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Progress 09/01/07 to 08/31/08
Outputs
OUTPUTS: OBJECTIVE 1. Low density polyethylene (LDPE) and virtually impermeable film (VIF) plastic mulches. Large-scale field trials on commercial farms tested reduced rates of fumigants applied under LDPE and VIF on (A) pepper, and (B) yellow squash. Treatments were 300 lb Methyl Bromide/Chloropicrin, 20 gal Telone C35, 175 lb Midas, 30 gal Sectagon K54 + 20 gal Chloropicrin. Each mulch treatment was paired with an untreated. Stand counts and yield were analyzed. Germinable weed seed bank was estimated from pre- and postfumigation soil samples spread over potting mix in the greenhouse; emerging weeds were counted and identified for 2 months. Fumigation and mulch effects were also evaluated on 5 weed spp. by burying mesh bags of soil + 50 seeds of each in each plot. Bags were retrieved 12 days postfumigation and seed germinability evaluated as above. Weed spp. >6 inches tall in the mulch planting holes were evaluated preharvest. Phytophthora samples (35 isolates of 14 species) from the research plot were tested for pathogenicity and identified by conventional polymerase chain reaction (PCR). A protocol of DNA extraction from soil was established. ITS regions of P. capsici were sequenced and analyzed using BLAST in NCBI gene bank. A set of P. capsici-specific primers were designed for real-time PCR with Primer Expression software. EMA bromide (phenanthridium, 3-amino-8-azido-5-ethyl-6-phenyl bromide) was applied to 3 types of soil samples to separate living from dead cells. A standard curve was constructed by using known concentrations of P.capsici mycelium DNA against the Ct value obtained from real-time PCR. Sandy, clay, muck soils were used. OBJECTIVE 2. Grafted plants. Greenhouse evaluation of potential eggplant and pepper rootstocks/scions documented their susceptibility to P. capsici. One day posttransplant, 1 g of Phytophthora-infested millet was inserted 3 cm below the medium surface directly beside the plant plug. Plant wilting, death and area under the disease progress curve were analyzed. (A) Resistant (SCM334), tolerant (Paladin) and susceptible (Red Knight, Camelot) peppers and resistant (EG203, EG195) eggplants were inoculated with 4 isolates of P. capsici (12889, OP97, SP98 and SFF3). (B) Resistant (EG203, EG195) and susceptible (Classic) eggplants and Red Knight pepper were inoculated with 11 isolates of P. capsici (12889, 10 eggplant isolates from NY). (C) Susceptible peppers (Camelot, Red Knight) were grafted onto resistant eggplant (EG203 and EG195) and pepper (SCM334) root stocks. Rootstocks were seeded one week prior to the scions. After 4 weeks, plants were severed at a 45 degree angle (rootstocks above and scions below the cotyledon) and the graft joint united with a grafting clip (tube grafting). Plants were placed into a high humidity chamber for 7 days, and acclimated for 7 days in the greenhouse. OBJECTIVE 4. Extension efforts. A website for this project can be found at http://plantpathology.msu.edu/labs/hausbeck/MBTPhytophthora/MBT-Phyto phthora-home.htm. Dr. Hausbeck met with Michigan growers in Jan 2008 to discuss the upcoming field research. PARTICIPANTS: Dr. Mary Hausbeck, Michigan State University, Department of Plant Pathology, is the Principal Investigator/Project Director and oversees the entire project objectives, activities and reporting to USDA. She is responsible for research on LDPE and VIF plastic mulches, grafting plants, and extension activities. Dr. Hausbeck was assisted in the design, establishment and maintenance of plots, data collection, statistical analysis and reporting by research assistants Brian Cortright, Stevie Glaspie, Blair Harlan, Sheila Linderman, post-doctoral research associate Dr. Sofia Windstam, and graduate students Jennifer Foster, Leah Granke, Lina Quesada. A field and lab support crew included undergraduate students Halli Gutting, Melissa Mercier, Bob Rector, and labor employees Alex Cook, Jake Gonzales, Tara Oomen. Grower cooperators contributed in-kind support to Dr. Hausbeck's research by providing pepper plants, squash seeds and labor to the project. Collaborating researchers on this project include Drs. Jianjun Hao, Daniel Brainard, Ronald Goldy, and Barbara Dartt. Dr. J. Hao, Department of Plant Pathology, with the aid of Drs. Jingfang Ying, Srinivason Durairaj and Donghi Wan, is responsible for sampling soil for detection of P. capsici and development of real-time PCR protocol for quantifying P. capsici. Dr. D. Brainard, Department of Horticulture, is responsible for the weed assessment component of the research comparing LPDE and VIF plastic mulches and was aided by undergraduate student Nicholas Parton. Dr. R. Goldy, Michigan State University Extension, is overseeing demonstrating water/soil moisture effects on disease and aiding in extension efforts. Dr. B. Dartt, Salisbury Management Services is responsible for the economic assessment of the feasibility of the methyl bromide alternatives and techniques being investigated in this project. TARGET AUDIENCES: The growers meeting in Jan 2008 was attended by Dr. M. Hausbeck, her research assistant B. Cortright, Dr. R. Goldy, and 7 Michigan growers. The EPA Decision Makers Tour featured the pepper and yellow squash plots and presented fumigation trial data on 30 Jul to government officials, growers, and industry stakeholders. Data on the resistance of commercial and breeding lines of bell peppers to P. capsici was presented at the 19th International Pepper Conference, Sep 7-10, Atlantic City, NJ and was attended by research scientists, industry stakeholders, growers and extension personnel. The website dedicated to this project (http://plantpathology.msu.edu/labs/hausbeck/MBTPhytophthora/MBT-Phyt ophthora-home.htm) is targeted to growers, industry stakeholders and extension personnel. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
OBJECTIVE 1. (A) Disease pressure in the pepper fumigant trial never developed enough to accurately assess treatment differences. Sectagon K54 treatments (LDPE, VIF) had significantly fewer dead plants than their paired untreated. Yields were not assessed as disease was so low over the large blocks. (B) Large variations in paired untreated control infections occurred in the yellow squash fumigant plot due to uneven P. capsici infestation. VIF tended to have less disease than corresponding LDPE treatments. Only VIF-Telone C35 and VIF-LDPE-Sectagon K54 + Chloropicrin had lower plant death than their paired controls on 11 Jul and 11 Aug. Germinable weed seed density from prefumigated soil averaged 160/sq m (squash: large crabgrass, marsh yellow-cress, lady's-thumb, carpetweed, purslane) and >2000/sq m (pepper: large crabgrass, lambsquarters, Powell amaranth, marsh yellow-cress, carpetweed). Postfumigated squash field soil had no germinable seeds in the Methyl Bromide/Chloropicrin or Midas plots, but VIF-Telone had marsh yellow-cress and purslane. There were few statistical differences among treatments for weeds in pepper postfumigated soil samples; however, VIF tended to improve weed suppression, particularly for Methyl Bromide/Chloropicrin and Telone C35. Death of weed seeds buried in nylon bags in the squash field was strongly influenced by fumigant, mulch type, and weed spp. No weeds emerged from soils fumigated under VIF. Weed emergence from unfumigated squash controls ranged from 0 (yellow nutsedge) to 29% (large crabgrass). Weed suppression in squash mulch holes was 100% for all VIF plots; LDPE-Midas did not suppress crabgrass, carpetweed or marsh yellowcress, and LDPE-Telone did not suppress carpetweed. Phytophthora DNA in soil samples was detected as low as 1x10E-5 ng, corresponding to 18 zoospores. This method allowed differentiation of living from dead cells, although the technique needs further modification. P. capsici was amplified with real-time PCR from all 3 soil types after infesting with zoospores (untreated or treated with EMA). OBJECTIVE 2. (A) Resistant pepper SCM334 did not show disease. All susceptible Red Knight and Camelot died, and 63% of tolerant Paladin died when inoculated with 12889. When inoculated with OP97, SP98 or SFF3, <37% of Red Knight and Camelot died, while none of Paladin wilted or died. (B) Preliminary results from the eggplant trial show that EG203 and EG195 are healthy while Classic plants are wilting and dying. (C) Camelot was the only scion successfully grafted onto eggplant rootstocks; however, plants were fragile and did not survive acclimatization. OBJECTIVE 4. Dr. Hausbeck presented 2007 results at the growers meeting in Jan 2008, discussed growers concerns and planned 2008 research. 'Vegetable Phytophthora capsici and fumigant trials' were featured on the EPA Tour on 30 Jul. 'Evaluating commercial and breeding lines of bell peppers for resistance to Phytophthora root, crown and fruit rot,' was presented at the 19th International Pepper Conference, 7-10 Sep in Atlantic City, NJ.
Publications
- Foster, J., and Hausbeck, M. 2008. Evaluating commercial and breeding lines of bell peppers for resistance to Phytophthora root, crown and fruit rot. Page 32 in: Proceedings of the 19th International Pepper Conference, Sep 7-10, Atlantic City, NJ.
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