Source: CORNELL UNIVERSITY submitted to NRP
COMBATING NEW DISEASES OF ORNAMENTALS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
1007210
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Oct 1, 2015
Project End Date
Sep 30, 2018
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
CORNELL UNIVERSITY
(N/A)
ITHACA,NY 14853
Performing Department
Plant Pathology
Non Technical Summary
For ornamental crops, plants can be rendered unsaleable because of a reduction in plant size, an uneven shape, a delay in flowering, or leaf spots or blight. The pressure is great for a greenhouse or nursery grower of ornamentals to produce vibrant, healthy plants without flaws. Diseases known for over a century are still problematic, butincreased globalization of trade has also aharply increased the number of new diseases that appear annually in ornamentals. In the past 6 years, five major crops, boxwood, callery pear, Japanese maple, calibrachoa and impatiens, have been troubled by new diseases that have already had immense financial impact on the nursery and greenhouse industries. Boxwood is threatened by a fungus disease called boxwood blight, not known anywhere on the globe until the mid-1990s when it appeared in the UK, which causes leaf spots and defoliation of valuable landscape specimens. Callery pear foliage in the eastern US is now threatened by the pear trellis rust that alternates between pears and junipers. Japanese maple in the USrecently has developed a new powdery mildew problem caused by the fungus Sawadaea polyfida.Impatiens walleriana, the number one bedding plant in the United States, has lost popularity in Florida and the Northeast precipitously in the past few years due to a downy mildew disease that defoliates and kills. Meanwhile, greenhouse flower crops (including geranium, poinsettias, andthe petunia relative, calibrachoa)continue to experience problems with root diseases caused by water molds that can kill or stunt plants and destroy their value. All ofthese problems need new solutions to reduce the need for protective chemical applications. Our studies attempt to ameliorate these formidable new problems by a series of investigations.We will establish a field plot to lookfor genetic resistance to boxwood blightin plant material fromboxwood collections at the US National Arboretum and Longwood Gardens, and will also test biological controls for their ability to protect boxwood against this new disease. Studies with pears and junipers will evaluate different fungicides and biological controls for their ability to stop infection. We will survey nurseries looking for Japanese maples with a natural resistance to the new powdery mildew problem, and will test different management programs to curb this disease during the growing season. A graduate student working on his PhD degree at Cornell University has produced some hybrid impatiens that we will compare with other hybrids, cultivars and species to see which plants have the lowest susceptibility to impatiens downy mildew. We will also observe downy mildew infection of a native impatiens species called jewelweed, to see how its susceptibility variesfrom that of the common bedding plant, and we'll do experiments with balsam impatiens to see if its seed would be able to carry the disease over from one year to the next in the garden. We will do trials with a potential new root rot disease in calibrachoa, looking to see if a new species of water mold is able to cause problems in this crop that is such a mainstay of decorative hanging baskets. We will also test a rhamnolipid, a natural wetting agent produced by some species of bacteria, to see if it can help to prevent water molds from causing root rot on geraniums and poinsettias. By focusing on each of these serious plant problems, we hope to learn new information that will help growers and landscapers to produce and maintain healthy ornamentals that will be an asset to the environment.
Animal Health Component
100%
Research Effort Categories
Basic
(N/A)
Applied
100%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
21221991160100%
Knowledge Area
212 - Pathogens and Nematodes Affecting Plants;

Subject Of Investigation
2199 - Ornamentals and turf, general/other;

Field Of Science
1160 - Pathology;
Goals / Objectives
The overall goal of this project is to discover information that willreducelosses caused by new diseases of ornamentals during production or landscape use,with minimized use of pesticides. We aim to identifyalternatives to chemical control forthe new boxwood blight and impatiens downy mildew, develop management options for pear trellis rust onornamental pear,powdery mildew on Japanese maple, and Phytophthora and/or Pythium root rot oncalibrachoa, geranium and poinsettiaand also toexplore the use of rhamnolipids for root rot management. Objectives:1. Identify resistant cultivars forboxwood blight 2. Test biological control agents against boxwood blight2. Find effective biological and chemical controls for pear trellis rust in callery pear and in its alternate host,juniper3. Survey nurseries for presence of powdery mildew on Japanese maple. 4.Test biopesticides and fungicides for management ofpowdery mildew on Japanese maple. 4. Find Impatiens species or hybrids with less susceptibility to impatiens downy mildew 5. Investigatethe role of the balsam impatiens and jewelweed as inoculum sources for downy mildew on Impatiens walleriana. 6. Determine whether Phytophthora cactorum is a pathogen of calibrachoa and evaluate control measures7. Assess benefit ofrhamnolipids as drenches to prevent Pythium root rot on potted geraniums and poinsettias.
Project Methods
1. We will establish 50boxwood accessions from the US National Arboretum and Longwood Gardensin afield trial in a trickle-irrigatedpot-in-pot production area at the LIHREC with5 replications of each type,to observe their susceptibility to natural infection by Calonectria pseudonaviculata, the fungus causing the new boxwood blight. Plants will be rated for incidence of both insect and disease symptoms and signs over a three year period. 2. Cuttings of boxwood (new growth in a spring trial and mature growth in a fall trial) will be sprayed withsolutions of commercially available biocontrols containing various Trichoderma and Bacillus species as active ingredients, to compare disease suppression in contrast to chlorothalonil treatment after treated and non-treated control plants are inoculated with C. pseudonaviculata. Leaf spots, stem cankers and leaf drop will be recorded and compared.3. A field trial will be conducted on the susceptible'Cleveland Select' callery pear to evaluate fungicides from 3 mode of action groups as well as 2 biofungicides for ability to protect trees in the spring from a juniper inoculum source of pear trellis rust. 4. A field trial will also be conducted on a juniper alternate host for the pear trellis rust, by exposing treated junipers to inoculum from pear in the fall and then evaluating rust sporulation incidence the following spring.5. Three Long Island nurseries will be visited each year during summer or fallto observe and record development of powdery mildew on different Japanese maple cultivars with the hope of identifyingcultivars with low susceptibility. 6. A replicated trial will be conducted on Acer palmatum to evaluate phytotoxicity and effectiveness of one organic and one chemical control program for powdery mildew management during a growing season7.A susceptibility comparison trial will be established in containers grown in a shaded hoop house with overhead irrigation, to compare Cornell-developed impatiens hybrids and other available contenders to the very susceptible Impatiens walleriana 'SuperElfin White'. Plants will be rated for downy mildew sporulation incidence and severity.8. Balsam impatiens seed obtained commercially will be sown at the same time asseed obtained from downy mildew-infected plants in plastic bags in a growth chamber, and external and internal signs of downy mildew will be observed as the plants grow and develop within the bags. 9. Aninfection trial will be performedon the native Impatiens capensis using downy mildew inoculumfrom I. walleriana, using microscopic observation to observe any differences in the interaction of the pathogen with these two hosts. 10. A proof-of-pathogenicity trial will be conducted in the greenhousewith Phytophthora cactorum and other Phytophthora species to establish whether P. cactorum is a cause of crown rot of calibrachoa. 11. Various drench rates of the rhamnolipid product Zonix will be tested in different soilless growing media for safety and effectiveness on geraniums and poinsettias against Pythium root rot in two inoculated trials. Two-week old potato-dextrose agarcultures of Pythium aphanidermatum will be cut with a 6-mm cork borer, and the resulting discs of mycelium will be used as a point-source of inoculum within each pot. Disease symptoms (wilt) will be recorded over time, and plants will be harvested at the soil line for dry weight determination at the end of the trials.

Progress 10/01/15 to 09/30/18

Outputs
Target Audience:Nursery producers of boxwood on the East Coast of the US and in Belgium; arborists, parks personnel, landscape gardeners, extension educators, Master Gardeners and herb society members concerned with boxwood blight mitigation, rust on callery pear and powdery mildew on Japanese maple; greenhouse growers of impatiens and calibrachoa in the US as well as landscape gardeners, state horticultural inspectors in NY and VA; other scientists, including diagnosticians. Changes/Problems:Some of the objectives were not attained, which was probably largely due to having too many objectives in this project. The importance of boxwood blight and impatiens downy mildew to the nursery and greenhouse industries, respectively, made them overshadow other topics, which are still deserving of research attention. Efforts to understand more about the control of powdery mildew on Japanese maple and pear trellis rust will continue in my research program; studies on Phytophthora diseases will likely focus on lavender, as this increasingly popular crop has shown the most problem with Phytophthora infections in the past several years. What opportunities for training and professional development has the project provided?Training of Dr. Mark Bridgen's Dept. of Plant Breeding graduate student was made possible by this project: because of our shared goal, the student was in a position to learn a great deal about plant pathology, particularly how downy mildews interact with plants. The boxwood blight component of the project allowed professional development activities for the PI as well, including participation (presentation as well as learning) at the Boxwood and Beyond conference in Beltsville in February 2018, and at a Boxwood Blight Workshop held at the International Congress of Plant Pathology held in Boston in August, 2018. How have the results been disseminated to communities of interest?There have been numerous opportunities for dissemination of findings to communities of interest on national, international and local levels: for boxwood blight, information was shared with growers, landscape gardeners, state departments of agriculture and other scientists at the American Boxwood Association's symposium at Beltsville, MD in Feb 2018, as well as at the International Congress of Plant Pathology in Boston in August, 2018 with plant pathologists from the US as well as the Czech Republic and the UK, plus at the Long Island Horticulture Conference in 2018 and at meetings of the LI Herb Society, Pest Control Applicators of Long Island, LI Arborists and Nassau-Suffolk Landscape Gardeners Association and the Kanuga Ornamentals Workshop in NC in October 2018. Information on impatiens downy mildew has been presented at the national Cultivate conference in Columbus, OH in 2017 as well as to the LI Greenhouse and Floriculture Conference and the Kanuga Ornamentals Workshop in 2016. Control guidance on pear trellis rust was given in a presentation to the Long Island Arborists in 2017 and also to the Hudson Valley Greenhouse and Nursery Conference. Knowledge of the powdery mildew on Japanese maple has been shared in Westchester, Nassau and Suffolk Counties at Master Gardener trainings and at extension conferences. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Alternatives to chemical sprays were identified for the impatiens downy mildew caused by Plasmopara obducens. Both Dr. Mark Bridgen's interspecific hybrids from his Cornell plant breeding program and commercial lines produced by Syngenta as the Imara XDR series have been trialed under heavy disease pressure in field and greenhouse areas at the Long Island Horticultural Research & Extension Center. The plants have held up well under environmental conditions very conducive to downy mildew disease. Starting with the introduction of Imara XDR impatiens this spring, growers will have an alternative seed-grown impatiens that is resistant to at least one strain of downy mildew present in the Northeastern US, and European trials have also shown good results. Balsam impatiens show very high susceptibility to P. obducens and can serve as a landscape reservoir that will allow new epidemics to arise each spring when weather is sufficiently rainy. Boxwood with lower susceptibility to boxwood blight have been developed in Virginia as NewGen boxwood by Saunders Brothers Nursery, which will become available to the trade shortly; we were invited to attend a meeting of boxwood researchers convened by the trade association AmericanHort in March 2008 to discuss how these and other better boxwood coming on the market might be tested uniformly by the scientific community to validate claims of resistance. Until this new generation of boxwood becomes widely available, it will be necessary for us to advise gardeners and nurserymen on what alternative boxwood cultivars to grow in the meantime, based on field and laboratory cultivar comparison research that we and our collaborators in VA, NC, CT and NJ have conducted. The data is now available to guide boxwood users away from the highly susceptible Buxus sempervirens 'Suffruticosa' and other highly susceptible plants such as B. sempervirens 'Justin Brouwers' to cultivars with statistically less disease susceptibility. By consideration of our own observations and the research conducted by collaborators in VA, NC, CT, and NJ, it is now possible to suggest to gardeners and nurserymen which boxwood cultivars will perform better than Buxus sempervirens 'Suffruticosa' and other very highly susceptible plants such as B. sermpervirens 'Justin Brouwers'.

Publications

  • Type: Books Status: Published Year Published: 2018 Citation: Chase AR, Daughtrey ML and Cloyd, RA. 2018. Compendium of Bedding Plant Diseases and Pests, American Phytopathological Society, St. Paul, MN. 170 pp.
  • Type: Other Status: Published Year Published: 2018 Citation: Daughtrey M and Hyatt L. 2018. Powdery mildew management trial with BAS 75002F on zinnia. 2017 Annual Report, Long Island Horticultural Research & Extension Center. Cornell University Bulletin 90:36-37. https://cuaes.cals.cornell.edu/sites/cuaes.cals.cornell.edu/files/shared/documents/2017_LIHREC_Annual%20Report_compressed.pdf
  • Type: Other Status: Published Year Published: 2018 Citation: Daughtrey, M. and Hyatt, L. 2018. Picatina and Picatina Flora fungicides evaluated for the control of Botrytis blight on angelonia. 2017 Annual Report, Long Island Horticultural Research & Extension Center. Cornell University Bulletin 90:37-38.
  • Type: Other Status: Published Year Published: 2018 Citation: Daughtrey, M., Rychlik, P. and Garzon, C. 2018. Pythium population assessment in Long Island greenhouses, 2017. Cornell University Bulletin 90:38. https://cuaes.cals.cornell.edu/sites/cuaes.cals.cornell.edu/files/shared/documents/2017_LIHREC_Annual%20Report_compressed.pdf
  • Type: Other Status: Published Year Published: 2018 Citation: Mattson, N., Daughtrey, M., Catlin, N., McGrath, M., Hyatt, L. and Rychlik, P. 2018. Use of low intensity LED lamps to reduce basil downy mildew in the greenhouse. 2017 Annual Report, Long Island Horticultural Research & Extension Center. Cornell University Bulletin 90:38-39. https://cuaes.cals.cornell.edu/sites/cuaes.cals.cornell.edu/files/shared/documents/2017_LIHREC_Annual%20Report_compressed.pdf
  • Type: Book Chapters Status: Awaiting Publication Year Published: 2019 Citation: Daughtrey, M. and Buitenhuis, R. In press. Chapter 23. Ornamentals In: M. L. Gulllino, R. Albajes, P. Nicot , eds. Integrated Pest and Disease Management in Greenhouse Crops, 2nd ed. Plant Pathology in the 21st Century Series, Springer
  • Type: Book Chapters Status: Submitted Year Published: 2019 Citation: Daughtrey, M. xxxx. Boxwood Blight: Threat to Ornamentals. Annual Review of Phytopathology. Annual Reviews, Palo Alto, CA. Vol. 57:xx.
  • Type: Other Status: Published Year Published: 2018 Citation: Daughtrey, M., Rychlik, P. and Hyatt, L. 2018. Diagnoses of diseases on greenhouse crops and herbaceous perennials in 2017. 2017 Annual Report, Long Island Horticultural Research & Extension Center. Cornell University Bulletin 90:92. https://cuaes.cals.cornell.edu/sites/cuaes.cals.cornell.edu/files/shared/documents/2017_LIHREC_Annual%20Report_compressed.pdf
  • Type: Journal Articles Status: Published Year Published: 2018 Citation: Salgado-Salazar, C., Shishkoff, N., Daughtrey, M., Palmer, C. L. and Crouch, J. A. 2018. Downy mildew: a serious disease threat to rose health worldwide. Plant Disease 102:1873-1882.
  • Type: Other Status: Published Year Published: 2018 Citation: Daughtrey, M. Blight still battering boxwood (Insert). Branching Out: An IPM Newsletter for trees and shrubs. Cornell Cooperative Extension. 25(6).
  • Type: Other Status: Published Year Published: 2018 Citation: Norman, D., Allen, C., and Daughtrey, M. 2018. When roses are blue. Greenhouse Management, March. pp. 38-39. https://www.greenhousemag.com/article/when-roses-are-blue-ralstonia-wilt/
  • Type: Other Status: Published Year Published: 2018 Citation: Garzon, C. and Daughtrey, M. 2018. Whos causing Pythium root rot now? Greenhouse Management, Feb. https://www.greenhousemag.com/article/whos-causing-pythium-root-rot-now/
  • Type: Other Status: Published Year Published: 2018 Citation: Bridgen, M., Daughtrey, M. L. 2018. Breeding for downy mildew resistance in Impatiens walleriana. 2017 Annual Report, Long Island Horticultural Research & Extension Center. Cornell University Bulletin 90:31-32. https://cuaes.cals.cornell.edu/sites/cuaes.cals.cornell.edu/files/shared/documents/2017_LIHREC_Annual%20Report_compressed.pdf
  • Type: Other Status: Published Year Published: 2018 Citation: Daughtrey, M., Catlin, N. and Hyatt, L. 2018. Cultivar trial comparing seed-grown impatiens for their susceptibility to impatiens downy mildew. 2017 Annual Report, Long Island Horticultural Research & Extension Center. Cornell University Bulletin 90:36. https://cuaes.cals.cornell.edu/sites/cuaes.cals.cornell.edu/files/shared/documents/2017_LIHREC_Annual%20Report_compressed.pdf


Progress 10/01/16 to 09/30/17

Outputs
Target Audience:The target audience this period has included greenhouse growers, botanical garden and arboretum staff, nurserymen, arborists, landscape gardeners, Master gardeners, cooperative Extension educators and fellow scientists. Changes/Problems:The calibrachoa Phytophthora work planned will be shifted to a newer, currently relevant Phytophthora disease seen on cyclamen in 2017, because the inoculum is available and there is no information available on this host-pathogen system. Studies on Pseudomonas chlororaphis may replace those planned for Zonix; both will be done if time permits. What opportunities for training and professional development has the project provided?An undergraduate student, Yuqi Chen, working under the supervision of Mark Bridgen in the Cornell University Section of Horticulture, was trained in recognizing and rating infection by Plasmopara obducens, the impatiens downy mildew, while working in field plots in summer 2017. An intern, Emma Wallace, working under the direction of JoAnne Crouch of USDA-ARS, Beltsville, MD, was able to come to Long Island for a two-day tour of locations where new downy mildews might be identified in public landscapes and nurseries. This visit led to several new discoveries and manuscripts that have been submitted for publication. How have the results been disseminated to communities of interest?Information has been disseminated widely though cooperative extension and trade association channels. Venues for presentations included presentations on Pythium and boxwood studies at the annual meeting of the Northeastern Division of the American Phytopathological Society in Quebec City and the annual APS meeting in San Antonio in 2017. Additional communities of interest were addressed on disease research, management and control topics in 2017 at the Mid-Atlantic Fruit and Vegetable Conference in Hershey, PA; the MD-DC-VA Landscape Contractors Association conference in Shady Grove, MD; Chesapeake Green in Linthicum, MD; the annual meeting of the Lilac Society in Boston, MA; the San Diego CAPCA Nursery Greenhouse Seminar in Escondido, CA; AmericanHort's Cultivate in Columbus, OH; Keeping Those Dratted Diseases Out of Your Greenhouse Crops in New Haven, CT; Long Island Agricutural Forum Nursery and Greenhouse Sessions; Long Island Greenhouse and Floriculture Conference; Hudson Valley Nursery and Greenhouse Growers School in Middletown, NY; Long Island Horticulture Conference in Upton, NY; three LI Arboricultural Association Meetings; the 2017 Pesticide Applicator Update at Cornell University, Ithaca, NY; the NY Capital Region Bedding Plant Conference, Voorheesville, NY; the PCA Conference of LI in Hauppauge, NY; the NYSNLA Certified Nurseryman's and Landscaper's Training Program in Holtsville, NY; the Long Island Oak Wilt Symposium in Upton, NY; the Managing Landscapes Sustainably program of CCE Suffolk Co. in Stony Brook, NY; and the NY Greengrass Assn. Conference in Hauppauge, NY. What do you plan to do during the next reporting period to accomplish the goals?The next reporting period should allow a spring chemical control study on pear trellis rust using inoculum from a landscape site identified in 2017, also growth chamber studies on biocontrol of boxwood blight disease using Trichoderma and Bacillus species. Summer trials on impatiens downy mildew will continue, assessing performance of hybrids developed in the Cornell breeding program. Pythium and Phytophthora biocontrol and chemical trials will be conducted in the greenhouse, switching to a study of a new Phytophthora disease on cyclamen discovered in 2017 rather than the calibrachoa disease as originally planned.

Impacts
What was accomplished under these goals? Boxwood cultivars from the US National Arboretum have been maintained in a pot-and-pot field area and evaluated for susceptibility to boxwood blight caused by Calonectria pseudonaviculata, but so far none of these plants have become infected. We have chosen not to inoculate the boxwood because of the closeness of the plot to a commercial nursery producing boxwood, but will evaluate a natural infection should it occur. Boxwood cuttings of cv. Green Mountain grown in the greenhouse are now rooted and available for growth chamber studies to assess the ability of biocontrols organisms to reduce infection incidence. Biocontrol studies in other disease systems have indicated some promising candidates to test. Soil samples were collected from two landscape sites with boxwood blight to evaluate the persistence of inoculum over time. For pear rust control studies, a cooperator was located to assist with obtaining callery pear seedlings. Samples of rust-infected juniper gathered in 2017 will allow identification of new disease hosts for chemical control trials in 2018. Additional Japanese maple types susceptible to powdery mildew were identified during 2017, but the amount of rainfall reduced the signs of this disease. Trials of the common impatiens adjacent to trials of impatiens with significant disease resistance in summer 2017 made it very clear that plants from all of the major seed suppliers to the bedding plant industry are highly susceptible, and that the disease cannot be managed merely by shifting to different cultivars. In spite of the many frequent comments heard from landscapers about the higher susceptibility of white-flowered cultivars, no greater disease susceptibility was seen in white cultivars in our trial.

Publications

  • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Wallace, S., Proano, M. F., Espindola, A., Arif, M., Daughtrey, M. L., Garzon, C. D. 2017. Validation of species-specific primers for detection and discrimination of Pythium aphanidermatum and P. deliense. Annual Meeting, American Phytopathological Society, San Antonio, TX. https://apsnet.confex.com/apsnet/2017/meetingapp.cgi/Paper/5873
  • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Proano, M. F., Ayala, C, Chiriboga, A., Garrido, P., Diaz, E., Marek, S. M., Melouk, H. A., Daughtrey, M. L., and Garzon, C. D. 2017. Temporal and host driven variation of Pythium and Globisporangium populations in chrysanthemum and geranium. Annual Meeting, American Phytopathological Society, San Antonio, TX. https://apsnet.confex.com/apsnet/2017/meetingapp.cgi/Paper/5896
  • Type: Book Chapters Status: Published Year Published: 2017 Citation: Elmer, W. H. and Daughtrey, M. L. 2017. Diseases of Cyclamen. In McGovern, R. J. and Elmer, W. H. (eds.)Handbook of Florist's Crops Diseases, Handbook of Plant Disease Management, DOI 10.1007/978-3-319-32374-9_42-1
  • Type: Book Chapters Status: Published Year Published: 2017 Citation: Daughtrey, M. and Chase, A. 2017. Diseases of Poinsettia. In McGovern, R. J. and Elmer, W. H. (eds.)Handbook of Florist's Crops DIseases, Handbook of Plant Disease Managment, DOI 10.1007/978-3-319-32374-9_39-1
  • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Daughtrey, M., Rychlik, P. and Hyatt, L. 2017. Boxwood blight in the Long Island, NY landscape. Northeastern Division, American Phytopathological Society, Quebec City, Quebec, Canada. https://apsjournals.apsnet.org/doi/pdf/10.1094/PHYTO-107-12-S5.196
  • Type: Other Status: Published Year Published: 2017 Citation: Keach, J., Bridgen, M., and Daughtrey, M. Breeding for downy mildew resistance in Impatiens walleriana, 2016 Annual Report, Long Island Horticultural Research & Extension Center, Cornell Universitp. p. 32. https://cuaes.cals.cornell.edu/sites/cuaes.cals.cornell.edu/files/shared/documents/LIHREC_2016AnnualReport_comp.pdf
  • Type: Other Status: Published Year Published: 2017 Citation: Daughtrey, M. and Hyatt, L. 2017. Management of powdery mildew on pansy with Actinovate and Adorn. 2016 Annual Report, Long Island Horticultural Research & Extension Center, Cornell University, p. 36-37. https://cuaes.cals.cornell.edu/sites/cuaes.cals.cornell.edu/files/shared/documents/LIHREC_2016AnnualReport_comp.pdf
  • Type: Other Status: Published Year Published: 2017 Citation: Daughtrey, M., Hyatt, L., and Rychlik, P. 2017. Chrysanthemum Fusarium wilt management using biological control, 2016 Annual Report, Long Island Horticultural Research & Extension Center, p. 36. https://cuaes.cals.cornell.edu/sites/cuaes.cals.cornell.edu/files/shared/documents/LIHREC_2016AnnualReport_comp.pdf
  • Type: Other Status: Published Year Published: 2017 Citation: Daughtrey, M. and Rychlik, P. 2017. Control of Botrytis on geranium with Howler biofungicide. https://cuaes.cals.cornell.edu/sites/cuaes.cals.cornell.edu/files/shared/documents/LIHREC_2016AnnualReport_comp.pdf
  • Type: Other Status: Published Year Published: 2017 Citation: Daughtrey M. and Hyatt, L. 2017. Management of Botrytis on geranium with an experimental fungicide. 2016 Annual Report, Long Island Horticultural Research & Extension Center, Cornell University, p. 37-38. https://cuaes.cals.cornell.edu/sites/cuaes.cals.cornell.edu/files/shared/documents/LIHREC_2016AnnualReport_comp.pdf
  • Type: Other Status: Published Year Published: 2017 Citation: Daughtrey M. and Hyatt, L. 2017. Management of powdery mildew on petunias with an experimental fungicide. 2016 Annual Report, Long Island Horticultural Research & Extension Center, Cornell University, p. 39. https://cuaes.cals.cornell.edu/sites/cuaes.cals.cornell.edu/files/shared/documents/LIHREC_2016AnnualReport_comp.pdf
  • Type: Other Status: Published Year Published: 2017 Citation: Daughtrey M. and Hyatt, L. 2017. Management of downy mildew on digitalis with Segovis. 2016 Annual Report, Long Island Horticultural Research & Extension Center, Cornell Universit, p. 40. https://cuaes.cals.cornell.edu/sites/cuaes.cals.cornell.edu/files/shared/documents/LIHREC_2016AnnualReport_comp.pdf
  • Type: Other Status: Published Year Published: 2017 Citation: Daughtrey, M. and Rychlik, P. 2017. Management of Thielaviopsis with Picatina and Picatina Flora. 2016 Annual Report, Long Island Horticultural Research & Extension Center, Cornell University, p. 41-42. https://cuaes.cals.cornell.edu/sites/cuaes.cals.cornell.edu/files/shared/documents/LIHREC_2016AnnualReport_comp.pdf
  • Type: Other Status: Published Year Published: 2017 Citation: Daughtrey M. and Hyatt, L. 2017. Management of Pythium aphanidermatum on Geranium with Mural and Plentrix. 2016 Annual Report, Long Island Horticultural Research & Extension Center, Cornell University, p. 42-43. https://cuaes.cals.cornell.edu/sites/cuaes.cals.cornell.edu/files/shared/documents/LIHREC_2016AnnualReport_comp.pdf
  • Type: Other Status: Published Year Published: 2017 Citation: Daughtrey, M. and Hyatt, L. 2017. Use of Orkestra Intrinsic against Sclerotinia on petunias. 2016 Annual Report, Long Island Horticultural Research & Extension Center, Cornell University, p. 40-41. https://cuaes.cals.cornell.edu/sites/cuaes.cals.cornell.edu/files/shared/documents/LIHREC_2016AnnualReport_comp.pdf
  • Type: Other Status: Published Year Published: 2017 Citation: Daughtrey, M., and Rychlik, P. 2017. Studies of Pythium populations in Long Island greenhouses. 2016 Annual Report, Long Island Horticultural Research & Extension Center, Cornell University, p. 41. https://cuaes.cals.cornell.edu/sites/cuaes.cals.cornell.edu/files/shared/documents/LIHREC_2016AnnualReport_comp.pdf


Progress 10/01/15 to 09/30/16

Outputs
Target Audience:Greenhouse growers, botanic gardens employees, horticultural business tradespeople, Master Gardeners, arborists, landscape gardeners, nurserymen, cooperative extension educators, home gardeners and plant pathologists. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Graduate students at Cornell University working on the plant breeding of improved impatiens have been able to work with us on the field trial studies on impatiens downy mildew, learning how to evaluate and quantify disease under conducive environmental conditions in inoculated plots. How have the results been disseminated to communities of interest?Presentations have been given on this NIFA-supported research at multiple venues in 2016, including the Academy of Crop Production at the University of Georgia, Cultivate16 in Columbus, OH sponsored by AmericanHort, the Cornell Floriculture Field Day in Ithaca, the NY State Arborists Annual Meeting, the Long Island Horticultural Research and Extension Center Plant Science Day, the Long Island Agricultural Forum, the Long Island Horticulture Conference, the Long Island Greenhouse and Floriculture Conference, the Hudson Valley Nursery and Greenhosue Conference in Middletown, the Iowa State University Greenhouse Short Course in Ames, the GroPro Plug and Cutting Conference in Carlsbad, CA, The New York State Turf and Landscape meeting in Yonkers, as well as Certified Nursery and Landscape Practitioner and Master Gardener training in southeastern NY. In addition, an extension bulletin facilitating the proper identification of boxwood diseases and insect pests including boxwood blight was written and published in conjunction with Cornell Cooperative Extension of Suffolk County; on-line access was provided and 1000 copies were printed. Research on impatiens downy mildew and boxwood blight was reported to the scientific community at the Northeastern Plant, Pest and Soils Conference in Philadephia, PA. What do you plan to do during the next reporting period to accomplish the goals?Trials will be conducted on overwintering and hybrid impatiens susceptibility to impatiens downy mildew; on the ability of biological control agents to reduce infection by Calonectria pseudonaviculata on boxwood; on the chemical control of pear-trellis rust and on the susceptibility of and calibrachoas to Phytophthora disease--and its control. Surveys will be made in garden centers and nurseries on the powdery mildew on Japanese maples.

Impacts
What was accomplished under these goals? A boxwood cultivar plot in a trickle-irrigated pot-in-pot field nursery area has been established for evaluation of relative susceptibility of plants to boxwood blight caused by Calonectria pseudonaviculata. The disease will not be inoculated into the plot; natural infection with pathogens and pests of boxwood is being evaluated annually. Boxwood have been propagated for future biocontrol studies with Trichoderma and Bacillus species. A source of callery pear for management studies in spring 2017 has been found. Twenty-three Impatiens species and hybrids were screened for their resistance to downy mildew caused by Plasmopara obducens in 2015, and evaluations will continue into 2017. Results include the finding of 7 new hosts for downy mildew casued by P. obducens (I. briartii, I. cinnabarina, I. grandis, I. irvingii, I. laurentii, I. repens and I. sodenii), and the verification that a hybrid of two impatiens produced by plant breeders at Cornell has lower susceptiblity than a standard I. walleriana from the greenhouse industry. Most importantly, none of the new hosts evaluated are as severely impacted by the disease as I. walleriana, so other Impatiens germplasm of many different species offers the prospect of lower disease susceptiblity through traditional plant breeding efforts. Impatiens balsamina seed have been found to carry oospores of Plasmopara obducens, indicating that seed of this species may be an overwintering location for the downy mildew.

Publications

  • Type: Other Status: Published Year Published: 2016 Citation: Daughtrey, M., Gilrein, D. and Vescera, M. 2016. Photographic Guide of Boxwood Pests and Diseases on Long Island. Cornell Cooperative Extension of Suffolk County, Riverhead, NY. 23 pp. http://ccesuffolk.org/resources/photographic-guide-of-boxwood-pests-diseases-on-long-island
  • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Kenaley, S. C. and Daughtrey, M. L. 2016. Making aecial-telial host connections: new insight into host alternation of the pear trellis and Japanese apple rust fungi in the Northeast (Abstr.) Phytopathology 106:S2.3. http://apsjournals.apsnet.org/doi/pdf/10.1094/PHYTO-106-4-S2.1
  • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Keach, J., Daughtrey, M., Bridgen, M., Salgado-Salazar, C. 2016. Susceptibility of Impatiens species to downy mildew caused by Plasmopara obducens (Abstr.) Phytopathology 106:S2.3. http://apsjournals.apsnet.org/doi/pdf/10.1094/PHYTO-106-4-S2.1
  • Type: Other Status: Published Year Published: 2016 Citation: Daughtrey, M., Keach, J., Hyatt, L., Bridgen, M., and Salgado, C. 2016. Downy mildew on impatiens: susceptibility of different Impatiens species. 2015 Annual Report Long Island Horticultural Research and Extension Center, Cornell University, p. 41. https://cuaes.cals.cornell.edu/sites/cuaes.cals.cornell.edu/files/shared/documents/2015LIHREC_complete_annual_report_sm.pdf
  • Type: Book Chapters Status: Published Year Published: 2016 Citation: Daughtrey, M., Hodge, K. T., and Shishkoff, N. 2016. The powdery mildews. Pages 191-204 in Ownley, B. H. and Trigiano, R., eds. Plant pathology concepts and laboratory exercises, 3rd ed. CRC Press. 582 pp.
  • Type: Other Status: Published Year Published: 2016 Citation: Daughtrey, M., Rychlik, P., Hyatt, L., Gilrein, D. and Kenaley, S. 2016. Alternate hosts for new rust diseases of crabapple and callery pear. 2015 Annual Report Long Island Horticultural Research and Extension Center, Cornell University, p. 53 https://cuaes.cals.cornell.edu/sites/cuaes.cals.cornell.edu/files/shared/documents/2015LIHREC_complete_annual_report_sm.pdf