Source: CORNELL UNIVERSITY submitted to NRP
IMPROVING THE UNDERSTANDING AND MANAGEMENT OF DISEASES AFFECTING LONG ISLAND VEGETABLE CROPS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
0223797
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Oct 1, 2010
Project End Date
Sep 30, 2013
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
Vegetable farms are an important part of the character of Suffolk County on Long Island (LI), which continues to be the most important agricultural county in NY. Fresh, local food is increasing in importance to consumers as concerns about health increases. An increasing number want food produced organically or with pesticides, preferably biopesticides, applied only when needed. Many families now visit farms for agri-tainment. For vegetable farming to remain a viable on LI, farmers need information on managing diseases under the unique LI conditions with new products, including organically-approved ones, and they need to know how production practices for improving soil health affect disease occurrence and severity. Farmers, aware that pesticide efficacy is not required for US registration, are reluctant to risk their crop by switching to a new product not tested for the disease under growing conditions similar to theirs. One proposed activity is to conduct replicated experiments to evaluate fungicides and other control practices for diseases observed to be important on LI. Control failures have occurred when pathogens developed resistance to fungicides being used. Thus another proposed activity is to monitor fungicide sensitivity in the powdery mildew fungus, the most important one affecting cucurbit crops in NY. This pathogen has a long history of developing resistance. Information from fungicide efficacy experiments and fungicide sensitivity monitoring will be used to guide fungicide recommendations and to justify requests for emergency registration of new fungicides in NY should this research indicate the need has arisen again. Baseline sensitivity data will also be obtained for new fungicides. Farmers also need to know how well new disease-resistant varieties perform in terms of yield and disease suppression in their area to make appropriate selections. Long-term projects with a goal of improving soil health will be continued through the proposed project. The project PI was instrumental in establishing research fields at Cornell's LI facility dedicated to organic production, long-term compost amendments, and reduced tillage production. Research is also being conducted on clover living mulch and biofumigant cover crops. Organic production is now being recognized as a viable way to grow vegetables on LI and elsewhere. Diseases can be problematic in organic as well as conventional production systems, but needs of organic farmers historically have received little attention from land-grant universities. The goal of this project is to work with both types of farmers to identify problems and develop solutions. Two groups of LI vegetable farmers (Organic and Vegetable Advisory Committees) already exist to assist with identifying needs. Conducting applied research to benefit farmers is a land-grant university mission and thus is appropriate use of public funds. With the goal of addressing farmer needs, this project has inherent flexibility to respond immediately to change, as has occurred recently with appearance of new diseases (basil downy mildew) and new strains of pathogens causing established diseases (cucurbit downy mildew and late blight).
Animal Health Component
(N/A)
Research Effort Categories
Basic
(N/A)
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2121429116030%
2161429116020%
2161460116010%
2161499116040%
Knowledge Area
212 - Pathogens and Nematodes Affecting Plants; 216 - Integrated Pest Management Systems;

Subject Of Investigation
1499 - Vegetables, general/other; 1460 - Tomato; 1429 - Cucurbits, other;

Field Of Science
1160 - Pathology;
Goals / Objectives
The overall project goal is to address disease management needs for vegetable crops grown on Long Island within organic and conventional production systems. Specific objectives are: 1. Survey representative conventional and organic farms yearly to determine what diseases are occurring and how they are being managed. 2. Conduct research where needed on important diseases identified through objective 1. 3. Evaluate biocompatible products for disease management within organic and conventional production systems. 4. Evaluate management practices for powdery mildew of cucurbits focusing on host plant resistance and fungicide resistance occurrence plus its management. 5. Examine cultural practices being investigated for improving soil health to assess potential positive or negative impacts on disease occurrence and severity. 6. Conduct exploratory research on alternative disease management practices to determine if the topic warrants further research and to obtain necessary preliminary data to support a request for funding from a granting agency. Examples for soil-borne pathogens include biofumigant cover crops and growing organic mulches between crop rows. Expected outputs to be generated as a result of this project include information on disease occurrence and management delivered to vegetable growers and extension specialists through newsletter articles, reports posted on-line, and presentations at summer Twilight meetings and winter grower meetings. Research results will be provided to scientists through annual scientific reports, presentations at scientific meetings, and scientific journal articles.
Project Methods
To achieve the intended outcome of addressing disease management needs for vegetable crops grown on LI, first needs will be identified by communicating with organic and conventional farmers and by inspecting their crops. Some needs have already been identified through this activity. Next management practices will be evaluated through replicated experiments with crops grown conventionally and organically at Cornell's research facility on LI (LIHREC) and through on-farm studies. Efficacy data on some control practices, including fungicides, is needed to improve control recommendations and to permit farmers to use a fungicide with a specific label for unlabeled diseases, such as the type of powdery mildew on tomato in the northeast. There are many biocompatible products on the market that often are broadly labeled for many diseases, which can be done without efficacy data. Farmers need comparative efficacy data for multiple products to ensure they select adequately effective ones. Fungicide resistance is a continuing issue with cucurbit powdery mildew to be addressed by conducting fungicide sensitivity assays for pathogen populations occurring in production and research fields, monitoring fungicide efficacy, and determining baseline sensitivity for new fungicides. Farmers will be involved with projects when possible, such as by assisting with evaluations of fruit from disease-resistant variety evaluations as done for previous projects. Evaluating disease resistant varieties provides farmers with information needed to select those appropriate for their operation while also monitoring for development of new pathogen races able to overcome host plant resistance. Potential management practices will be identified through on-farm observations, which previously revealed the need for established driveways rather than driving through pumpkin crops when applying fungicides which creates conditions favorable for Phytophthora blight, and by learning about practices being evaluated for other diseases, such as biofumigant cover crops for soil-borne pathogens. The specific methods that will be used to accomplish the project objectives will be the same as methods that proved useful in previous experiments or will be developed based on those experiences (including methods to introduce pathogens, promote disease development, produce crops, apply treatments, assess disease severity and yield). A strong foundation for this project is provided by the 21 years of research experience for the PI. Data will be statistically analyzed. Adequate facilities are available at LIHREC, which include laboratories, growth chambers, greenhouses, and amble field space with fields dedicated to long-term studies on organic, compost soil amendments, and reduced tillage. Fields are irrigated and protected through enclosure in a deer fence. Farm equipment is available for all aspects of vegetable production. Both hand-held and tractor-sprayers are used to apply treatments.

Progress 10/01/10 to 09/30/13

Outputs
Target Audience: The primary target audiences were farmers producing vegetable crops with organic or conventional production practices and extension specialists covering vegetable crops in other regions. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Providing training was not an identified component of this project when the proposal was written; however, the project did provide a learning opportunity for the Research Associate who assisted with the work. This individual had limited previous experience in the topic area when starting in this position with this project. The project scientist provided one-on-one training on procedures and provided education on general plant pathology concepts and about the specific diseases being investigated. Through this project training the Research Associate gained greater proficiency in plant pathology and research to be able to conduct additional projects. How have the results been disseminated to communities of interest? Information on the potential environmental benefits of topics being researched was provided to representatives of environmental groups on Long Island during an educational session held in 2013. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? The overall impact of this project has been to enable farmers to improve management of diseases affecting their vegetable crops, thereby improving the quality and yield of these crops and thus the profitability of the farm. First farmers need to know what diseases are occurring and how to recognize their symptoms. Disease occurrence and severity change routinely as a result of changes in pathogens and the environment. For example, pathogens can evolve such that they are no longer suppressed adequately by fungicides or varieties bred to be resistant (the fungus causing powdery mildew in cucurbit crops has done both). New pathogen strains may appear that are more aggressive on a host (this is the primary explanation for the emergence of the ‘potato disease’ late blight as a serious disease of tomato) or are able to cause disease on new hosts (pathogen causing Phytophthora blight in cucurbits and pepper now also can infect snap bean). Introduction to a region of new pathogens (such as the one causing downy mildew in basil, an herb commonly grown by diversified vegetable farmers) and uncommon pathogens (such as some viruses) can greatly impact crop production. Next step to achieving improved management is to provide farmers with information about the biology of the pathogen and the efficacy of management practices. An understanding of pathogen biology is the foundation of cultural management practices. All of the objectives of this project have been met. Goal #1. A key outcome obtained through surveying disease occurrence on farms was gaining knowledge by the project scientist about diseases for which research and/or extension activities were needed. Another key outcome was the farmers learning about these diseases, how to identify their symptoms, and how to manage them utilizing new information gained through research conducted during this project as well as what was already known about management. Goal #2. Three diseases identified as important through Goal #1 were Northern corn leaf blight in sweet corn, downy mildew in cucumber, and black rot in cabbage. New varieties and experimentals with resistance to these diseases were found by contacting breeders for these crops and seed company representatives. Replicated experiments were conducted to obtain information on yield, quality, and ability to resist these diseases. Experiments were conducted on Long Island and thus under the same conditions as the farms where these diseases are occurring. Farmers gained knowledge about the quality and quantity of the marketable produce from these varieties, which enables them to be able to choose suitable varieties for their operation. A series of experiments were conducted to evaluate new copper fungicides approved for use in organic production. This work was undertaken because farmers (organic and conventional) wanted to know if products differed in efficacy, amount of visible residue on produce (in particular tomato), and injury when applied to sensitive crops (such as lettuce and Brussels sprouts). These are all important considerations when selecting a product. Farmers were especially interested in a new product (Cueva) with a different type of copper ingredient from other products because it has a low copper use rate (less metallic copper equivalent) and shorter re-entry interval (4 hours compared to 12 – 48 hours for other products). These characteristics are especially important for organic farmers because they need to monitor their soils to document their use of copper fungicides does not result in copper levels increasing and they often need workers in crops like tomatoes every day. A key outcome was learning that the new copper fungicide leaves less residue and causes less damage, but is not as effective as other products. Goal #3. A key outcome of evaluating biopesticides in replicated experiments was determining efficacy of these products for foliar diseases of tomato. Most biopesticides are approved for organic production. Farmers are reluctant to try new products without documented efficacy for their intended use. Some biopesticides were ineffective in these experiments. Goal #4. Varieties of melon bred to have resistance to powdery mildew developed very few symptoms each year they were examined, while resistant squashes and pumpkins exhibited a low level of suppression with some becoming not significantly less severely affected than susceptible varieties included in the experiments for comparison. Knowledge of the level of control achievable with any management practice is important for implementing an integrated program. Based on the results of these experiments, farmers now know they need a much less intensive fungicide program with resistant melons than resistant squashes to achieve successful control of powdery mildew. Additionally, farmers were provided with information on yielding ability and fruit quality to enable them to select varieties suitable for their markets. Several different types of melons with resistance were released during this project; therefore diversity guided selection of varieties evaluated to provide farmers with maximum information. Investigating fungicide resistance in the cucurbit powdery mildew fungus is a unique aspect of this project and thus adds information to the knowledge base about this pathogen that is not being provided by other scientists. Fungicides that are most effective for this disease are prone to resistance development. Pathogen sensitivity to fungicides was monitored by conducting bioassays in fields (potted seedlings treated with fungicides at different concentrations are put near field-grown plants for a day to become exposed to the pathogen population there, then the seedlings are kept in a greenhouse until powdery mildew symptoms develop revealing what proportion of the pathogen population tolerates each fungicide dose) and by collecting pathogen isolates and testing them in the laboratory. Replicated experiments were conducted under field conditions to determine the efficacy of these fungicides, which was related to the information obtained about the pathogen’s sensitivity to these fungicides. With an understanding of how pathogen sensitivity to fungicides changes within and between seasons and of how efficacy of these fungicides also changes, it is possible to provide farmers with sound recommendations for fungicide programs. Goal #5. During this project, production fields were examined at farms where deep zone reduced tillage has been adopted for improving soil health and managing Phytophthora blight, an important disease that has proven difficult to control with fungicides alone. This production practice was examined in experiments conducted by the project scientist prior to this project. A substantial difference was observed in amount of blight in fields where reduced tillage was being used or had been used in previous years compared to other fields on these farms where this practice had not been used. Goal #6. Key outcomes of examining mustard biofumigation include demonstrating that this practice can be successfully implemented in the spring on Long Island prior to pumpkin or winter squash crops and can be a component of a successful management program for Phytophthora blight, the most important disease of these crops. Farmers learned the procedures for biofumigation through this project. Farmers have started using biofumigation. They report observing improved soil tilth and better crop health in addition to less blight.

Publications

  • Type: Journal Articles Status: Published Year Published: 2012 Citation: McGrath, M. T., and Hunsberger, L. K. 2012. Efficacy of fungicides for managing cucurbit powdery mildew and pathogen sensitivity to fungicides, 2011. Plant Disease Management Reports 6:V080.
  • Type: Journal Articles Status: Published Year Published: 2012 Citation: McGrath, M. T., and Hunsberger, L. K. 2012. Evaluation of biopesticides for managing downy mildew in basil, 2011. Plant Disease Management Reports 6:V099.
  • Type: Journal Articles Status: Published Year Published: 2012 Citation: McGrath, M. T., and Hunsberger, L. K. 2012. Evaluation of biopesticides for foliar diseases in organically-produced tomato, 2011. Plant Disease Management Reports 6:V100.
  • Type: Journal Articles Status: Published Year Published: 2012 Citation: McGrath, M. T., and Hunsberger, L. K. 2012. Evaluation of late blight resistant tomato cultivars and experimental hybrids on Long Island, NY, 2011. Plant Disease Management Reports 6:V127.
  • Type: Journal Articles Status: Published Year Published: 2012 Citation: McGrath, M. T., Menasha, S. R., and Hunsberger, L. K. 2012. Powdery mildew resistant acorn-type winter squash cultivar evaluation, 2011. Plant Disease Management Reports 6:V044.
  • Type: Journal Articles Status: Published Year Published: 2012 Citation: McGrath, M. T., Menasha, S. R., and Hunsberger, L. K. 2012. Powdery mildew resistant butternut-type winter squash cultivar evaluation, 2011. Plant Disease Management Reports 6:V043.
  • Type: Journal Articles Status: Published Year Published: 2012 Citation: McGrath, M. T., Menasha, S. R., and Hunsberger, L. K. 2012. Powdery mildew resistant muskmelon cultivar evaluation, 2011. Plant Disease Management Reports 6:V049.
  • Type: Journal Articles Status: Published Year Published: 2012 Citation: McGrath, M. T., Menasha, S. R., and Hunsberger, L. K. 2012. Powdery mildew resistant pumpkin cultivar evaluation, 2011. Plant Disease Management Reports 6:V098.
  • Type: Journal Articles Status: Published Year Published: 2012 Citation: McGrath, M. T., Menasha, S. R., and Hunsberger, L. K. 2012. Powdery mildew resistant yellow summer squash cultivar evaluation, 2011. Plant Disease Management Reports 6:V048.
  • Type: Journal Articles Status: Published Year Published: 2012 Citation: McGrath, M. T., Menasha, S. R., and Hunsberger, L. K. 2012. Powdery mildew resistant zucchini squash cultivar evaluation, 2011. Plant Disease Management Reports 6:V045.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Efficacy of fungicides for managing powdery mildew in pumpkin, 2012. Plant Disease Management Reports 7:V013.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: McGrath, M. T. and LaMarsh, K. A. 2013. Evaluation of biopesticides for managing foliar diseases in organically-produced tomato, 2012. Plant Disease Management Reports 7:V106.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: McGrath, M. T. and LaMarsh, K. A. 2013. Evaluation of biopesticides for managing Phytophthora blight in cucurbits, 2012. Plant Disease Management Reports 7:V012.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: McGrath, M. T. and LaMarsh, K. A. 2013. Evaluation of biopesticides for managing Phytophthora blight in pepper, 2012. Plant Disease Management Reports 7:V017.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: McGrath, M. T., Menasha, S. R., and LaMarsh, K. A. 2013. Evaluation of downy mildew resistance in experimental hybrids of cucumber, 2012. Plant Disease Management Reports 7:V018.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: McGrath, M. T., Menasha, S. R., and LaMarsh, K. A. 2013. Evaluation of Phytophthora-resistant bell pepper cultivars with and without a fungicide program, 2012. Plant Disease Management Reports 7:V016.
  • Type: Journal Articles Status: Published Year Published: 2013 Citation: McGrath, M. T., Menasha, S. R., and LaMarsh, K. A. 2013. Powdery mildew resistant melon cultivar evaluation, 2012. Plant Disease Management Reports 7:V014.
  • Type: Journal Articles Status: Accepted Year Published: 2014 Citation: McGrath, M. T. and LaMarsh, K. A. 2014. Comparison of organic and conventional copper fungicides for powdery mildew in zucchini, 2013. Plant Disease Management Reports 8:(accepted).
  • Type: Journal Articles Status: Accepted Year Published: 2014 Citation: McGrath, M. T. and LaMarsh, K. A. 2014. Efficacy of fungicides for managing powdery mildew in pumpkin, 2013. Plant Disease Management Reports 8:(accepted).
  • Type: Journal Articles Status: Accepted Year Published: 2014 Citation: McGrath, M. T. and LaMarsh, K. A. 2014. Evaluation of biopesticides for foliar diseases in organically-produced tomato, 2013. Plant Disease Management Reports 8:(accepted).
  • Type: Journal Articles Status: Accepted Year Published: 2014 Citation: McGrath, M. T., Menasha, S. R., and LaMarsh, K. A. 2014. Powdery mildew resistant melon cultivar evaluation, 2013. Plant Disease Management Reports 8:(accepted).
  • Type: Conference Papers and Presentations Status: Published Year Published: 2011 Citation: McGrath, M. T., Fox, G. M., and Hunsberger, L. K. 2011. Control of downy mildew (Pseudoperonospora cubensis) in organically-produced cucumber with biopesticides. Northeastern Division of the American Phytopathological Society annual meeting. (presented 10/11).
  • Type: Conference Papers and Presentations Status: Published Year Published: 2011 Citation: McGrath, M. T., Menasha, S. R., Fox, G. M., and Hunsberger, L. K. 2011. Evidence of reduced suppression of powdery mildew (Podosphaera xanthii) provided by resistant muskmelon (Cucumis melo) cultivars in NY. Northeastern Division of the American Phytopathological Society annual meeting. (presented 10/11).
  • Type: Conference Papers and Presentations Status: Published Year Published: 2012 Citation: McGrath, M. T. 2012. Fungicide resistance: Current situation and management challenges. 7th International IPM Symposium. (presented 3/12).
  • Type: Conference Papers and Presentations Status: Published Year Published: 2012 Citation: McGrath, M. T. 2012. Managing powdery mildew in cucurbit crops with biopesticides and resistant varieties. 7th International IPM Symposium. (poster presented 3/12).
  • Type: Conference Papers and Presentations Status: Published Year Published: 2012 Citation: McGrath, M. T., Stevenson, K. L. and Wyenandt, C. A. 2012. Occurrence of fungicide resistance in pathogens of non-solanaceous vegetable crops. In Workshop on Fungicide Resistance in North America in the 21st Century, American Phytopathological Society Annual Meeting. (presented 8/12).
  • Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: McGrath, M. T. 2013. Efficacy of fungicides with resistance risk for cucurbit powdery mildew and fungicide sensitivity of Podosphaera xanthii in New York. American Phytopathological Society annual meeting. (poster presented 8/13).
  • Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: McGrath, M. T. and Menasha, S. R. 2013. Managing Phytophthora blight with biofumigation. American Phytopathological Society annual meeting. (poster presented 8/13).
  • Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: McGrath, M. T. and LaMarsh, K. A. 2013. Cross resistance among some SDHI fungicides documented in Podosphaera xanthii, the cucurbit powdery mildew pathogen. Northeastern Division of the American Phytopathological Society annual meeting. (presented 10/13).
  • Type: Conference Papers and Presentations Status: Other Year Published: 2013 Citation: McGrath, M. T. 2013. Biofumigation and reduced tillage as components of successful integrated management programs for Phytophthora capsici. 4th International Phytophthora capsici Conference. (presented 12/13).


Progress 10/01/11 to 09/30/12

Outputs
OUTPUTS: Project goal, which is to optimize disease control for conventionally and organically produced vegetable crops, was achieved by conducting experiments, monitoring disease occurrence, assessing disease management on farms, disseminating results at several events, providing diagnostic services, and developing products including newsletter articles and web pages. Activities included experiments conducted to evaluate resistant varieties and biopesticides, important management tools for producing crops organically as well as conventionally. Experiments targeted important diseases in the northeastern US: foliar diseases in tomato, downy mildew in basil, downy mildew in cucumber, powdery mildew in cucurbits, rust in sweet corn, black rot in cabbage, and Phytophthora blight in pumpkin, squash and pepper. Cucurbit powdery mildew pathogen exists as races differentiated on melons. Successful control with resistant varieties necessitates knowing what races are present. To determine this melon differentials were grown. Conventional fungicides were also evaluated for powdery mildew. Most fungicides examined are already registered, thus results obtained are of immediate utility for growers. Development of fungicide resistance is a constraint to effectively managing diseases, especially with cucurbit powdery mildew. Several fungicides suspected of being affected by resistance or considered at-risk were tested by applying them singly with a tractor-sprayer every week to field-grown pumpkin in a replicated experiment. Mildew severity was determined weekly to assess control. Also, a seedling bioassay was used to examine sensitivity to fungicides of the powdery mildew pathogen in populations during the growing season. Additionally, pathogen isolates were collected and are being tested in the laboratory with a leaf disk assay to determine sensitivity of individuals to currently registered fungicides and also new ones to obtain baseline sensitivity data and to determine if there is cross resistance among old and new fungicides in the same chemical group. Following up on previous successes, mustard biofumigant cover crop was used as the first component of an integrated management program for Phytophthora blight of pumpkin in a field where blight was severe in 2011. Several production fields were monitored to assess impact of management practices and environmental conditions on development of diseases. Other activities included participating in the cucurbit downy mildew forecasting program and leading the monitoring program for basil downy mildew, a new disease in the US affecting greenhouse and field crops in NY. Research results and observations on diseases were shared with growers at several events, including the Long Island Horticultural Research and Extension Center Annual Plant Science Day and Annual Summer Twilight Meeting for Organic Growers. 10 presentations were made at 10 grower meetings and 2 meetings for extension faculty and specialists. Articles were written for weekly and monthly newsletters, as well as for the Vegetable MD OnLine web site (http://vegetablemdonline.ppath.cornell.edu/). Research results were also presented at 4 scientific meetings. PARTICIPANTS: Karen LaMarsh, Research Support Specialist, assisted with conducting experiments and analyzing data. Sandra Menasha, Vegetable Specialist, Cornell Cooperative Extension-Suffolk County, NY, cooperated on variety evaluation experiments. Amanda Gardner, Research Assistant, helped with conducting experiments. Scott Erickson, Research Assistant, helped with conducting experiments. Lucas Sisson, Research Assistant, helped with conducting experiments. Geoffrey Griffiths, Research Assistant, helped with conducting experiments. Ashley Clasen, Research Assistant, helped with conducting experiments. Shauna Ryan, Research Assistant, helped with conducting experiments. Emily Benazzi, Research Assistant, helped with conducting experiments. Daniel Miller, Research Assistant, helped with conducting experiments. Joseph Pugliese, Research Assistant, helped with conducting experiments. TARGET AUDIENCES: Extension specialists in New York and other states. Vegetable growers in New York and other states. Plant breeders. Agricultural chemical industry representatives. IR-4 Program. IR-4 Biopesticide Research Program. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Useful information was obtained through research and observations on vegetable disease occurrence and management in 2012 to help growers to optimize management. Powdery mildew resistant melon varieties provided excellent suppression. Based on observations of mildew occurrence on the melon differentials, race 1 of the powdery mildew pathogen was common on Long Island in 2012, race 2 also occurred, and there was some evidence that additional race(s) might have been present at a low level. Among fungicides currently registered for powdery mildew, Pristine (contains FRAC Code 7 and 11 ingredients) applied at its highest label rate was ineffective. In previous years at this location, pathogen isolates resistant to both components of this fungicide have been detected, and the fungicide has exhibited variable performance. Among the 55 isolates collected in Sep 2011 when Pristine was effective, 79% were resistant to Code 11 chemistry while only 6% were resistant to the Code 7 ingredient in Pristine (tolerated 500 ppm). Ineffectiveness in 2012 suggests resistant isolates were more common. Resistant isolates were detected with the in-field seedling bioassay conducted early in disease development (mid-Jul 2012). Fontelis (FRAC 7), a chemically-related fungicide registered in 2012, was only somewhat more effective than Pristine. Procure (FRAC 3) applied at its highest label rate was effective. In lab assays only 4% of 2011 isolates tolerated 80 ppm of myclobutanil, a FRAC 3 ingredient. Similar control was achieved with Mettle, a new FRAC 3 fungicide not registered yet for this use. Quintec (FRAC 13) was highly effective through the last assessment when the other registered fungicides were no longer effective. The seedling bioassay revealed a low proportion of the pathogen population tolerated 10 ppm of the active ingredient in Quintec. The cucurbit downy mildew sentinel plot provided useful information on disease occurrence for LI growers and the forecasting program. New resistant cucumber varieties did not adequately suppress downy mildew. Tomato with Ph2 and Ph3 genes were very resistant to late blight genotype US-23. Phytophthora blight was less severe in research and commercial fields where there was a history of crops being grown using reduced tillage. The integrated management program was also successful. A surprising observation was blight occurring in 6 fields managed by 4 different growers that have been used to produce a non-host crop for many years. Blight development was delayed with 3 of the resistant pepper varieties evaluated. Surprisingly, there was no benefit detected of using an integrated management program (fungicides applied to resistant variety) over fungicides alone. The web-based monitoring program for basil downy mildew proved useful for tracking and sharing information about occurrence of this new disease amongst extension specialists, producers, and gardeners. It has proven difficult to control with fungicides. Disease levels were low overall in research fields used to evaluate biopesticides for Phytophthora blight and foliar disease in tomato; however, severity usually was numerically lower in treated than non-treated plots.

Publications

  • McGrath, M. T., and Hunsberger, L. K. 2012. Efficacy of fungicides for managing cucurbit powdery mildew and pathogen sensitivity to fungicides, 2011. Plant Disease Management Reports 6:V080.
  • McGrath, M. T., and Hunsberger, L. K. 2012. Efficacy of fungicides for managing downy mildew in cucumber, 2011. Plant Disease Management Reports 6:V008.
  • McGrath, M. T., and Hunsberger, L. K. 2012. Efficacy of Vivando for managing powdery mildew in cucurbit crops, 2011. Plant Disease Management Reports 6:V007.
  • McGrath, M. T., and Hunsberger, L. K. 2012. Evaluation of biopesticides for managing downy mildew in basil, 2011. Plant Disease Management Reports 6:V099.
  • McGrath, M. T., and Hunsberger, L. K. 2012. Evaluation of biopesticides for foliar diseases in organically-produced tomato, 2011. Plant Disease Management Reports 6:V100.
  • McGrath, M. T., and Hunsberger, L. K. 2012. Evaluation of fungicides for powdery mildew in tomato, 2011. Plant Disease Management Reports 6:V081.
  • McGrath, M. T., and Hunsberger, L. K. 2012. Evaluation of late blight resistant tomato cultivars and experimental hybrids on Long Island, NY, 2011. Plant Disease Management Reports 6:V127.
  • McGrath, M. T., Menasha, S. R., and Hunsberger, L. K. 2012. Powdery mildew resistant acorn-type winter squash cultivar evaluation, 2011. Plant Disease Management Reports 6:V044.
  • McGrath, M. T., Menasha, S. R., and Hunsberger, L. K. 2012. Powdery mildew resistant butternut-type winter squash cultivar evaluation, 2011. Plant Disease Management Reports 6:V043.
  • McGrath, M. T., Menasha, S. R., and Hunsberger, L. K. 2012. Powdery mildew resistant muskmelon cultivar evaluation, 2011. Plant Disease Management Reports 6:V049.
  • McGrath, M. T., Menasha, S. R., and Hunsberger, L. K. 2012. Powdery mildew resistant pumpkin cultivar evaluation, 2011. Plant Disease Management Reports 6:V098.
  • McGrath, M. T., Menasha, S. R., and Hunsberger, L. K. 2012. Powdery mildew resistant yellow summer squash cultivar evaluation, 2011. Plant Disease Management Reports 6:V048.
  • McGrath, M. T., Menasha, S. R., and Hunsberger, L. K. 2012. Powdery mildew resistant zucchini squash cultivar evaluation, 2011. Plant Disease Management Reports 6:V045.


Progress 10/01/10 to 09/30/11

Outputs
OUTPUTS: The goal of this project, which is to optimize disease control for conventionally and organically produced vegetable crops, was obtained by conducting experiments, monitoring disease occurrence, assessing disease management on farms, disseminating results at several events, providing diagnostic services, and developing products including newsletter articles and web pages. Activities included experiments conducted to evaluate resistant varieties and biopesticides, which are important management tools for producing crops organically as well as conventionally. These experiments targeted important diseases affecting crops in the northeastern US: foliar diseases in tomato, downy mildew in basil, and powdery mildew in cucurbits. Conventional fungicides were also evaluated for powdery mildew in cucurbits. Most fungicides examined are already registered, thus results obtained are of immediate utility for growers. Development of fungicide resistance is a constraint to effectively managing diseases, especially with the cucurbit powdery mildew fungus, which has demonstrated its ability to develop resistance to several different fungicide classes. Therefore, several fungicides suspected of being affected by resistance or considered at-risk were tested by applying them singly with a tractor-sprayer every week to field-grown pumpkin in a replicated experiment. Mildew severity was determined weekly to assess control. It is not possible to assess impact of resistance on control with the recommended use pattern for at-risk fungicides, which is to alternate among at-risk products and to tank-mix them with multi-site fungicides that have low resistance risk. A seedling bioassay was used to examine sensitivity to fungicides of the powdery mildew fungus in pathogen populations in commercial fields during the growing season. Additionally, pathogen isolates were collected and are being tested in the laboratory with a leaf disk assay to determine sensitivity of individuals. This procedure is also being used to examine sensitivity to new fungicides. Mustard biofumigant cover crop, a mustard meal product, and a soil-applied organically-approved biopesticide (Serenade Soil) were evaluated for Phytophthora blight in squash. Several production fields were monitored to assess impact of management practices and environmental conditions on development of diseases. Other activities included participating in the cucurbit downy mildew forecasting program and leading the monitoring program for basil downy mildew, a new disease in the US affecting greenhouse and field crops in NY. Research results and observations on diseases were shared with growers at several events, including the Long Island Horticultural Research and Extension Center Annual Plant Science Day and Annual Summer Twilight Meeting for Vegetable Growers. 19 presentations were made at ten grower meetings and two meetings for extension faculty and specialists. Articles were written for weekly and monthly newsletters, as well as for the Vegetable MD OnLine web site (http://vegetablemdonline.ppath.cornell.edu/). Research results were also presented at four scientific meetings. PARTICIPANTS: Laura Hunsberger, Research Support Specialist, assisted with conducting experiments and analyzing data. Sandra Menasha, Vegetable Specialist, Cornell Cooperative Extension-Suffolk County, NY, cooperated on variety evaluation experiments. Michael Finck, Research Assistant, helped with conducting experiments. Karen Lamarsh, Research Assistant, helped with conducting experiments. Lucas Sisson, Research Assistant, helped with conducting experiments. Geoffrey Griffiths, Research Assistant, helped with conducting experiments. Ashley Clasen, Research Assistant, helped with conducting experiments. Grayham Seeberger, Research Assistant, helped with conducting experiments. Scott Erickson, Research Assistant, helped with conducting experiments. TARGET AUDIENCES: Extension specialists in New York and other states. Vegetable growers in New York and other states. Plant breeders. Agricultural chemical industry representatives. IR-4 Program. IR-4 Biopesticide Research Program. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Useful fundamental and applied knowledge was obtained through research and observations on vegetable disease management in 2011 despite the fact it was a poor growing season. Environmental conditions were atypical for the region during late summer, with a hurricane plus rain occurring on more days than usual, adversely affecting plant growth while promoting disease development. Project success was affected. Excessive rain provided conditions that were especially ideal for Phytophthora blight. This disease was very severe in many grower fields, even where fungicides were used that provided good control in previous years. Treatments tested were ineffective. None of the biopesticides evaluated were effective for foliar diseases in tomato; however, neither was the conventional fungicide included for comparison. MilStop, Timorex Gold, and Sonata applied with copper demonstrated some promise. Several late blight resistant tomato varieties and experimentals were rated better in researcher and consumer evaluations than a commonly-grown susceptible variety. Powdery mildew resistant melon varieties provided excellent suppression, thus a new pathogen race occurring in the southeastern US did not spread to LI in 2011 contrasting with 2010. Resistant squash and pumpkin varieties were not as effective, substantiating previous results. Genetics of resistance in these crops is different from melons. With some cucurbit crop types more effective control was achieved with homozygous than heterozygous resistance (acorn squash, pumpkin) or with integrated control (fungicide applied to resistant variety) than with fungicides alone (acorn squash, butternut squash, pumpkin). Neither was the case with the summer squash varieties tested. Heterozygous resistant acorn squash, zucchini and pumpkin varieties were ineffective. Resistant zucchini varieties also exhibited different suppression; the one with the fewest genes was ineffective. Powdery mildew was controlled on upper leaf surfaces by products in all 3 recommended fungicide classes: FRAC code 13 (Quintec), 7 (Pristine), and 3 (Procure). Severity was lower on plants treated with new fungicides (7, U6 and U8). A leaf disk bioassay used to determine fungicide sensitivity of pathogen isolates obtained late in the 2010 growing season revealed that most, 97% and 98%, were resistant to FRAC code 1 and 11 fungicides, respectively, 43% were resistant to boscalid (7). One isolate tolerated 80 ppm myclobutanil (code 3), 40 ppm quinoxyfen (13) and was fully resistant to boscalid and code 1 and 11 fungicides. Such isolates with resistance or elevated insensitivity (compared to other isolates) to all labeled fungicide chemistries is a concern for continued effective management of cucurbit powdery mildew with currently-registered fungicides. Resistance was also detected in crops with an in-field seedling bioassay in 2011. Maintaining a cucurbit downy mildew sentinel plot provided essential information for the forecasting program. The web-based monitoring program for basil downy mildew proved useful for tracking and sharing information about occurrence of this new disease amongst extension specialists, producers, and gardeners.

Publications

  • McGrath, M. T., Menasha, S. R., and Hunsberger, L. K. 2011. Powdery mildew resistant zucchini squash cultivar evaluation, 2010. Plant Disease Management Reports 5:V095.
  • McGrath, M. T., Menasha, S. R., and Hunsberger, L. K. 2011. Powdery mildew resistant pumpkin cultivar evaluation, 2009. Plant Disease Management Reports 5:V099.
  • McGrath, M. T., Menasha, S. R., and Hunsberger, L. K. 2011. Powdery mildew resistant pumpkin cultivar evaluation, 2010. Plant Disease Management Reports 5:V101.
  • Gobena, D., McGrath, M. T., and Lamour, K. 2011. Survival and spread of Phytophthora capsici on Long Island, New York. Mycological Progress (on-line publication). DOI 10.1007/s11557-011-0787-5.
  • Ojiambo, P. S., Holmes, G. J., Britton, W., Keever, T., Adams, M. L., Babadoost, M., Bost, S. C., Boyles, R., Brooks, M., Damicone, J., Draper, M. A., Egel, D. S., Everts, K. L., Ferrin, D. M., Gevens, A. J., Gugino, B. K., Hausbeck, M. K., Ingram, D. M., Isakeit, T., Keinath, A. P., Koike, S. T., Langston, D., McGrath, M. T., Miller, S. A., Mulrooney, R., Rideout, S., Roddy, E., Seebold, K. W., Sikora, E. J., Thornton, A., Wick, R. L., Wyenandt, C. A., and Zhang, S. 2011. Cucurbit downy mildew ipmPIPE: A next generation web-based interactive tool for disease management and extension outreach. Online. Plant Health Progress doi:10.1094/PHP-2011-0411-01-RV. Public summary: http://www.plantmanagementnetwork.org/php/elements/sum.aspxid=9442&p hoto=5281
  • McGrath, M. T. and Hunsberger, L. K. 2011. Effectiveness for cucurbit powdery mildew of fungicides prone to resistance development. Phytopathology 100:S.
  • McGrath, M. T., Rivara, K. L., and Hunsberger, L. K. 2011. Sensitivity of the cucurbit powdery mildew pathogen to fungicides prone to resistance development. Phytopathology 100:S.
  • McGrath, M. T., and Hunsberger, L. K. 2011. Efficacy of fungicides for managing cucurbit powdery mildew and pathogen sensitivity to fungicides, 2010. Plant Disease Management Reports 5:V104.
  • McGrath, M. T., and Hunsberger, L. K. 2011. Evaluation of biopesticides for managing downy mildew in basil, 2010. Plant Disease Management Reports 5:V098.
  • McGrath, M. T., and Hunsberger, L. K. 2011. Evaluation of biopesticides for managing downy mildew in organically produced cucumber, 2010. Plant Disease Management Reports 5:V100.
  • McGrath, M. T., Menasha, S. R., and Hunsberger, L. K. 2011. Evaluation of powdery mildew resistant muskmelon cultivars, 2010. Plant Disease Management Reports 5:V106.
  • McGrath, M. T., Menasha, S. R., and Hunsberger, L. K. 2011. Evaluation of powdery mildew resistant muskmelon cultivars producing personal-sized fruit, 2010. Plant Disease Management Reports 5:V105.
  • McGrath, M. T., Menasha, S. R., and Hunsberger, L. K. 2011. Powdery mildew resistant acorn-type winter squash cultivar evaluation, 2010. Plant Disease Management Reports 5:V096.
  • McGrath, M. T., Menasha, S. R., and Hunsberger, L. K. 2011. Powdery mildew resistant butternut-type winter squash cultivar evaluation, 2010. Plant Disease Management Reports 5:V097.
  • McGrath, M. T., Menasha, S. R., and Hunsberger, L. K. 2011. Powdery mildew resistant yellow summer squash cultivar evaluation, 2010. Plant Disease Management Reports 5:V094.