Progress 10/01/11 to 09/30/14
Outputs
Target Audience: Target audiences include vegetable farmers, private consultants, Cooperative Extension specialists and field staff, fungicide companies, vegetable fresh cut processors, seed companies and canning/processing companies. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? The graduate student involved in the project has presented her work at grower meetings and attended and will present at the national meeting of the American Phytopathological Society. How have the results been disseminated to communities of interest? The results have been disseminated in annual meetings of the New York State Cabbage Research and Development Board. Information was also disseminated in presentations at the annual Empire State Producers Expo. And additional information was disseminated through Cornell Cooperative Extension Vegetable Program newsletters, and summer grower meetings. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
1. From the field seasons of 2010 - 2014, we now have 67 New York isolates that are now genetically pure single conidial isolates. Genomic DNA has been extracted from these cultures and the DNA has been amplified by polymerase chain reaction (PCR) using species specific primers. All of the cultures analyzed have been successfully amplified with Alternaria brassicicola specific primers. It is now clear that there is one main species in New York that causes Alternaria leaf spot on cabbage - Alternaria brassicicola. 2. Pathogenicity tests were completed on whole plants and detached leaves. All isolates were pathogenic with no statistical differences in aggressiveness. 3. Fungicide sensitivity tests on whole plants and in vitro have been completed. Whole plant tests results were variable, therefore the approach was revised and the isolates were grown on agar media in the presence of the test fungicides. There is no evidence of fungicide resistance in the New York isolates at this time. The results imply that unsatisfactory control of Alternaria leaf spot in commercial fields is a result of other factors such as poor coverage of the leaves with fungicide or incorrect timing of the fungicide application. 4. Spore traps were again installed in a field of cabbage in Geneva, NY in 2014, to determine when spores of A. brassicicola are present in wind currents. The traps were located in a field that had a history of Alternaria leaf spot on cabbage the previous year. The spore traps are composed of a small electric motor which rotates two small metal rods. The rods are coated in silicone grease and catch particulate matter in the air. The rods were collected twice weekly throughout the growing season from May through September. DNA was then extracted from the rods using a DNA isolation kit. The DNA extractions will need further analyzing to determine if A. brassicicola spore DNA is present and when the spores were first detected. 5. Recommendations for control of Alternaria leaf spot were revised to incorporate the knowledge gained on fungicide sensitivity and efficacy of conventional and bio-based products. These results were reported to brassica growers at several meetings including the cabbage research and development meeting in December 2014, summer grower meetings in counties in Eastern, Central and Western NY in August, and the 2014 and 2015 Empire State Fruit and Vegetable Expo in Syracuse NY.
Publications
- Type:
Other
Status:
Published
Year Published:
2014
Citation:
Lange, H.W., Seaman, A.J. 2014. Evaluation of fungicides allowed for organic production on alternaria blight of cauliflower, 2013. Plant Dis Manag. Rep. 8V261. Online publication. Doi: 10.1094/PDMR08. The American Phytopathological Society, St. Paul, MN
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Progress 10/01/13 to 09/30/14
Outputs
Target Audience: Target audiences include vegetable farmers, private consultants, Cooperative Extension specialists and field staff, fungicide companies, vegetable fresh cut processors, seed companies, and canning/processing companies. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? The graduate student involved in the project has presented her work at grower meetings and attended and will present at the national meeting of the American Phytopathological Society. How have the results been disseminated to communities of interest? The results have been disseminated in annual meetings of the New York State Cabbage Research and Development Board. Information was also disseminated in presentations at the annual Empire State Producers Expo. And additional information was disseminated through Cornell Cooperative Extension Vegetable Program newsletters, and summer grower meetings. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
1. From the field seasons of 2010 - 2014, we now have 67 New York isolates that are now genetically pure single conidial isolates. Genomic DNA has been extracted from these cultures and the DNA has been amplified by polymerase chain reaction (PCR) using species specific primers. All of the cultures analyzed have been successfully amplified with Alternaria brassicicola specific primers. It is now clear that there is one main species in New York that causes Alternaria leaf spot on cabbage – Alternaria brassicicola. 2. Pathogenicity tests were completed on whole plants and detached leaves. All isolates were pathogenic with no statistical differences in aggressiveness. 3. Fungicide sensitivity tests on whole plants and in vitro have been completed. Whole plant tests results were variable, therefore the approach was revised and the isolates were grown on agar media in the presence of the test fungicides. There is no evidence of fungicide resistance in the New York isolates at this time. The results imply that unsatisfactory control of Alternaria leaf spot in commercial fields is a result of other factors such as poor coverage of the leaves with fungicide or incorrect timing of the fungicide application. 4. Spore traps were again installed in a field of cabbage in Geneva, NY in 2014, to determine when spores of A. brassicicola are present in wind currents. The traps were located in a field that had a history of Alternaria leaf spot on cabbage the previous year. The spore traps are composed of a small electric motor which rotates two small metal rods. The rods are coated in silicone grease and catch particulate matter in the air. The rods were collected twice weekly throughout the growing season from May through September. DNA was then extracted from the rods using a DNA isolation kit. The DNA extractions will need further analyzing to determine if A. brassicicola spore DNA is present and when the spores were first detected. 5. Recommendations for control of Alternaria leaf spot were revised to incorporate the knowledge gained on fungicide sensitivity and efficacy of conventional and bio-based products. These results were reported to brassica growers at several meetings including the cabbage research and development meeting in December 2014, summer grower meetings in counties in Eastern, Central and Western NY in August, and the 2014 and 2015 Empire State Fruit and Vegetable Expo in Syracuse NY.
Publications
- Type:
Other
Status:
Published
Year Published:
2014
Citation:
Lange, H. W., Seaman, A. J. 2014. Evaluation of fungicides allowed for organic production on alternaria blight of cauliflower, 2013. Plant Dis Manag. Rep. 8:V261. Online publication. Doi: 10.1094/PDMR08. The American Phytopathological Society, St. Paul, MN.
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Progress 10/01/12 to 09/30/13
Outputs
Target Audience: Target audiences include vegetable farmers, private consultants, Cooperative Extension specialists and field staff, fungicide companies, vegetable fresh cut processors, seed companies, and canning/processing companies. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest? The results have been disseminated in annual meetings of the New York State Cabbage Research and Development Board. Information was also disseminated in presentations at the annual Empire State Producers Expo. And additional information was disseminated through Cornell Cooperative Extension Vegetable Program newsletters. What do you plan to do during the next reporting period to accomplish the goals? In the next reporting period, work will continue towards the development of a rapid pathogenicity test for the isolates that have been collected. The spore trapping research conducted during the summer of 2013 will be repeated and the DNA will be analyzed using QPCR. The revision of the control recommendations for Alternaria leaf spot will be completed.
Impacts
What was accomplished under these goals?
From the field seasons of 2010, 2011, and 2012, we now have 44 New York isolates that are now pure single spore cultures. Genomic DNA has been extracted from these cultures and the DNA has been amplified by polymerase chain reaction (PCR) using species specific primers. All of the cultures analyzed have been successfully amplified with Alternaria brassicicola specific primers. There was one isolate that had the appearance of another species, but it was ultimately identified as A. brassicicola using molecular tools. It is now clear that there is one main species in New York that causes Alternaria leaf spot on cabbage – Alternaria brassicicola. Pathogenicity tests have been conducted on whole plants and detached leaves. Work will continue towards development of a more rapid test for evaluating pathogenicity using leaf discs incubated in controlled temperature and light conditions. Fungicide sensitivity tests on whole plants and in vitro have been completed. Whole plant tests results were variable, therefore the approach was revised and the isolates were grown on agar media in the presence of the test fungicides. Ten isolates from cabbage and six isolates from Brussels sprouts were selected for the study. The treatments were: Untreated Control, Azoxystrobin at 0.001, 0.01, 0.1, 1, 10 parts per million (ppm), Boscalid at 0.001, 0.01, 0.1, 1, 10 ppm, Chlorothalonil at 0.001, 0.01, 0.1, 1, 10 ppm. The results from this study were consistent and repeatable. Boscalid (Endura) was the most effective fungicide in reducing growth of all the isolates on agar media at high concentrations (1 and 10 parts per million). The growth patterns of all the isolates on the fungicide amended media were similar. None of the isolates were insensitive (high growth rate) to the fungicides. Thus, there is no evidence of fungicide resistance in the New York isolates at this time. The results imply that unsatisfactory control of Alternaria leaf spot in commercial fields is a result of other factors such as poor coverage of the leaves with fungicide or incorrect timing of the fungicide application. Spore traps were installed in a field of cabbage in Geneva, NY, to determine when spores of A. brassicicola are present in wind currents. The traps were located in a field that had a history of Alternaria leaf spot on cabbage the previous year. The spore traps are composed of a small electric motor which rotates two small metal rods. The rods are coated in grease and catch particulate matter in the air. The rods were collected twice weekly throughout the growing season from May through November. DNA was then extracted from the rods using a DNA isolation kit. The DNA extractions will need further analyzing to determine if A. brassicicola spore DNA is present and when the spores were first detected. Weekly visual ratings of disease were also taken in the latter stage of the growing season. Unfortunately, visual symptoms of disease did not appear until September 10, 2013, and very little disease developed in the plot this year. Recommendations for control of Alternaria leaf spot are being revised to incorporate the knowledge gained on fungicide sensitivity and efficacy of conventional and bio-based products. This will be completed in 2014. A new fact sheet on Alternaria leaf spot was posted to the Dillard Lab web site: http://web.pppmb.cals.cornell.edu/dillard/pdf/alternaria.pdf
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Strauss, J.A., Bitsadze, N., and Dillard, H.R. 2013. Evaluation of fungicides for control of Alternaria leaf spot in Brussels sprouts, 2012. Plant Disease Management Reports 7:V055.
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2013
Citation:
Scheufele, S.B. 2013. Alternaria leaf spot of Brassica crops: disease incidence and sustainable management. MS Thesis, Cornell University.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2013
Citation:
Gorny, A., Kreis, R., and Dillard, H. 2013. Alternaria leaf spot of cabbage.
http://web.pppmb.cals.cornell.edu/dillard/pdf/alternaria.pdf
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Strauss, J.A., Bitsadze, N., and Dillard, H.R. 2013. Evaluation of fungicides for control of Alternaria leaf spot in cabbage, 2012. Plant Disease Management Reports 7:V054.
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Scheufele, S.B. and Dillard, H.R. 2013. Evaluation of organic fungicides and soil amendments for control of Alternaria leaf spot in cabbage, 2012. Plant Disease Management Reports 7:V032.
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Progress 10/01/11 to 09/30/12
Outputs
OUTPUTS: Plant tissues showing symptoms of Alternaria leaf spot were collected from a variety of cruciferous vegetable crops grown across New York State. Forty four pure cultures were used to generate single conidial isolates. DNA was extracted from each single spore culture and amplified by PCR using species specific primers. All single conidial cultures analyzed were successfully amplified with Alternaria brassicicola specific primers. The isolates were used in greenhouse studies to compare aggressiveness and fungicide sensitivity of the isolates. Significant variability was found among isolates with no clear patterns related to region or crop specificity. A replicated trial was conducted in a field with a history of Alternaria leaf spot to determine when viable spores are produced from overwintering infested debris. The field was planted to kale and spore traps were put in the field to monitor spore dissemination. Treatments included bare ground, black plastic mulch, biodegradable black plastic mulch and straw mulch. All mulch types reduced disease incidence and straw mulch significantly reduced disease incidence and increased plant growth. A field trial was conducted to determine whether any commercially available biocontrol strains or soil amendments are effective in reducing disease severity in the field. The treatments had no effect on Alternaria leaf spot incidence or severity. A field trial was conducted to evaluate efficacy of registered materials and new materials that will soon be registered for use on crucifers. Final disease severity on the lower, mid, upper leaves and cabbage head in all of the treated plots was statistically less than in the control plot. Disease severity was generally greatest on the lower leaves. A new fungicide, Luna Experience, gave the best control and resulted in the lowest disease severity ratings throughout the plant. A field trial was conducted to evaluate efficacy of 3 products on Brussels sprouts. Final stalk disease severity in all of the treated plots was statistically less than in the control plot. Disease severity was generally greatest on the lower sprouts of the stalks. Percent diseased sprouts was statistically less in all treatments compared to the control plots. Plant Disease Management Reports for 2011 were published in 2012 and reports for 2012 were submitted for publication. All information was shared with farmers and extension field staff in newsletters and roundtable discussions. Results of the 2012 trials were presented on December 4, to cabbage producers, processors and extension specialists at the annual meeting of the Cabbage Research and Development Board, and will be presented at the Empire State Producers Expo in January 2013. PARTICIPANTS: The individuals who worked on the project included Helene Dillard, Professor of Plant Pathology & Plant-Microbe Biology; Joi Strauss, Technician; Alissa Carissimi, Technician; Susan Scheufele, graduate student. Collaborators included Julie Kikkert, Cornell Cooperative Extension; Christy Hoepting, Cornell Cooperative Extension; Christine Smart, Professor of Plant Pathology & Plant-Microbe Biology. TARGET AUDIENCES: Target audiences include vegetable farmers, private consultants, Cooperative Extension specialists and field staff, fungicide companies, vegetable fresh cut processors, seed companies, and canning/processing companies. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
As a result of this project, growers have a clear characterization of the species of Alternaria on the crucifers grown in NY. This research has shown that in New York the dominant species on crucifers is Alternaria brassicicola. Growers now have greater knowledge about the biology of the fungus and can better understand how Alternaria leaf spot develops in crucifer fields. Greenhouse studies have shown that there is some variation in pathogenicity and fungicide sensitivity amongst the isolates across the state. This helps to explain the variation in disease control experienced by growers. The information has spurred additional conversations concerning management of resistance and fungicide insensitivity. Growers are more aware of the need to manage fungicide usage so that fungicides remain efficacious for many years. Air sampling with rotorod spore traps was used successfully to capture and characterize wind-dispersed spores of Alternaria brassicicola within a field. This information will be very useful in developing recommendations for disease control. Growers will have additional knowledge as to when the appropriate time has been reached to apply protectant fungicides. The new knowledge adds to the knowledge regarding optimal spray timing based on weather conditions. Information from the biocontrol and fungicide studies provides growers with updated fungicide efficacy information and disease control recommendations relevant to the crop and their location. Through our dissemination efforts, growers will have a better understanding of the biology behind Alternaria leaf spot, and will have clear recommendations for disease control using the newer chemistry fungicides.
Publications
- Strauss, J.A., Carissimi, A.M., and Dillard, H.R. 2012. Evaluation of fungicides for control of Alternaria leaf spot in cauliflower, 2011. Plant Disease Management Reports 6:V116.
- Strauss, J.A., Carissimi, A.M., and Dillard, H.R. 2012. Evaluation of fungicides for control of Alternaria leaf spot in cabbage, 2011. Plant Disease Management Reports 6:V117.
- Dillard, H., Strauss, J., Carissimi, A., Kikkert, J., and Hoepting, C. 2012. New Developments in Controlling Alternaria Leaf Spot in Cole Crops. 2012 Empire State Fruit and Vegetable Expo and Becker Forum Proceedings. http://www.hort.cornell.edu/expo/proceedings/2012/Cabbage%20and%20Oth er%20Cole%20Crops/Cole%20crop%20Dillard.pdf
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