Control of Botrytis Diseases and Poinsettia Scab on Floral Crops Floriculture and Nursery Research Initiative Researchers Meeting. March 24-27, 2003 ARS Project Number: Dr. Mary Hausbeck Department of Plant Pathology Michigan State University

Botrytis cinerea

Botrytis Project Objectives Determine role of environment in the disease cycle of Botrytis. Determine role of environment in the disease cycle of Botrytis. Develop production strategies for preventing and eliminating diseases caused by Botrytis on floriculture hosts. Develop production strategies for preventing and eliminating diseases caused by Botrytis on floriculture hosts. Screen novel agents for potential to control Botrytis.Screen novel agents for potential to control Botrytis.

Reduced Risk and Biopesticides Reduced RiskReduced Risk –BAS 510 –Decree* –Compass* –Heritage* –Cabrio –Actigard* –Switch BiopesticidesBiopesticides –Endorse –Bacillus lichenformis –Bacillus subtilis* –Mycostop* Indicates greenhouse label * Indicates greenhouse label

Rate/100 gal 7-Day Spray Interval

Rate/100 gal 14-day Spray Interval

7-day Rate/100 gal 14-Day Spray Interval

Rate 100/gal 14-Day Spray Interval

Rate/100 gal 7-Day Spray Interval Rate 100/gal 14-Day Spray Interval

7-day Rate/100 gal 14-Day Spray Interval

Untreated Chlorothalonil 32 fl oz

Untreated Endorse 2.2 lbs

UntreatedDecree 24 oz

Summary While industry standards such as chlorothalonil continue to provide excellent disease control, new reduced risk products products such as fenhexamid (Decree) and the strobilurins have been proven to be effective.While industry standards such as chlorothalonil continue to provide excellent disease control, new reduced risk products products such as fenhexamid (Decree) and the strobilurins have been proven to be effective. The biopesticide Endorse has shown potential in controlling Botrytis.The biopesticide Endorse has shown potential in controlling Botrytis.

Poinsettia Scab

Objectives Examine laboratory and greenhouse methods for the successful isolation, culture and inoculation of Sphaceloma poinsettiae.Examine laboratory and greenhouse methods for the successful isolation, culture and inoculation of Sphaceloma poinsettiae. Determine the role of the environment in the infection and spread of Sphaceloma poinsettiae.Determine the role of the environment in the infection and spread of Sphaceloma poinsettiae. Screen traditional and novel fungicides for the management of poinsettia scab.Screen traditional and novel fungicides for the management of poinsettia scab. Screen cultivars for resistance to poinsettia scab.Screen cultivars for resistance to poinsettia scab.

Accomplishments Methods have been found for the successful isolation and culture of Sphaceloma poinsettiae. Inoculum has been used for trials both at MSU and other facilities.Methods have been found for the successful isolation and culture of Sphaceloma poinsettiae. Inoculum has been used for trials both at MSU and other facilities. 57 cultivars have been screened for resistance to poinsettia scab. Although all cultivars have been found to be susceptible, differences were noted in the degree of infection among cultivars.57 cultivars have been screened for resistance to poinsettia scab. Although all cultivars have been found to be susceptible, differences were noted in the degree of infection among cultivars.

Inoculum

Spore Trapping and Environmental Monitoring

Potential Value for Stakeholders and Technology Transfer Information on the efficacy of fungicides and the environmental parameters that promote infection will help in the development of effective management tools for the industry.Information on the efficacy of fungicides and the environmental parameters that promote infection will help in the development of effective management tools for the industry. Information will be disseminated through grower talks and publication in trade magazines and professional journals.Information will be disseminated through grower talks and publication in trade magazines and professional journals.

Contributors to Research Jeffrey WoodworthJeffrey Woodworth Blair HarlanBlair Harlan Brian CortrightBrian Cortright Sheila LindermanSheila Linderman Nicholas WendlingNicholas Wendling Nicole WernerNicole Werner Bill QuackenbushBill Quackenbush Amanda GevensAmanda Gevens Project Team Dr. Mary Hausbeck - Michigan State University - Michigan State University Dr. Steve Wraight Dr. Steve Wraight - Cornell University, USDA-ARS - Cornell University, USDA-ARS

Funding Sources American Floral Endowment.American Floral Endowment. – ‘Fighting Foliar Diseases Using Tools: Forcasters and Environmentally Friendly Fungicides.’ $96,000. Botrytis, Powdery mildew, Downy mildewBotrytis, Powdery mildew, Downy mildew IR-4 ornamental trials on Botrytis.IR-4 ornamental trials on Botrytis. –2002. $2,000