Hermiston Agricultural

Research & Extension Center

2121 South First Street

P O Box 105

Hermiston, OR 97838-0105

Phone (541) 567-8321 Fax (541) 567-2240

Oregon State University Extension Service offers education programs, activities, and materials--without regard to race, color, religion, sex, sexual orientation, national origin, age, marital status, disability, and disabled veteran or Vietnam-era veteran status--as required by Title VI of the Civil Rights Act of 1964, Title IX of the Education Amendments of 1972, and Section 504 of the Rehabilitation Act of 1973.

Oregon State University Extension Service is an Equal Opportunity Employer.

June 6, 2002

Memorandum

To: All Fieldmen and Area Potato Growers

From: Phil Hamm, Extension Plant Pathologist

RE: Late Blight

Late Blight has been confirmed outside of Burbank WA. The weather has been wet at times and certainly mild, both of which favors this disease.

I would suggest that all fields be treated with a protectant fungicide at or about row closure and repeat applications every 7 days until the end of the month. We must do everything possible to reduce the chances of this disease getting established early in this growing season.

I would suggest that air application is the best but to save application costs, begin with an air application and then follow by applying by chemigation. Follow this rotation of methods until the end of the month.

Use an EBDC or Chlorothalonil if only protecting for late blight. There may be some cost savings by applying Omega for both late blight and white mold control, depending on the status of a particular field.

If you have questions, please give me a call or call the Late Blight Hot Line for updates as available (1-800-705-3377).