Sweet Potatoes

Disease Control


 Black Rot and Scurf.
Avoid bruising roots during harvest. Maintain a temperature of 80 to 85°F (26.7 to 29.4°C) during the curing period, and do NOT allow temperature during storage to drop below 55°F (12.8°C). Maintain a relative humidity of 85 to 90 percent during curing and storage.
Seedbed soil should be new or sterilized sand, and a bed temperature of 80 to 85°F (26.7 to 29.4°C) should be maintained. Use a 2-year rotation as an aid to control all field diseases. Avoid applying fertilizer after July 1.
Use seed potatoes that are free of scurf for sprout production. During bedding, dip "seed roots" for 1-2 minutes in a suspension containing 8 fluid ounces of Mertect 34OF per 7.5 gallons of water and plant immediately.
Use sprouts that are cut above the soil line whenever possible to reduce incidence of scurf.

 Soft Rot (Rhizopus).
Use a disease resistant variety (eg. Beauregard)

At harvest: Dip or spray harvested table or seed-stock potatoes after cleaning and before packaging. Use 1 pound of Botran 75WP in 100 gallons of treating solution.
During bedding: Just before bedding, use a 10- to 15-second root dip. Use Botran 75WP (1 pound per 10 gallons of water).

 Pox (Soil Rot).
Maintain a pH between 4.8 and 5.2 to assist in control. Use crop rotation, clean seed, and clean beds.

 Fusarium Wilt.
Use resistant varieties.

 Surface Rot.
Minimize injury during harvest. Cure as soon as possible under proper storage conditions. Use clean seed for bedding.

Information provided is intended for consideration by the user, but is not intended to be a recommendation. Production decisions should be based on consideration of many types of information (scientific, experiential, economic, legal, etc.) available to the user.

Where trade names are used no discrimination is intended, and no endorsement by the Cooperative Extension Service is implied.

 Dr. Alan A. MacNab, Professor, Plant Pathology
Penn State College of Agricultural Sciences
211 Buckhout Lab, University Park, PA 16802

Updated: Nov, 2005; EMH
Loaded: Nov, 2005; EMH

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