Phytophthora blight, caused by Phytophthora capsici, is the most important disease of cucurbits and peppers in Illinois. In wet conditions, the disease may cause 100% crop losses. Following the recent heavy rainfalls, the disease developed in our pumpkin plots near South Pekin in Tazewell County. Processing pumpkin fields in the area are being sprayed to protect plants against the pathogen. In the past, this disease has been observed in most of vegetable growing areas in Illinois. The following practices are recommended for managing the diseases in cucurbit and pepper fields:

• Check your field for development of the disease. Phytophthora blight develops first in the low area (where the soil stays wet longer). Remove the infected plant(s) from the spot and take away from the field.
• Keep the soil as dry as possible.
• Spray plants at the first sign of the disease in your field with the following fungicides: Revus + Reliant alternates with Ranman + Reliant at 7-day intervals. Reliant is a phosphorus acid-based (phosphonate) fungicide. There are other commercial compounds with the same active ingredient of Reliant (i.e., ProPhyt) and you can use any of them in place of Reliant. 
• Learn more of Phytophthora blight on cucurbits and peppers.

Image: Pumpkin vine infection by P.capsici. Photo by Babadoost

Author: Mohammad Babadoost, professor and faculty Extension specialist
Dr. Babadoost develops solutions for vegetable and fruit crop diseases. He is internationally renowned for identifying effective disease management strategies for cucurbits, tomatoes, peppers, horseradish, basil, and apples. He also educates scientists in developing countries to improve production and quality of food crops. His Extension program emphasizes outreach education and integrated management of vegetable and fruit crops. Problem solving is the main goal of his Extension program. He provides disease management information to vegetable and fruit growers using technologies that range from very old fashion, but accurate, to web delivery. He participates in winter schools, conducts field demonstration programs, and provides references in order to educate the growers on identification of diseases, understand disease characteristics, and benefits of IPM practices in disease management.