Phytophthora blight was diagnosed last week in pepper plants from Huron County, Ohio. This is several weeks earlier than we normally see Phytophthora blight in northern Ohio, but heavy rains and periods of high temperatures likely contributed to an early appearance of the disease. Growers should scout both peppers and cucurbits for typical symptoms of Phytophthora blight.
Phytophthora is a water mold that thrives under conditions of high moisture and high temperature. It produces motile spores (zoospores) that are attracted to plants, then form a structure that allows them to infect, and aggressively attack any type of plant tissue. Zoospores can be splashed onto leaves, stems and fruits during rain events and overhead irrigation. Phytophthora blight is often seen first in low spots or other poorly drained areas of production fields, but the disease also occurs on well-drained, even sandy soils if the environmental conditions are right. An integrated, preventative program to manage Phytophthora blight is more effective than in-season rescue treatments with fungicides. During the growing season, fungicide application is the main option for management of Phytophthora blight. In small plantings prompt removal of diseased plants is also recommended.