Phytophthora fruit rot on cucumber

Phytophthora capsici

In cucumber fields, Phytophthora capsici primarily causes fruit rot and on rare occasions, when the weather is favorable, it can infect cucumber seedlings. Sporangia are formed on infected fruit and have a powdered sugar appearance. Sporulation is favored by rain and warm temperatures. Water management has a high impact on disease development. In the presence of water sporangia can differentiate into swimming zoospores. Surface irrigation water can be a source of zoospore spread. The pathogen has two mating types, A1 and A2, that form a survival thick-walled structure called the oospore when they come into contact. The oospore can overwinter in the soil and persist in infested soil for as long as 10 years. Phytophthora fruit rot affects all cucurbit crops.

Diagnostic Resources

Disease Control Information