Edward J. Sikora, Extension Plant Pathologist, Associate Professor, Plant Pathology Plant Disease Notes Gray Mold of Strawberries Gray mold, caused by the fungus Botrytis cinerea, is a common and serious problem wherever strawberries are grown. The fungus is widespread and is often found in new plantings. The disease is named for the grayish brown spores that cover the surface of lesions on the fruit.
Infections first occur on fruit tissue under the calyx.
Fruit infections appear as soft, light brown, rapidly expanding spots. Both green and red fruit are susceptible to infection, but ripening fruit rots faster. Persistence And Transmission. Early season temperatures between 70 and 80 degrees F and wet weather are ideal for disease development. Infection can also occur at lower temperatures when the plants are wet for extended periods.