Answer: The gray mold fungus overwinters as many minute, irregular, black, fungal bodies (sclerotia) and as dormant mycelia on many kinds of plant debris, such as dead strawberry leaves, stems, and fruit, and even on annual weeds in the strawberry patch and adjoining fence rows. As spring approaches, these sclerotia produce large numbers of microscopic spores (conidia). Wind, splashing water, and human activity spread the conidia throughout the strawberry patch, depositing them on blossoms, stems, young fruit, and leaves. Parts of the strawberry plant may become infected within three hours. Temperatures between 70? to 80?F (21? to 27?C) and free moisture on the foliage from rain, dew, fog, or irrigation are ideal conditions for spore germination and infection. Infections may occur at lower temperatures when plants are wet for longer time periods. The fungus usually attacks through dying, dead, or injured petals, stamens, flower stalks, berry caps, or other plant tissue. Fruit infections commonly originate at the stem end. The Botrytis fungus can penetrate the unbroken skin of the strawberry fruit. One affected berry may contaminate many others in the field or even after fruit has been harvested.
There's nothing you can do at this point to protect this year's fruit but you can use fungicide sprays on your plants early next spring to protect the flowers and fruits from developing gray mold. You'll need to spray every 7-10 days, according to the label directions.
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