Seasonal development
and life cycle—Bunch rot
 Following injury, berries are susceptible to invasion by many microorganisms that frequently enter through
insect- or bird-feeding sites, mechanical cracks, or lesions. The Botrytis fungus that causes bunch rot
survives in decaying plant material in or on the soil and as sclerotia. It usually infects only flowers
and senescing or injured tissue, especially plant parts in contact with damp soil. However, green, healthy
tissue may be affected. Grapes are infected at the flower stage, but the fungus remains dormant until
fruit mature; bunch rot then develops if conditions become cool and damp.
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