Regrowth after hail may extend the flowering period, which also increases the sclerotinia stem rot risk. When hail hits at late flowering, broken stems and leaves along with lodging can further increase the sclerotinia risk due to the fungus growing from plant to plant directly. But should a grower automatically spray fungicide on a hailed crop? That depends. If yield potential is still high and if conditions favorable to sclerotinia stem rot persist, then a fungicide spray may pay off.
Hail and other diseases: Hail wounds on the plant can provide points of entry for alternaria black spot or blackleg if environmental conditions have been conducive to spore production and disease development.