and life cycle—Late blight
Late blight occurs commonly in coastal environments and sporadically elsewhere. The fungus inoculum can
originate from seed tubers, cull piles, volunteers, closely related weed hosts such as nightshade, and
adjacent plantings of potatoes or tomatoes that are affected. Late blight can develop and spread rapidly
if inoculum is present and conditions are conducive. High humidity and average temperatures in the range
of 50° to 78° F favor the disease. Air circulation to facilitate the drying of foliage each day is important.
Overhead sprinklers can favor late blight.
may support fungus sporulation