The asexual reproduction stage can take as little as 72 hours to complete its cycle to be ready to sporulate again. Early blight, on the other hand, can survive on dead leaves, and vines, in the soil, as well as infected tubers. Late blight infects young, healthy tissue, especially if it's high in nitrogen. It is a disease that strikes actively growing plants and will actually die in senescing tissue. Early blight, on the other hand, is more severe in senescing tissue, such as older leaves, a dying plant, or a plant that has been injured, is insect, disease or drought stressed, or one suffering from poor nutrition.
Infection occurs in healthy tissue from spores in air or water.
Infection rates are low for each spore but, since there are so many spores, the disease can spread rapidly if conditions are right. Tuber infection occurs when spores are washed down to tubers. It cannot get into mature, intact tuber skin, but can enter through immature tubers, lenticles, eyes and wounds. Cross tuber infection is fairly difficult to accomplish, but can happen. Spores have a flagellum so they can swim down and infect a plant indirectly.