This is a nice healthy tomato plant, one that Meg McGrath, an associate professor of plant pathology at Cornell, no doubt would wish for all of us. McGrath, an expert on late blight, suggested recently that the soggy spring of 2011 has folks once again wondering about - read fearing - this highly destructive disease that spread throughout the northeastern United States in 2009, destroying whole tomato and potato crops on farms, in addition to plants in many backyard gardens.
Late blight is, for lack of a better word, challenging, she says. For one thing, it cannot be "lived with" or managed. If your plants show signs of having it, they must be destroyed immediately - not composted, but burned or disposed of in the trash. Otherwise, the whole crop/garden goes down.
Symptoms include brown spots or lesions on the stems, with white fungal growth, causing the stems to soften, then collapse.
You'll also see brownish spots about the size of a nickel on the leaves and firm brown spots on the tomatoes.