There are several blights (leaf death) of tomatoes, but early blight caused by the fungus Alternaria solani is the most common, especially during wet springs and summers. Leaves near the bottom of the plant will develop spots and the blight will work its way up the plant. Leaf spots are brown and, if examined closely, have concentric rings resembling a target (bull's eye pattern). Eventually, the lower leaves will die and hang on the plant, shriveled and brown, while upper leaves develop spots. Lesions on stems and fruit are similar to those on leaves.
Plant disease resistant or tolerant varieties. Provide good spacing of plants in the garden, and avoid wetting the leaves when watering. Fungicide sprays applied regularly throughout the season will also be helpful. Fungicides are used to prevent disease and must be applied before spots appear; fungicide sprays will not cure already infected leaves. There are several home garden fungicides available; follow instructions on the fungicide label. Contact your local Extension office for fungicide recommendations.
