R Resistance to this group of fungicides has been reported in North Carolina. For the latest fungicide recommendations for early blight, consult the Southeastern US Vegetable Crop Handbook.Įxample products for control of early blight in tomato. In general, apply on a 7-14 day interval except where the label specifies otherwise. In addition to the cultural practices listed above, there are several products that are effective at controlling the disease. In general, bacterial spot will be smaller (~1/16 in), may be water-soaked on the underside of the leaf, and the center of the lesion may fall out.ĭisease Control for Conventional Growers Skip to Disease Control for Conventional Growers Bacterial spot also may be confused with early blight when the early blight lesions are young and small or when both are present. Late blight will occur all over the plant including young leaves, whereas early blight would be found primarily on the lower leaves. Late blight produces lighter tan colored lesions that typically have a light green halo. Also, most hybrid tomatoes have resistance to gray leaf spot however, most, if not all, heirloom varieties lack this resistance. Gray leaf spot also produces smaller and lighter brown lesions than what you would see with early blight, and the center of the gray leaf spot lesions tend to crack. Septoria leaf spot produces smaller lesions with tan or light gray centers.
Look alike diseases: Several fungal diseases occur on the foliage of tomato and can make identification difficult. Spores may be abundant on lesions on any part of the plant. Lesions can expand to cover the entire fruit and are typically sunken, leathery, and dark brown to black with concentric rings. In later stages, lesions may appear in the upper leaves and defoliation may occur in the lower part of the plant leaving the fruit susceptible to sunscald.įruit may become infected through the calyx around the stem attachment and are susceptible in the green or red stage. The area surrounding the lesions may become yellow and, as disease progresses, the entire leaf may turn yellow. Lesions first develop on lower leaves as small, brownish-black spots which can expand to about 1⁄ 4 - 1⁄ 2-inch in diameter with characteristic concentric rings in the darkened area.
The disease is more commonly observed in the field, however, seedlings in the greenhouse can be affected by collar rot (also caused by species of Alternaria). Symptoms of early blight can occur on the foliage, fruit, and stem at any stage of development.
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