![]() ![]() 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). ![]() Harvest tubers when the skin is set and avoid mechanical injury.Symptoms of early blight can occur on the foliage, fruit, and stem at any stage of development.Timely application of crop protection materials.Avoid crop stress caused by drought, insect damage, overirrigation, inadequate nutrient levels.Management of early blight requires an integrated program of cultural and chemical practices to minimize sources of inoculum, crop stress, and reduce disease development. Tuber infection occurs at harvest primarily through cuts, bruises or wounds. If early blight is severe, lesions may also be found on stems and tubers. Plants infected with Verticillium or expressing common mosaic symptoms are particularly susceptible to early blight. Early blight is often more severe as the potato crop ages or if the crop has been under stress of poor nutrition, injury, insect damage, drought, or other types of stress. Several cycles of disease occur within a single growing season. ![]() Early blight is usually found first along margins of fields adjacent to fields planted to potatoes the previous year. The disease progresses rapidly during periods of alternating wet and dry weather. Usually older leaves close to the ground are infected first. Spores are carried primarily by wind and infect potato leaves under favorable conditions of warm temperatures (20-30☌) and heavy dews or rain. In the spring, spores initiate infection. This pathogen overwinters in the field as spores or mycelium on dead leaves and vines, on infected tubers and on weed hosts such as hairy nightshade. The early blight fungus is found in most soils where potatoes are grown, and the disease develops every season. The initial fungicide application should be done before the rows close. Preventative fungicide applications are an effective management practice to control this endemic disease.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |