6/13/2023 0 Comments Late blight of potatoThe main places of tuber infection are, eyes, lenticels, and wounds. Germination of zoospores occurs frequently in susceptible varieties. The infection by sporangia or zoospores take place at any part of the epidermis of leaves and stem, especially young stems. These fungus produce spores which infect lower leaves in contact with the soil. Fungus may also develop from the tuber in soil. The mycelium from the infected parent tuber grows upward in the stem and sporulates on the shoots. The mycelium in these infected seed tubers serves as the source of primary inoculum. Infected tubers left in the field carry over the living mycelium to the next crop season. High temperature and drought kill the fungus in soil. Optimum soil moisture is 15 to 20% saturation stage. The viability of sporangia in soil depends on moisture and temperature. Rainfall during the next 24 hours of at least 0.1 mm. Night temperature below dew point for at least 4 hour. Maximum outbreak of the disease happens when conditions are favorable for germination of sporangia by zoospores.Īlso read: Important questions on vegetable science (6). infestans has a large number of races differing in pathogenicity to host genotypes. The ideal temperature for the formation of oospores is 23☌. After few minutes, the zoospores germinate by a tube which penetrates the epidermis of the host directly or through stomata. High temperature (24☌ or above) favours the formation of sporangium. Low temperature favours the formation of zoospores. The method of germination of sporangia is governed by temperature. The sporangium first develops at the tip of a branch. In moist atmosphere, white tufts of mycelium and sporangiophores of the fungus appear on the surface of the tuber in the stores.Heavy infestation causes rotting of tubers.Latter, it turns into a brownish dry rot, which is about a half an inch below the surface.The first sign of tube infection is a brown to purple discoloration of the skin.In cool moist weather, the pathogen becomes active and corresponding symptoms, and progress reappear. This whitish area consists of the aerial fructification of the pathogen. On the lower side of the leaf apposite to this zone a mildew growth appears which is whitish or grayish. A zone outside the purplish lession shows a paler than normal green merging into the latter. Dry condition may cause the curling of leaves with hard leaf surface.Īlso read: Olericulture (Vegetable Science) MCQ (Multiple Choice Questions) (3). Moist condition deteriorates the leaves very soon. Dead areas appears at the tip of leaf or the margin, from where it spread downward and inward. At first, this will look like chlorotic, then it turns brownish black. Presence of brown dead spots on leaves, and presence of the extended dead areas on leaves. 1943: Meerut district of Uttar Pradesh, and Dehradun district of Uttarakhand.1912 to 1913: Severe attack in Jorhat district of Assam.1889 to 1900: Third appearance, Hoogly district of West Bengal.After 1880: Second appearance, Darjeeling district of Himalayas.1870 to 1880: First appearance, Nilgiri hills of South India.Cause of the disease (causal organism)Īlso read: What is Seed Plot Technique in Potato? (1). Characteristic symptoms or of late blight of potato Host: Potato and tomato are the two main host of this disease. Timely and proper control, and management of the disease is very necessary and important to avoid heavy loss. If the conditions are favorable, then no other disease can be as destructive and dangerous as late blight. Late blight of potato is one of the most destructive among all the potato diseases. Late blight of potato and its management (control) What is late blight of potato?
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