Irregular patches of rot on leaves; white cottony growth with spores on undersides. Storage of potato tubers in cold storage rooms reduces or even checks the progress of the rot. by zoospore formation. In advanced stages of late blight, leaf All volunteer potato plants in the area (whether in the potato or other fields) should be destroyed, because any volunteer potato plant may be the source of infection. The severity of late blight infection is governed by environmental conditions. November 12. The sporangium functions as a conidium (Fa). Phytophthora infestans, the pathogen of potato late blight which is a devastating disease of potatoes, causes stem and leaf rot, leading to significant economic losses. The released zoospores, after a brief period of activity in rain water or dew come to rest. These are carried by wind to the healthy plants which are thus infected. What is Potato Late Blight? Resistance alone has not effectively checked the disease. ADVERTISEMENTS: In this article we will discuss about the late blight of potato caused by fungi. Late blight lesion on a potato leaf.Gray or brown lesions surrounded by a light green (chlorotic) area are very characteristic of late blight.Lesions that look like this are about one week old. Potato dumps or cull piles should be burned before planting time or sprayed with strong herbicides to kill all sprouts or green growth. Growing these will provide an increasing opportunity to combat the disease. Necessary cookies are absolutely essential for the website to function properly. In cool and dry conditions the progress of the disease is slower and the wet rot phase is generally checked. They play a significant role as the source of primary infection. 7. Save my name, email, and website in this browser for the next time I comment. Potatoes infected with late blight are shrunken on the outside, corky and rotted inside They also stink and once smelt, never forgotten. These are applied before infection for effective control in two ways namely by spraying or dusting as follows:-. In case you were wondering, late blight is the plant disease that is responsible for the famous Irish potato famine of 1845. Mistiming of sprays may have serious consequences for late blight control in N.E.U.S.A. The sexual phase seems to play no significant role in the life history of the pathogen. Late blight of potatoes can be controlled successfully by the following methods : Your email address will not be published. Each retracts its flagella and secretes a wall around it. After infection they grow best at a slightly higher temperature. It is caused by zoospores produced in foliage lesions (blighted tops) or present in the contaminated soil. /TASS/. Finally, a rapid and general blighting of foliage occurs. This requires strict seed tuber inspection at the cutting time. It is mandatory to procure user consent prior to running these cookies on your website. On the leaf underside, a spore-producing zone of white moldy growth approximately 0.1 - 0.2 inches wide may appear at the border of the lesion. It can infect and destroy the leaves, stems, fruits, and tubers of potato and tomato plants, and has been known to infect other plants of the Solanaceae family as well. Oomycetes are fungus-like organisms also called water molds, but they are not true fungi. The tubers get separate infections (G). The scientific name of late blight is Phytophthora infestans, appropriately named for its terrible habits. The persistence of the fungus in the soil is out of the question because the temperature during summer becomes very high. The longer the zoospores continue to swim and greater their number, the greater are the chances of infection. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. it also attacks potato tubers in the field. often a pale yellowish-green zone surrounds the rapidly enlarging lesions. Only the resistant varieties available i.e. Symptoms on Leaves 1) Late Blight appears on potato or tomato leaves as pale green, water soaked spots often beginning at … The famous Irish famine in 1845-1846 was caused due to the destruction of the potato crop by late blight disease. The disease occurs annually in the cooler Himalayan regions extending from Assam to Kashmir at an altitude of 6,000 ft. or more as the crop is grown in the rainy season. Under continuously moist conditions, all tender and above-ground plant parts blight and rot away quickly giving off a characteristic odor. Potato or tomato plants that are infected may rot within two weeks. De Bruyn (1926) opined that the fungus overwinters in the soil but this remains unconfirmed. The symptom appears first on the leaves as black or purplish-black circular or irregular water-soaked patches, generally at the tips or edges of the lower leaves. Diagram 3. The key difference between early blight and late blight of potato is that early blight of potato is a disease caused mainly by the fungus Alternaria solani while late blight of potato is a disease caused by the oomycete Phytophthora infestans.. Therefore primary inoculum of the disease in the field comes from the planting of infected seed tubers and from oospores in the previous year’s plant debris, the pathogen next invades developing sprouts to form lesions and sporangia or zoospores above ground. In severe cases of infection there is complete loss of the crop, Infection also results in the decay of tubers in the field and storage. An important disease.