2/28/2024 0 Comments Diagnosing tomato late blightLate blight can also develop on green tomato fruit, resulting in large, firm, brown, leathery-appearing lesions, often concentrated on the sides or upper fruit surfaces. On tuber surfaces, lesions appear brown, dry and sunken, while infected tissues immediately beneath the skin appear granular and tan to copper-brown. On potato tubers, late blight appears as a shallow, coppery-brown, dry rot that spreads irregularly from the surface through the outer 1/8-1/2 inch or more of tissue. ![]() Infected areas on stems appear brown to black, and entire vines may be killed in a short time when moist weather persists. In dry weather, infected leaf tissues quickly dry up and the white mold growth disappears. Lesions enlarge rapidly and turn dark brown to purplish-black.ĭuring periods of high humidity and leaf wetness, a cottony, white mold growth is usually visible on lower leaf surfaces at the edges of lesions. The circular or irregular leaf lesions are often surrounded by a pale yellowish-green border that merges with healthy tissue. Late blight appears on potato or tomato leaves as pale-green, water-soaked spots, often beginning at leaf tips or edges. Because infested tomato plants were traced to a garden center chain that has numerous stores across Ohio and the country, diseased plants may have already turned up in peopleââ¬â¢s vegetable gardens. The current outbreak was first reported on tomato plants sold at garden centers and on tomatoes at home gardens and farms in New York, Virginia and Pennsylvania it was also found on potatoes from Pennsylvania. This inoculum can be a threat to commercial tomato and potato producers as well.ââ¬Â ââ¬ÅIf gardeners donââ¬â¢t control it well, a lot of inoculum (spores) may be floating around if weather conditions (cool and wet) favor the disease. ââ¬ÅThis disease is likely to affect a lot of home gardens,ââ¬Â Miller explained. These spores can also be easily dislodged by wind and rain and can be blown into neighboring gardens or fields within five to 10 miles or more, beginning another cycle of disease. Spores formed on the mold are spread readily by irrigation, rain and equipment. Under those conditions, lesions may appear on leaves within three to five days of infection, followed by white mold growth soon after. Late blight thrives under weather conditions such as those that prevailed in most of Ohio this week: nights in the 50s F and days in the 70s F, accompanied by rain, fog or heavy dew, said Sally Miller, a plant pathologist and vegetable crops specialist with the Ohio Agricultural Research and Development Center (OARDC) and Ohio State University Extension. Wayne Ellett Plant and Pest Diagnostic Clinic in Columbus. The disease has been found in only a few gardens in Ohio so far, but the number of inquiries from home gardeners and farmers is starting to increase, said Nancy Taylor, director of Ohio State Universityââ¬â¢s C. If left unmanaged, this disease ââ¬â which is transmitted via spores ââ¬â can result in complete destruction of tomato or potato plants. Responsible for the Irish potato famine of the 1840s, late blight has caused widespread crop damage across the United States and Canada since 1990. This article is part of a monthly series aimed at creating more awareness of the facilityââ¬â¢s state-of-the-art technology and staff expertise by addressing potential horticultural problems for homeowners and garden enthusiasts.ĬOLUMBUS, Ohio ââ¬â Following the confirmation of late blight at an Ohio garden center on June 25 and last weekââ¬â¢s wet, cool weather conditions ââ¬â which create a favorable environment for the spread of the fungal pathogen that causes this potentially devastating disease of tomatoes and potatoes ââ¬â gardeners across the state are now wondering if their backyard crops may be infected and what to do about it. ![]() The clinic is located on the campus of the College of Food, Agricultural, and Environmental Sciences in Columbus, Ohio. Wayne Ellett Plant and Pest Diagnostic Clinic is a leading diagnostic service that aids in the identification and diagnosis of plant diseases, insects and environmental disorders.
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