12/19/2023 0 Comments Early blightHowever, leaf spots may, in advanced stages, expand to kill entire areas of leaf tissue and thus exhibit blight symptoms.īlights are often named after their causative agent. On leaf tissue, symptoms of blight are the initial appearance of lesions which rapidly engulf surrounding tissue. South American leaf blight, caused by the ascomycete Pseudocercospora ulei, also called Microcyclus ulei, ended the cultivation of the rubber tree ( Hevea brasiliensis) in South America.Bur oak blight, caused by the fungal pathogen Tubakia iowensis.Ascochyta species and Alternaria triticina that causes blight in wheat Early blight of potato and tomato, caused by species of the ubiquitous fungal genus Alternaria.Bacterial seedling blight of rice ( Oryza sativa), caused by pathogen Burkholderia plantarii.Bacterial leaf blight of rice, caused by the bacterium Xanthomonas oryzae (Uyeda & Ishiyama) Dowson.Fire blight of pome fruits, caused by the bacterium Erwinia amylovora (Burrill) Winslow et al., is the most severe disease of pear and also is found in apple and raspberry, among others.Citrus blight, caused by an unknown agent, infects all citrus scions.Chestnut blight, caused by the fungus Cryphonectria parasitica (Murrill) Barr, has nearly completely eradicated mature American chestnuts in North America.Southern corn leaf blight, caused by the fungus Cochliobolus heterostrophus (Drechs.) Drechs, anamorph Bipolaris maydis (Nisikado & Miyake) Shoemaker, incited a severe loss of corn in the United States in 1970.Late blight of potato, caused by the water mold Phytophthora infestans (Mont.) de Bary, the disease which led to the Great Irish Famine.Accordingly, many diseases that primarily exhibit this symptom are called blights. For the barley blight, see Bacterial blight (barley).īlight refers to a specific symptom affecting plants in response to infection by a pathogenic organism.īlight is a rapid and complete chlorosis, browning, then death of plant tissues such as leaves, branches, twigs, or floral organs. FAO Plant Protection Bulletin 32:91-94."Bacterial blight" redirects here. Illustrated key for the evaluation of early blight of potatoes. Stevenson, W.R., Loria, R., Franc, G.D., and Weingartner, D.P., Publ. "Compendium of Potato Diseases" 2nd Edition.There are many chemistries effective against foliar early blight such as the EBDCs (mancozebs), chlorothalonils, triphenyltin, strobilurins, and coppers. Cultivars differ in their sensitivity to early blight and independently to tuber blight. At harvest, avoid tuber bruises and allow the skin to set. Vines should be well desiccated before harvest. Also weather conditions that result in alternating wet and dry periods promotes it. Early blight spreads faster when plants are stressed. See Tuber Blight under the Tuber Blemishes section. As storage progresses, the skin lesions enlarge, turn watery with a yellowish decay, and in time the tubers shrivel. Lesions are dry, leathery and brown underneath. Symptoms start as dark, sunken skin surfaces areas with raised borders. The disease that forms in storage due to this spore transfer is referred to as tuber blight. solani can move from the ground or infected vines onto tubers. Spores are spread leaf to leaf and plant to plant by breezes. Stem lesions appear as rectangular or oblong blotches that enlarge and turn necrotic thereby hastening vine death. In severe cases, early blight will also infect the stem, usually in the upper half of the plant. The leaves desiccate and fall (defoliation). Leaf clorosis (yellowing) occurs then cells die (necrosis). Sometimes a yellow edge to the lesions can be seen. As the plant ages, lesions move up the plant infecting younger leaves and, in severe cases, infect the stem.ī) Later as the disease progresses, the leaf spots join forming larger lesions. These lesions occur between the veins and as they grow remain bordered by them thereby getting an angular shape. Lesions appear as round dark spots with concentric rings inside, hence the name target spot. See Panel for more information.Ī) Early symptoms appear on lower, older leaves. To estimate this and determine when plants are susceptible, a predictive model is used based on Physiological Days. The onset of early blight is dependent on the age of the plant as advanced by air temperature. Vine infection can only come from spores floating in the air. Tubers that get exposed to early blight spores during harvest can develop a rot called tuber blight after a few months in storage. Early blight or target spot is caused by Alternaria solani, an opportunistic fungus that attacks older leaves as the plant ages or when the plant is under stress.
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