Symptoms mainly occur on the roots of tobacco plants, causing the roots to appear black rot specifically, and can develop from seedlings to adult plants. Miao disease causes "fallen", but the roots are darkened, which is different from damping-off. The pathogens invade from the rhizomes, and the lesions surround the stems for a week, invading the leaves up and down to the lateral roots, causing the entire seedlings to die. The root tip of the lateral roots of the larger infected plants became black, the growth of the diseased plants was sluggish, the plants were short, and the leaves were yellow-brown. The roots of the whole plant became dark brown and necrotic with the severely ill strains uprooted. When the climate is hot, the diseased plants will wilt during the day and return to normal at night. The leaves of the diseased plants will turn yellow and thin, which will seriously affect the yield and quality of tobacco. There are two kinds of spores: one is endospores, which is produced from spores, long rods, and colorless. The end cells of the endospore stalk are slender, reaching 80 to 170 um. After the conidia in the stalk have matured, new conidia continue to form behind them. The dark golden brown gold is smooth and the size is 10 to 177 to 12 (um). . The conidia were emitted in a string through the top projection tube of the conidiophore. Another species is the chlamydosporum clavatum, multicellular, basal l-3 cells are colorless and transparent, the upper 4-5 cells are brown, the ends are semi-circular, the middle cell is square, and when mature, it splits into single cells. Germination alone, the size of the chlamydospore 34-6811-13(um). Transmission routes and disease conditions The diseased and colonized soils are the primary sources of infestation of the disease. Under suitable conditions, conidiospores or cysts germinate to produce invading filaments that invade the host epidermal cells from the wound. After invading, the hyphae spread and spread in the epidermal cells. A large number of conidia and chlamydospores of the form A are reinfected. The onset of the disease temperature is 17-23 °C, less than 15 °C or 26 °C lighter. Relative humidity is above 80% when the disease becomes severe. It is easy to cause epidemic with low temperature and rain or even rainy days. The pathogen can infect families, legumes, cucurbits and other 30 families with more than 120 kinds of plants, and these plants are associated with severe disease. Low-lying wetlands and infertile saline-alkali lands are easy to develop. Control methods (1) Selection of resistant varieties currently selected include Nc2, Nc88, Nc89, Nc95, Nc98, Japan's Shanyang 1, Yuanzhou 1, Maryland 609, Burley, Burley 2, etc. Built-in white 80, 8701, 8301, B37, ribs 11A, 11B, 21B, 37B, 49B, and the like. (2) Implement crop rotation and grass crops for more than three years to avoid cropping with leguminous and vegetable crops. (3) Strengthen cultivation and management, use disease-free seedbeds when growing seedlings, and do not apply organic fertilizer with pathogens. Pay attention to the humidity in the field and timely cultivating loose soil. (4) Chemical control The bed soil was sterilized with 10 g/m2 of 50% thiophanate-methyl or 50% phenylenediamine wettable powder. When planting, use the above agent 50g/667m2 mixed soil after acupuncture. In the initial stage of disease, water 50% thiophanate-methyl WP or 50% carbendazim WP 600-800 times, 50% DM WP 500-fold, each with a good solution. 200ml. Lactobacillus Rhamnosus,Lactobacillus Rhamnosus Powder,Lactobacillus Rhamnosus Probiotic,Lactobacillus Rhamnosus Supplement Jiangsu Biodep Biotechnology Co. ,Ltd. , https://www.mbioda.com
The pathogen Thielaviopsis basicola (Brek. et Br.) is called a genus genus, and is a fungus of the subphylum Fungi. Hyphae initially colorless, after the brown, diameter 3-7um, with a separation. Conidiophore 506-9 (um), solitary or clustered.
Tobacco root black rot