Cotton cotton anthracnose

Symptoms can be diseased at seedling stage and adult stage. The emergence of seedling disease after germination before emergence can cause bad species; after the emergence of the stem base red-brown stretch streak, expand contracture caused by seedling death. An orange-orange viscous (disease conidium) was produced on the lesion when wet. A round or semi-circular melasma appears on the edge of the cotyledon, and the cotyledon edge is incomplete after drying and shedding. In the early stage of the infection, the bolls showed dark red spots, brown lesions after expansion, and diseased depressions. There were orange-red powders, which were conidiospores. When it is severe, the whole bell rots and cannot crack, and the fibers turn black. Leaf lesions irregularly rounded, easy to dry and crack. Stem lesions red-brown to dark black, oblong, central depression, epidermal rupture often exposed xylem, the wind is easy to fold. Late in the production, cotton bolls suffered heavy losses and suffered heavy losses.


The pathogen, Colletotrichum gossypii Southw., called cotton anthrax, belongs to the fungus Aspergillus spp. The sexual state is Glomerella gossypii (Southw.) Edgerton said that the small hull of cotton is an ascomycete-like fungus that is rare. The ascostic shells are dark brown, spherical to pear-shaped, 100-16080-120 (μm) in size, and are buried within the host's binding. Ascospores contain 8 ascospores, single cells, oval, slightly curved, size 12-205-8 (μm). The asexual conidia were born on conidiophores and arranged in shallow basins. The conidium discs were bristly, bristly dark brown and had 2-5 septa. Conidiophores are shorter and conidiospores can be produced continuously. Conidia are colorless, single-celled, long-elliptic or short-stick, size 9-263.5-7 (μm), most connate, pink. Conidial germination often produces 1-2 septa, one sprout tube at a time, and an attachment to the tip of the sprout tube, invading the wire and invading the host. Conidial germination temperature 25-30 °C, 35 °C germination less growth slow, 10 °C does not germinate. Suitable for the onset of soil temperature is 24-28 °C, relative humidity more than 85%.
Transmission routes and pathogenic conditions The pathogens mainly overwintered with conidiospores on cottonseed linters, and a small part of the pathogens latent on the seed coats of cottonseeds or cotyledons through the winter. Seed carrier was an important primary infestation source. The conidia of pathogenic bacteria can survive for 1-3 years on cottonseeds. Because the initial temperature of germination of cottonseed and the initial temperature of spore germination are all around 10°C, the germinating of cottonseeds is very easy to invade. Afterwards, the diseased parts produce conidia by wind and rain, insects and Irrigation water spreads. Boll bacterial infections invade cottonseeds, with a bacterial infection rate of 30%-80%. The diseased leaves, stems, and bells fall into the soil and cause soil contamination, which can trigger the onset of disease at the seedling stage, and can also cause the cotton bolls to be infested by rain splashes and cause boll attacks.
The selection of disease-free seeds and seed disinfection for prevention and control are the two keys to prevent and treat this disease. (1) Use good quality disease-free seeds or seeds every other year. (2) Seed treatment before sowing. With 40% of the seed dressing double wettable powder 0.5kg and 100kg cotton seed dressing; also can use 70% thiophanate-methyl wettable powder 0.5kg and 100kg cottonseed seed dressing; also can use 70% wood MnZn wettable powder 0.5 Kg and 100kg cotton seed dressing, in addition can also be used 1kg 10% Lingfu mixture and 50kg cottonseed coating, have better control effect. (3) Suitable sowing, cultivating strong seedlings, promoting the early development of cotton seedlings, and improving disease resistance. (4) Rational close planting reduces the humidity in the field, prevents overgrowth of the cotton seedlings, and pays attention to preventing premature aging of the bell. (5) Spray 70% thiophanate-methyl (thiophanate-methyl) WP 800 times or 70% chlorothalonil wettable powder 600-800 times, 70% Mancozeb WP -600 times liquid, 50% benomyl WP 1500 times, 25% Carbonate wettable powder 500 times.