Symptoms are commonly referred to as cotton root disease, rot, and lumbar fold disease. The main damage cotton seedlings. At the base of the infested young stems and stems, the vertical brown stripes are quickly spread around the stems for a week, shrinking, and appearing stem-root rot or root rot. Cotton seedlings lose water faster and generally do not fall flat. Dead seedlings are easily pulled out of the soil, and sparse filaments and small soil particles adhering to them are visible on the base or roots. Infected seeds caused rotten or rotten buds. The diseased seeds were brown soft and rot-like, and the total yellow-brown mucus came out when squeezed. Invasive cotyledons and young form an irregular brown necrotic spot, followed by dry perforation. When the humidity is high, sparse white mycelium is visible in the diseased part, and a brown sclerotia adheres to it.
The pathogen Rizoctomia solani Khn AG-4 is known to evaluate the hyphae of the Rhizoctonia solani AG-4 mycelial fusion group, which is a fungus of the subphylum Fungi. It has been reported that a small number of fusions such as AG-5 and AG-1-IA can also infect and cause diseases, but they do not cause dead seedlings. AG-4 has a wide host and strong pathogenicity. In addition to invading cotton, it also infects rice, wheat, corn, peanuts, and sesame seeds. The experiment inoculated Rhizoctonia solani and Rhizoctonia solani on wheat and cotton seedlings, and did not infect each other. Therefore, the relationship between AG-4 on other hosts and cotton seedlings needs to be further clarified. The strain has the sexual state of Thanatephorus cucumeris (Frank) Donk called melon-degrading bacteria and is a basidiomycotina fungus.
Transmission routes and pathogenic conditions The main pathogenic bacteria are mycelia and sclerotium that live in soil or on sicknesses. They rarely thrive on the mycelia and latent in the seeds. However, when the cotton bolls are infected before the flower is collected, the bacteria invade. The inside of the bell caused the seed to become a source of infestation in the early years. In the cotton field, the top soil layer, which is mostly concentrated within 6cm, can survive for 2-3 years. When the pathogen meets the appropriate conditions and host, mycelium attaches to host epidermal cells to form infestation mats, then invade the cells with outstretched lines. It can also invade from wounds and natural orifices. Mycelium expansion leads to tissue necrosis and browning. Cortical weaves are filled with mycelia and sclerotia as an important re-infestation source. The germs are transmitted by flowing water, underground pests and agricultural operations. Rainy and damp weather is good for blight. In addition, the production of low-lying or soil viscous cotton field easy to disease; sowing too early, low soil temperature, seedling growth is slow and bad disease incidence of poor drainage.
Control methods (1) selection of disease-resistant varieties. Such as Jinmian No. 16 (Shimian No. 5), Jinmian No. 21 and so on. A large area of ​​rational rotation. (2) Advocate the use of composted compost or decomposed organic fertilizer and 5406 fungus fertilizer. Fine soil preparation improves the quality of sowing. (3) Select cotton seeds before sowing, and use 50% carbendazim wettable powder or seed reseeding with a seed weight of 0.5%-0.8%. (4) Promoting the use of de-velvet coated cotton seeds, which can increase the incidence by 3-4 days in advance. (5) Suitable for early sowing, spring cotton should be sown at a depth of 5cm at 14°C and sown at a depth of 4-5cm. (6) Strengthen seedling management, appropriate early morning seedlings, timely early cultivating, pay attention to reduce soil moisture, increase ground temperature, cultivate strong seedlings, pay attention to drainage after rain, and prevent moisture retention. (7) After the onset of the disease, the roots were irrigated with 80% tuzet or 20% pod wettable powder 1000 times, or 25% carbendazim wettable powder 500 times sprayed 2-3 Times.
The pathogen Rizoctomia solani Khn AG-4 is known to evaluate the hyphae of the Rhizoctonia solani AG-4 mycelial fusion group, which is a fungus of the subphylum Fungi. It has been reported that a small number of fusions such as AG-5 and AG-1-IA can also infect and cause diseases, but they do not cause dead seedlings. AG-4 has a wide host and strong pathogenicity. In addition to invading cotton, it also infects rice, wheat, corn, peanuts, and sesame seeds. The experiment inoculated Rhizoctonia solani and Rhizoctonia solani on wheat and cotton seedlings, and did not infect each other. Therefore, the relationship between AG-4 on other hosts and cotton seedlings needs to be further clarified. The strain has the sexual state of Thanatephorus cucumeris (Frank) Donk called melon-degrading bacteria and is a basidiomycotina fungus.
Transmission routes and pathogenic conditions The main pathogenic bacteria are mycelia and sclerotium that live in soil or on sicknesses. They rarely thrive on the mycelia and latent in the seeds. However, when the cotton bolls are infected before the flower is collected, the bacteria invade. The inside of the bell caused the seed to become a source of infestation in the early years. In the cotton field, the top soil layer, which is mostly concentrated within 6cm, can survive for 2-3 years. When the pathogen meets the appropriate conditions and host, mycelium attaches to host epidermal cells to form infestation mats, then invade the cells with outstretched lines. It can also invade from wounds and natural orifices. Mycelium expansion leads to tissue necrosis and browning. Cortical weaves are filled with mycelia and sclerotia as an important re-infestation source. The germs are transmitted by flowing water, underground pests and agricultural operations. Rainy and damp weather is good for blight. In addition, the production of low-lying or soil viscous cotton field easy to disease; sowing too early, low soil temperature, seedling growth is slow and bad disease incidence of poor drainage.
Control methods (1) selection of disease-resistant varieties. Such as Jinmian No. 16 (Shimian No. 5), Jinmian No. 21 and so on. A large area of ​​rational rotation. (2) Advocate the use of composted compost or decomposed organic fertilizer and 5406 fungus fertilizer. Fine soil preparation improves the quality of sowing. (3) Select cotton seeds before sowing, and use 50% carbendazim wettable powder or seed reseeding with a seed weight of 0.5%-0.8%. (4) Promoting the use of de-velvet coated cotton seeds, which can increase the incidence by 3-4 days in advance. (5) Suitable for early sowing, spring cotton should be sown at a depth of 5cm at 14°C and sown at a depth of 4-5cm. (6) Strengthen seedling management, appropriate early morning seedlings, timely early cultivating, pay attention to reduce soil moisture, increase ground temperature, cultivate strong seedlings, pay attention to drainage after rain, and prevent moisture retention. (7) After the onset of the disease, the roots were irrigated with 80% tuzet or 20% pod wettable powder 1000 times, or 25% carbendazim wettable powder 500 times sprayed 2-3 Times.