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Control methods for diseases, pests and weeds during the cotton sowing period and seedling stage

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This year, affected by abnormal climate, the cotton sowing time in our province was delayed. Under this continuous low-temperature condition, cotton growth and development were delayed, and the degree of disease and pest damage was relatively aggravated. For this reason, the situation facing cotton disease and pest control this year is more severe. From the start of sowing, every key control technique must be firmly implemented, especially the links in pesticide selection and use. The main disease and pest control techniques for the sowing period and seedling stage are introduced to the broad community of farmers as follows: 1. Strictly control the seed treatment with pesticides at the sowing stage. Before cotton sowing, focus on

This year, affected by abnormal climate, the cotton sowing time in our province was delayed. Under this continuous low-temperature condition, cotton growth and development were delayed, and the degree of disease and pest damage was relatively aggravated. For this reason, the situation facing cotton disease and pest control this year is more severe. From the start of sowing, every key control technique must be firmly implemented, especially the links in pesticide selection and use. The main disease and pest control techniques for the sowing period and seedling stage are introduced to the broad community of farmers as follows:

1. Strictly control the seed treatment with pesticides at the sowing stage. Before cotton sowing, focus on carrying out seed pesticide dressing measures to effectively control cotton seedling-stage diseases, cotton seedling aphids and underground pests. First, choose seeds coated with a mixture of insecticide and fungicide; second, eliminate sowing untreated white seeds. Seed soaking and seed dressing with pesticides: ① Sulfuric acid delinting of seeds. ② Seed soaking with pesticides can effectively control cotton diseases such as damping-off, anthracnose, red rot, brown spot, black spot, and verticillium wilt and fusarium wilt, as well as cotton seedling aphids and underground pests. To control diseases, use 40% carbendazim suspension concentrate to prepare a solution with an effective ingredient concentration of 0.3%, soak the seeds at normal temperature for 14 hours, remove and air-dry before sowing, or use 300 milliliters of 2.5% Celest (fludioxonil) suspension seed coating agent, add 1-2 kg of water, and mix with 100 kg of cotton seeds, or use warm water seed soaking, that is, before sowing, place the seeds in warm water at 55-60°C and soak for 30 minutes, stirring once every 5 minutes, then remove and carry out pesticide seed dressing. To control cotton seedling aphids, choose 0.5 kg of Xiaoshou water-dispersible granules (70% imidacloprid), add 1.5-2 kg of water, and mix with 100 kg of cotton seeds, or use 0.3 kg of 40% isofenphos-methyl emulsifiable concentrate, add 2 kg of water, and mix with 100 kg of cotton seeds, allow full absorption and air-dry, while also controlling underground pests.

2. Do a good job of pre-sowing weed control. 7 days before sowing, use 75-150 milliliters of 40% trifluralin emulsifiable concentrate per mu, add 30-40 kg of water, spray on the soil surface, and immediately cross-mix with soil, ensuring uniform mixing with the soil, or use 120-150 milliliters of 33% pendimethalin, add 30-40 kg of water, and spray evenly on the soil surface before sowing. This can effectively control annual grass weeds and some broadleaf weeds, saving both labor and effort.

3. Do a good job of disease and pest control at the seedling stage

1. Disease control. At the initial stage of damping-off, anthracnose, seedling blight and red rot, use 50% carbendazim wettable powder at 500-800 times dilution or 75% thiophanate-methyl wettable powder at 800-1000 times dilution for spray control, spraying once every 7 days, generally spraying 2-3 times consecutively depending on the disease condition.

2. Pest control. ① Aphid control. When the leaf-curling rate reaches 3% before the cotton seedlings have 4 true leaves, choose Xiaoshou water-dispersible granules (70% imidacloprid) at 5000-7000 times dilution, or 10% imidacloprid wettable powder at 2000 times dilution, or Sanlianji (5% acetamiprid) microemulsion, or Dikeling (5% acetamiprid) wettable powder at 4000 times dilution for spray control. At the same time, it can be reasonably mixed with organophosphorus pesticides such as omethoate and chlorpyrifos at 1000 times dilution. Control agents should be used in rotation. ② Cotton red spider mite control. Red spider mites mostly gather on the underside of cotton leaves, piercing and sucking sap, causing mechanical damage to cotton plant tissues, and at the same time secreting harmful substances that poison leaf tissues. After cotton leaves are damaged, yellow-white spots of chlorophyll loss first appear, followed by local red spots. The red spots expand and scorch, resembling fire damage. For control, timely "early" control should be carried out. At the stage of spot-and-patch occurrence, choose 5% abamectin at 4500 times dilution, or Jiyate (3% abamectin) at 4000 times dilution, or Haoda (2% abamectin) at 3000 times dilution for spray control. It can be mixed with omethoate emulsifiable concentrate or pyridaben at 1000 times dilution to improve efficacy and reduce costs. ③ Cotton mirid bug control. The main cotton mirid bugs in our province include green mirid bug, alfalfa mirid bug, three-spotted mirid bug and black mirid bug. Adults and nymphs pierce and suck cotton plant sap, causing shedding of buds and bolls, and causing broken heads, broken leaves and clustered branching of cotton plants. Cotton fields with vigorous cotton growth and more buds and flowers have more severe occurrence. With the popularization of insect-resistant cotton in recent years and the reduction in the number of pesticide applications in cotton fields, cotton mirid bug occurrence has become increasingly serious and has become a major pest in cotton fields, occurring 5 generations a year in our province. Before wheat harvest, the cotton seedling stage in our province is the damage period of the first generation of mirid bugs, and at the budding stage it is the damage period of the second generation of mirid bugs. These two periods are the key links for control. For first-generation control, spray when there are about 3 nymphs per 100 cotton seedlings. For second-generation control, spray when there are about 10 insects per 100 plants. Choose Xiaoshou water-dispersible granules (70% imidacloprid) at 5000-7000 times dilution, or 10% imidacloprid wettable powder at 2000 times dilution, or Sanlianji (5% acetamiprid) microemulsion, or Dikeling (5% acetamiprid) wettable powder at 4000 times dilution, reasonably mixed with omethoate or chlorpyrifos at 1000 times dilution. It can also be mixed with 4.5% beta-cypermethrin emulsifiable concentrate at 1000 times dilution for spraying, or choose Lieshi (20% malathion cypermethrin) emulsifiable concentrate at 1000 times dilution for spraying. Multiple agents should be used in rotation to improve the duration of efficacy and control effect.

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