Control of thrips growing cotton

Cotton thrips are also called tobacco thrips and spring onion thrips. In addition to harming cotton, it also harms tobacco, onions, garlic, melons, potatoes, tomatoes, cabbages and other crops.

Symptoms of damage: adults and nymphs are mostly concentrated in the tender head and leaf back of cotton plants to absorb juice. after cotton seedlings are killed, cotyledons are thick, small yellow-green or silver-white spots appear on the back, the growth point is scorched and can not grow new branches, and cotton farmers are called "male cotton" or "headless cotton"; although some can grow new branches, the growth point is divided into several forks, and cotton farmers are called "multi-headed cotton" and "loose head flowers". The former caused the lack of seedlings, while the latter delayed the growth period of cotton and reduced the yield due to less bolls.

Occurrence regularity: adults or nymphs overwinter on crops such as green manure, rape, onions and garlic. After the spring is warm, it first propagates on the host crop, and then moves to the cotton seedlings to do harm. Cotton thrips occur heavily in cotton seedlings that are close to the overwintering host or where there are many weeds nearby. Generally loose soil is favorable for its occurrence, while clayey soil is disadvantageous to its occurrence. The early sowing of cotton field is more serious than that of wheat interplanting cotton. Cotton thrips are suitable to occur in drier years. In particular, when the temperature is below 25 ℃ and the relative humidity is about 70% from May to June, the damage is often serious; when the temperature exceeds 25%, Rain Water is more, and the humidity is high, it is disadvantageous to thrips. Therefore, the damage of cotton thrips decreased significantly after the middle and late June in general years.

Control measures 1. In the mixed planting area of cotton and vegetables, the control of onion and garlic vegetables should be strengthened to reduce the base number. Can be sprayed with 2000-2500 times of dimethoate emulsion. 2. Combine inter-seedling and fixed seedling, pull out "male cotton"; when "multi-headed cotton" is found after seedling setting, the young and sturdy tillering branches should be removed, leaving thin brownish branches, so that the final boll number is close to the normal cotton plant. 3. The damage period of cotton thrips is generally earlier than that of cotton aphids. After the cotton seedlings are unearthed, the investigation should be strengthened and the control should be carried out as soon as possible. Use 3% acetamiprid 50 ml per mu, or 2500 times 40% dimethoate emulsion, or 5% phosphoamine emulsion 50 ml. 60 kilograms of spray liquid per mu. 4. Soil pesticide control. Tobacco, lime water. Raw materials: tobacco, quicklime, water. Mix method: first use a small amount of hot water to calcinate 1 kg of raw lime, pour into 40 kg of clear water, filter the residue. Then tear up 1 kilogram of tobacco and cover it with 10 kilograms of boiling water. when the hot water is not hot, rub the soaked tobacco with your hands and change the water constantly until there is no leaf juice flowing out (1 kilogram of tobacco leaves can be kneaded out of 30-40 kilograms of tobacco water). Pour the tobacco water into the lime water. Then spray it with tobacco lime water.