How to control cotton mirid bugs? These methods must be mastered

The occurrence of mirid bugs is very sensitive to the ecological environment. Mirid bugs prefer temperatures of 25°C~30°C and a relative humidity of 80%~90%. The recent humid weather with little sunshine is very favorable for the occurrence of mirid bugs. Intercropping in cotton fields is also conducive to the parasitism and transfer damage of mirid bugs. Now, soybeans, broad beans and other vegetables are intercropped in cotton fields everywhere, which is conducive to their reproduction. Therefore, some cotton farmers in cotton areas of counties and cities such as Hanchuan and Yunmeng in Hubei Province have recently reported that the occurrence and damage of mirid bugs have already emerged, which must arouse our high attention.

There are many species of mirid bugs. The main ones damaging cotton include the green mirid bug, alfalfa plant bug, black mirid bug, and three-spotted mirid bug. They can cause damage at every stage of cotton growth and development. The damaging effects of mirid bugs are, first, using their piercing-sucking mouthparts to pierce into the young and tender organs of the cotton plant and suck the sap of the tender tissue, and second, injecting saliva into the young and tender organs of the cotton plant, causing cell necrosis or deformed growth. After the growing point is damaged at the cotton cotyledon stage, the injured tender tip dries up and no new buds grow again, commonly known as male cotton; when 3~5 true leaves are damaged at the seedling stage, the terminal bud will also be pierced and killed, but new buds can still sprout from the leaf axils, regenerating secondary fruiting branches to form multi-headed cotton, called broken-head madness in some places; when young leaves are damaged, small black spots first appear on the leaf surface, and the damaged holes then become irregular holes of various sizes, commonly known as broken-leaf madness; when the tips of fruiting branches are damaged, vegetative branches sprout from the leaf axils, forming broom-like seedlings; when young buds are damaged, one case is that they dry up after 2~3 days, another is that the bracts open and then the young buds fall off, and the third is that large buds show black spots when damaged and the flowers cannot open normally; when young bolls are damaged, the epidermis shows dark brown water-soaked spots, and in severe cases the cotton bolls become rigid and fall off, or are covered with black spots, reducing quality.

In view of the lessons from mirid bug damage over the years, all localities have forecast that mirid bugs have a tendency to break out this year. Therefore, preventive measures should be taken as early as possible. In terms of agricultural control, first, weeds around the cotton field should be cleared; second, the ditches and beds in the cotton field should be dredged to reduce humidity; third, regulatory measures should be applied to shape a cotton plant type with good ventilation and light transmission; fourth, nitrogen fertilizer should be reduced and phosphorus and potassium fertilizer increased. In terms of chemical control, first, 25% imidacloprid for mirid bug control and mineral oil at 1000~1500 times liquid can be used; second, 2% emamectin benzoate wettable liquid at 5000 times liquid can be used; third, 3% acetamiprid emulsifiable concentrate at 1500~2000 times liquid can be used; fourth, 10% imidacloprid wettable powder at 1500 times liquid can be used; fifth, 35% Liansheng suspension concentrate at 5000~6000 times liquid can be used; sixth, 90% Kuailing wettable powder at 6000~8000 times liquid can be used; seventh, 40% chlorpyrifos or 48% Lorsban emulsifiable concentrate at 1000~1500 times liquid can be used. Various pyrethroid emulsifiable concentrates can also be used.

The above pesticides can be selected and applied by each locality according to local conditions, but they should be used alternately. In terms of application technique, the control time should be earlier, generally starting from late May to early June, and spraying 3~4 times successively in combination with the control of other pests. When spraying, first spray around the cotton field, and then spray the cotton in the middle of the field, to prevent mirid bugs from fleeing. Since mirid bugs are mostly active in the evening, spraying after 5 p.m. is better.