In recent years, corn red spiders have been widespread and are more harmful. The degree of damage, spring corn is heavier than summer corn. Corn red spiders also harm cotton and bean crops. In corn and cotton interplanting areas, corn is more harmful than cotton. At the beginning of July, the corn red spider was firstly damaged on the leaf back of the corn near the ground blade. There was a thin mesh covering on the back of the leaf, and then gradually transferred to the middle and upper leaves, and the middle and late July was the end of the hazard. The 1000-grain weight of the damaged corn is generally reduced by 30-50 g. In severe cases, all the leaves turn gray-green, and even dry and die, and the 1000-grain weight is reduced by about 100 g. It is necessary to timely carry out pesticide control.
The corn red spider has strong drug resistance, and various insects mix and occur, and it is inhabited by the leaf back mesh to feed. The effect of applying the general insecticide is not obvious. The use of acaricide and a systemic insecticide with good egg-killing effect to control corn red spider has an ideal effect. For example, 20% dicofol 1000 times solution is effective for each insect state, the efficacy period is 5-7 days; the systemic insecticide 40% monocrotophos, 40% omethoate, 50% methamidophos 1000-1500 Double liquid, the efficacy period is 7-10 days, and it is stopped 20 days before harvest to prevent pesticide residues. It is also good to control with 1000% 2000% 2000 times of the 20% double nail emulsion. Spray with 80% dichlorvos 1500 times liquid at noon on sunny days, you can kill ruthenium and cockroaches within 1 hour, but the egg-killing effect is poor, and it needs to be controlled once every 3-4 days. It is better to spray the liquid on the back of the leaf when spraying.
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