Zhao Lin, Dalu Town, Zhenjiang New District, said on April 27th that he had planted 20 acres of watermelon in a total of 60 greenhouses, of which 35 greenhouses had used 80% of dichlorvos in 20 ml per acre plus 2.4% of Avignon a week ago. Chlorine EC 20 ml water 16 kg spray, after application of watermelon seedlings on the first to wrinkle, and has not yet commenced, the leaves wrinkled scoop-like, darker leaves, the rest did not fight watermelon seedlings did not appear this situation. On the afternoon of April 26th, he sprayed these watermelon seedlings to understand the harmful effects of the leaves and to prevent the yellow leaf dead seedlings. He saw that the dichlorvos product brochure stated that the melon crops were sensitive to dichlorvos. He asked whether the watermelon seedlings were harmed by dichlorvos. Now there are a few ticks in the field. Can they be prevented by the enemy killing 25 g/l of deltamethrin?
It is understood that dichlorvos is a fast-acting, broad-spectrum organophosphorus insecticide that acts on fumigation, stomach poisoning, and contact poisoning. The drug can volatilize into gas at room temperature, and it can cause poisoning by entering into the body through the pores of insect pests. It can also enter the body through the oral cavity of pests and be poisoned by the absorption of the digestive tract, or it can cause poisoning by penetrating into the body through contact with the body. The melon crops are sensitive to dichlorvos and cannot be applied during the seedling stage. In the adult plant stage, the concentration and dosage should be strictly controlled, otherwise it is easy to produce phytotoxicity. Symptoms of injury to the leaf first become purple, then become bright red or light yellow, veins keep green first, then turn yellow. Zhao Lin reflected that the appearance of tender head shrinkage, scooping of leaves, and darkening of leaf color of watermelon seedlings after application was not as much a result of the damage caused by dichlorvos.
It is also known that the application of pyrethroids such as fenvalerate and deltamethrin to watermelon may cause injury to watermelons. Fenvalerate injury symptoms of watermelon seedlings young leaves yellow edges, the formation of Phnom Penh leaves or yellow patches, slow growth. The greater the concentration of pesticide application, the heavier the hazard. The deltamethrin injury symptoms were dark green leaves, thick leaves, leaf margins, growth point growth stagnation, no new leaves and vines. It has been reported that the pyrethroid pesticide products that are likely to cause phytotoxicity to melon crops are mainly emulsifiable concentrate preparations. The xylene and ethanol contained therein are liable to produce phytotoxicity to melon seedlings, and they are more likely to cause injury during use on watermelons. . Switch to other formulations of pyrethroid pesticides, such as microemulsions, soluble powders, will not have adverse effects. In addition, the application of pesticides in the high-temperature period is more likely to occur in phytotoxicity than in the low-temperature period. The above Zhao Lin reflects that the symptoms of watermelon seedlings after application are similar to those of pyrethroid pesticides and are likely to be caused by pyrethroid pesticides. After the watermelon seedlings are harmed by phytotoxicity, the sprayed solution and the yellow leaf dead seedlings' leaf fertilizer can relieve the symptoms of the phytotoxicity to some extent.
To prevent and treat aphids on watermelon, do not use the enemy to kill 25 g/l of deltamethrin EC. You can use acetamiprid, imidacloprid, thiamethoxam and other agents to avoid phytotoxicity. Pay attention to avoid medication during high temperature.
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