When shed vegetable production, due to space constraints, air circulation is small, medication is inadvertent, pesticide residues are prone to occur, and human health is affected after consumption. Therefore, the application of pesticides on greenhouse vegetables must be done "three customs."
First, the variety of pesticides. After pests and diseases occur in greenhouse vegetables, the choice of pesticides is more strict than that of open vegetables. It should be selected according to HACCP (Hazard Analysis and Critical Control Point) and GMP (Good Practices) requirements in the National Technical Data for the Production of Pollution-free Vegetables. Drama, high-poisoned pesticides and high-residue pesticides should not be applied on greenhouse vegetables (such as 3911, 1605, etc.), and only pesticides with high efficiency, low toxicity, easy decomposition and short residual period, such as taibao and chlorfenapyr, can be used. , butyl ether urea, Bacillus thuringiensis (Bt), vegetable hi, agricultural Mengte, rice, ether pyrethroid, imidacloprid, alizarin, ketone and other pesticides. It is best to use physical techniques for prevention and control, such as trapping plates (dishers), black lights, and so on.
Second, the use of drugs in a timely and appropriate amount. The use time and amount of pesticides are not suitable, which is easy to cause waste and pollute agricultural products and production environment. When applying pesticides in the shed, it should be flexibly selected according to the requirements. For example, cabbage caterpillars and Plutella xylostella are treated with Bt emulsifiable concentrate 500-1000 times in the low-grade period. When the age of the worms is large, use glutinin (vegetable net) 500-1000 times. Prevention and treatment, the effect is better. The traditional habit of large-dose medications by vegetable farmers often causes waste and pollution. At the same time, it should be noted that bio-pesticide should not be mixed with chemical pesticides and fungicides, and the same type of medicine can be used up to 4-6 times in one season.
The temperature of the greenhouse is different, and the use of pesticides should also be reasonably selected. For example, when Bt emulsifiable concentrate is applied at 30 ° C or above, the drug effect is the best; while the vegetable is in the high temperature of the greenhouse, it is easy to cause damage to melons and lettuce seedlings.
Third, the time to stop the drug is off. The use of pesticides on greenhouse vegetables must be stopped 7-10 days before harvest. In particular, organophosphorus pesticides and heavy metal fungicides should be strictly controlled, otherwise it will cause vegetable pollution.
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