Occurrence and control of tea mites in greenhouse

In the production of fruits and vegetables in the greenhouse, it is often seen that the growing points of some seedlings are curled and shrunk, and the fruits are deformed and cracked, which cause serious losses to the production. Because the temperature and humidity in the shed is very suitable for the growth and reproduction of tea yellow mite, fruits and vegetables are its main targets, the mite is very small, and people can not see it, so it can not be prevented and controlled in time. Therefore, the area of damage has become larger and larger in recent years, which should be paid great attention to by the majority of producers.

Tea yellow mite is a harmful micropest of arachnida, acaridae and tarsus acaridae. It is mainly harmful to cucumbers, eggplant, tomatoes, green peppers, beans and other fruits and vegetables in greenhouse vegetables. Mites cluster in the tender parts of vegetable seedlings to harm by piercing and sucking. The back of the damaged leaf is grayish brown or yellowish brown with oily luster. (this is the main difference from virus disease) the edge of the leaf is drooping and curling. The damaged leaves of the heart leaves become narrow, stiff and erect, wrinkled, twisted and deformed, and when severe, the top dries up and dies. The damaged flowers do not bloom and fall off. The epidermis of the damaged fruit was rough, corklike, yellowish brown and dull. Eggplant, tomato fruit cracked, in the shape of flowering steamed bread, bitter taste, can not be eaten.

Because the mite body is so small that it can not be seen with the naked eye, the oval transparent insect body can only be observed under the anatomical microscope, so it is easy to mistake the above damage for physiological disease or virus disease.

The adult mites of tea mites overwintered on vegetable seedlings, weed roots or soil cracks in the greenhouse in winter, and began to breed from March to April in the following spring. The suitable temperature for development and reproduction is 16-23 degrees. When the relative humidity is 80%-90%, a generation can be completed in 7-10 days. The mature male mites are active, and when the feeding site becomes old, the young female mites can transfer to the tender tip, and the mating reproduction will continue to do harm.

Because the tea yellow mite has a short life cycle, strong fecundity, a large number of harmful crops and concealment, and because it is a pest of the family acaridae, the control effect of general insecticidal drugs is not ideal, so it is difficult to control it, so it is necessary to give priority to comprehensive prevention. comprehensive control can achieve good results.

1. Use sulfur powder to fumigate the insect source. Although the tea yellow mite can also survive in the greenhouse in winter, it has a small population, slow reproduction and low resistance. We should seize this favorable opportunity to cure it in time to prevent it from spreading. The method is to carefully remove the residual branches and leaves, pull out weeds and close the greenhouse after pulling seedlings in the previous stubble of greenhouse vegetables and before raising seedlings in the next stubble. Every 100 square meters of greenhouse, 0.5 kg of sulfur powder is mixed with a double amount of dry sawdust, and 2: 3 piles are lit and smoked for 24 hours in a windless night (preferably on rainy and snowy days). The seedlings can be raised or planted after 7 days. However, it must be noted that when fumigating with sulfur powder, growing vegetables and people and animals are strictly prohibited in the shed to prevent accidents. In addition, vegetables during the growing period are not allowed to use this method to kill insects. This method has a good effect on the control of scab and other pests.

2. Rotation. The rotation of fruits and leeks, lettuce, Chinese cabbage, rape, coriander and other cold-tolerant leafy vegetables can reduce the damage.

3. Drug prevention and treatment. The drug control of tea yellow mites should adhere to the principle of early treatment and treatment. When a small number of injured plants are found, the injured plants can be removed and burned in time, and at the same time, 2000 times of 5% nisolone EC can be sprayed every 6 to 7 days, and can not be mixed. Spray 3 times in a row for 5 times. Combined with insecticidal fumigant fumigation, once every 5-7 days, for 2-3 times, the effect is better.

The production practice has proved that due to the long-term use of triclofenac, dichlorvos EC, dimethoate and other pesticides commonly used in the past, tea mites have obviously developed resistance to it, so the control effect is poor or basically ineffective, and should be avoided so as not to delay the opportunity of prevention and control.