1. Thrips
Thrips belong to the animal kingdom, arthropoda, insect class, Thysanoptera; their mouthparts are special "rasping and sucking mouthparts". They mainly feed on rasping and sucking plant sap, causing damage to plants.
Thrips are common in the production of eggplant, pepper and melon vegetables. Once they occur, they are difficult to eliminate. They are a kind of pest that vegetable farmers are more worried about.
The peak period of thrips is from November to December in autumn or winter, and the second peak period is from March to May. Female adults mainly reproduce parthenogenetically, and occasionally reproduce sexually. It is extremely rare to see male insects.
Thrips like warm and dry weather. The suitable temperature is 23℃-28℃ and the suitable air humidity is 40%-70%. They cannot survive if the humidity is too high. When the humidity reaches 100% and the temperature reaches 31 ℃, all nymphs died.
After thrips infest the upper tender leaves, the leaves become thinner and curled, and there are grayish-white chlorotic spots on the mesophyll; when the terminal buds are damaged, the growth point atrophy and other symptoms are prone to occur.
When young fruits such as peppers are damaged, "scar fruit" is prone to appear in the later stage, and corky grayish-white spots of different shapes appear on the surface of the fruit skin. The reason is that after the young fruits are bitten by thrips, the fruit skin cells lose water and shrink, leaving small scars on the fruit surface. As the fruit expands in the later stage, the scars are elongated or expanded.
After thrips infest, the reverse side often presents a "bright skin" situation, which is scattered when light and connected when heavy, and can also be found on the front side.
2. Mites
Mites, such as tea yellow mites, mainly harm the delicate tissues of vegetables, pierce and suck the stems, leaves, and fruits of vegetables with their mouth needles, and mainly harm the growth points and young fruits of plants. , often causing leaves and fruits to be deformed or cracked, turning gray or brown, plant growth to be stunted, and growth to be weak.
It is precisely because mites mostly harm the growth points of plants that their symptoms are similar to those of hormone poisoning or viral diseases. Vegetable farmers must learn to identify them and never misdiagnose or mistreat them, so as not to miss the opportunity for prevention and control and cause a large outbreak of mites.
Mites have disease centers in the field, and they mostly occur in sections. After the leaves are damaged, the back turns brown with oily gloss, twisted and deformed, and curls downward, which is different from viral diseases and hormone poisoning; after the fruit is damaged, the peel is "rusty", yellow-brown, corky, and cracked.
The mites are mainly two-spotted spider mites and tea yellow mites. Vegetable farmers should regularly observe the growth points and leaves of vegetables near the vents. After thrips infestation, they often appear "bright" on the back. "Skin" situation, scattered when light, connected in a piece when heavy, and can also be found on the front.
Prevention and control measures
In recent years, many vegetable farmers have reported that the effect of spraying pesticides to kill pests is very poor. In addition to the resistance of pests to pesticides, there are two other reasons: the wrong time and method of use, and the unreasonable choice of pesticides.
First, the time and method of spraying pesticides for different pests are different. There are some particularities when using pesticides for thrips and mites. In addition to the above two points, the following points should also be achieved:
Thrips are dormant during the day and come out at night, so the spraying time should be chosen in the afternoon. After spraying, thrips will come out to feed, which will have a much better effect. In addition, thrips lay eggs in the leaf pulp tissue. If contact pesticides are used, it is difficult to kill their eggs, which is a temporary solution but not a permanent solution.
(1) Timely deal with plants seriously damaged by thrips, destroy them in a centralized and unified manner, and eliminate overwintering insects.
(2) For pesticide control, choose pesticides with good contact and systemic properties for control. For example: Imidacloprid and acetamiprid are commonly used, and some use thiamethoxam and spinosad. I will not introduce too much about this point. The key points are as follows:
① One characteristic of thrips is that when the temperature of the greenhouse reaches 16-19℃ or above, they begin to move from the soil to the plants and prepare to feed and cause harm. From this point of view, we must accurately prevent and control according to the temperature of the greenhouse.
② In addition to causing harm to the plants, up to one-third of thrips are still in the soil. Therefore, when preventing and controlling, in addition to spraying the upper part, you must pay attention to spraying the ground at the same time!
Mites are mostly distributed on the back of the leaves. If you follow the normal spraying method, the liquid is mostly concentrated on the front of the leaves, and it is difficult to contact the mites on the back of the leaves, and the insecticide effect is poor. Therefore, when spraying the mite-killing agent, the sprayer nozzle should be sprayed at an angle of 45° upwards.
In fact, the problem of spraying methods can be solved by the mist machine on the market. It not only saves labor and time, but also sprays the medicine comprehensively. However, when using it, you must understand whether the agent is resistant to high temperatures.
The mites are mainly two-spotted spider mites and tea yellow mites. According to the characteristics of avermectin's special effect on two-spotted spider mites and cypermethrin's good control effect on tea yellow mites, cypermethrin 1500 times mixed with avermectin 2000 times can be sprayed for treatment.
Thrips reproduce quickly and easily become a disaster. They often hide on the back of leaves or in flowers during the day. Therefore, spraying and fumigation can be used for prevention and control. Shed households can spray 2000 times of Caixi on the leaves before closing the shed in the evening. Or fumigate aphid fume or imidacloprid fume.
In addition to chemical control, physical control measures and methods to improve environmental conditions can also be taken, such as hanging insect-proof nets of 300 mesh or above at the vents.
Blue board trapping! Thrips have the habit of tending to blue. Using blue boards to trap and kill adults can reduce the population density of harmful species. Regularly filling the canal with water and increasing the air humidity near the vents is also conducive to avoiding thrips and mites.
