Autumn is the most harmful season of tea mites on peppers, eggplants, cucumbers, loofahs and other vegetables, due to the small size of the insects, it is difficult to find with the naked eye, often mistaken for viral diseases, missing the best control period, coupled with the tea mites breeding speed is particularly fast, often causing serious yield reduction, how to quickly and efficiently control the harm of tea mites?
1. Harmful symptoms
Tea yellow mite is also called side multi-food tarsal mite, tea young leaf mite, tea half tarsal line mite, commonly known as white spider. Adult mites and young mites are mainly harmful, and adult mites and young mites concentrate on the young leaves, young shoots, buds and young fruits of the host to suck sap. The leaves become smaller and narrower after being killed, the back of the leaf is yellowish brown or grayish brown, with an oily luster, and the leaf margin is curled to the back, thickening and stiffening. After the young shoots are killed, they twist into rotunda, yellow-brown, stop growing, and die later. The buds are deformed after being killed, and in severe cases, they cannot flower and bear fruit. After the fruit is killed, the epidermis of the victim site is rough, and the growth of the young fruit is slowed down, forming a stiff fruit, the flesh is hard, and it loses its edible value. Severely damaged pepper plants, short and overgrown, deciduous leaves and flowers form bald tips.
2. Morphological characteristics
The tea mite is difficult to see with the naked eye, and is visible under a magnifying glass, the female mite has a broad ovate body, a flattened abdomen, pale yellow to orange yellow, translucent, shiny. The body segments are not obvious, and there is a longitudinal white band on the back of the body. Foot 4 pairs, shorter. The surface of the egg has 5-6 rows of white nodular protrusions arranged longitudinally.
The juvenile mites are nearly oval and pale green. There are 3 pairs of feet, 1 white longitudinal band on the back of the body, and 1 pair of bristles at the end of the abdomen. If the mite is generally stationary, inactive, does not feed, and is covered with the skin of the young mite.
3. Occurrence characteristics of tea yellow mites
(1) Tea yellow mite life cycle is short, the reproduction rate is fast, can occur 25 to 30 generations a year, overlapping generations. Adult mites overwinter in soil crevices, vegetables and weeds at the rhizosphere. In most parts of the north, tea mites cannot overwinter in the open, but can overwinter or breed in protected areas in winter. In the South, it can occur and be harmful all year round.
(2) Tea mite occurrence has obvious seasonal changes, warm and humid ecological environment is conducive to the growth and development of tea mites, the most appropriate temperature for the propagation of tea mites is 22 ~ 28 °C, relative humidity 80% ~ 90%, when the temperature is 29 ~ 32 ° C, it takes only 4 to 6 days to complete a generation, when the temperature reaches 34 ° C ~ 35 ° C, after 2 to 3 hours, if the mite mortality rate can reach 80%, the adult mite mortality rate is as high as 60%.
(3) Tea yellow mites have tenderness, and adult mites and young mites are mostly concentrated in the young parts of the plant, especially like to inhabit and feed on the back of young leaves. Male mites are highly mobile and have the habit of carrying female mites to the young parts of the plant. Eggs are scattered on the back of young leaves, in depressions in fruits or on young shoots.
4. Prevention and control methods
In the initial stage, 18% avyl acetiazole suspension 15 to 10 ml, or 45% dihydrazine acetazole suspension 10 to 15 ml, or 30% ethazole nitrile suspension 10 to 15 ml, mixed with 30 kg of water evenly sprayed, focusing on the upper part of the plant on the back of young leaves, young stems, flower utensils and young fruits. The above agents are used in rotation. Spray once every 10 days for 2 to 3 consecutive sprays. It can completely kill most pests and mites, and the effective period can reach about 50 days.
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