What should we do after longan gets gall mites?

Longan, (Latin name: Dimocarpus longan Lour.) also known as longan, Yizhi, evergreen trees, tall trees. From July to August, the fruit was picked when the fruit was yellowish brown. It is a plant of the disease-free family, the fruit is used for raw food or processed into dried products, and the meat, nucleus, skin and root can be used as medicine. Originated in the south and southwest of China, longan is cultivated in many countries and regions in the world, such as China, Thailand, Indonesia, Queensland in Australia, Hawaii and Florida in the United States.

Longan gall mite (Eriophyesdimocarpi) belongs to the family Acaridae of arachnida, which is a new harmful mite in longan production and a new species of mites discovered in recent years. It harms the leaves of longan and causes a large number of leaves to fall off in spring, especially in the weak plants, resulting in a decrease in yield or even no fruit. Because the insect is small and difficult to see with the naked eye, it is often mistaken for disease symptoms, or for chlorophyll discoloration caused by lack of light, so it can not take targeted measures to prevent and cure it in time. Therefore, it is necessary to introduce it.

1. Morphological characteristics 1? Adult mites: tiny, indistinguishable to the naked eye, carrot-shaped, yellowish to grayish white. The head is small, stable under the back of the chest, and there are tortoise shell-shaped spots on the back of the chest, with 3 horizontal lines of 7 to 8 pieces each. There are two pairs of short feet on the ventral side, about 40 rings on the back of the back of the abdomen and about 60 rings on the ventral side. There is a pair of bristles on both sides of the third ventral segment. two? Nymph: the body is similar to that of an adult mite, with a body length of 0.077 mm, milky white, translucent, round and blunt head and obvious abdominal ring pattern. three? Young mites: the body looks like an adult mite, but the head and chest is larger than the abdomen, slightly round, the body is sharpened, 0.065 mm long, white, translucent. There are 2 pairs of feet with obvious ring lines on the abdomen. When approaching desquamation, the foot shrinks inward, the body surface is in the shape of a film, and the whole body is arched. four? Egg: helmet-shaped, 0.04mm in diameter, about 0.013 mm thick, white, translucent, shiny.

2. Harmful symptoms: adult mites, nymph mites and young mites of longan gall mites can all feed on the leaves that harm longan, but only harm the mature foliar tissue and pierce the foliar cells with mouthparts to absorb juice, but the harm has not been found on the back of the leaves. After the cells were destroyed, the damaged area became moist at first, then turned grayish brown, and finally became purplish brown. The photosynthesis of the injured leaves decreased or even lost completely, and the life span was shortened. Because the cuticular layer of the leaf is not destroyed and the luster of the leaf does not fade, especially in winter, it is often mistaken for seasonal physiological changes or because the insect body can not be seen and is caused by disease.

Third, the occurrence regularity of longan gall mites is harmful all the year round, multiple generations occur in a year, and generations overlap. Cloudy days or areas with poor light, or dry and overcast weather in winter, are conducive to its harm. The insect has the habit of swarm damage, which first endangers in the shade, then spreads out, and lives semi-freely.

Fourth, prevention and control measures should be willing to cut down trees in densely planted orchards, so that the planting density of orchards is reasonable, ventilated and transparent. The shaded inner bore branches, drooping branches or overdense branches should be cut off in time. Once a damaged branch is found, it should be cut off and burned immediately. For chemical control, the injured plants were sprayed with 20% diclofenac EC to water, or 15% diclofenac EC to water 1500 times and miba EC to water 2000 times.