Hawthorn leaf mites are also known as hawthorn red spiders, cherry red spiders, sorrel red spiders, north China, northeast, northwest, central China and other places commonly occurred. Hosts include sorrel, peach, paulownia, ailanthus, locust tree, cherry blossom and so on.
[1] Hazard characteristics
The sorrel grass is damaged, and the leaves initially appear densely greenish and small white dots, after which the leaves die and curl back. Adult, juvenile and nymph mites suck the sap of buds, leaves and fruits of other woody flowers, and many green spots appear in the damaged areas of the leaves, gradually expanding the contiguous patches. In severe cases, the whole leaf is pale and scorched and falls early, often causing the second germination and flowering, weakening the tree potential, not only reducing the ornamental effect of the year, but also reducing the quality of the fruit, or even failing to mature, but also affecting the formation of flower buds and the yield of the following year.
Red spiders harm peach
Red spiders harm sorrel grass
[2] Morphological characteristics
The larvae are rounded and yellowish-white to pale green. Dark green spots appear on both sides of the dorsal side of the body. There are 3 pairs. The nymphs are pale green to light orange-yellow , with bristles on the dorsal area and dark green spots on the sides. There are a full 4 pairs. Start spitting. Later females are ovate, emerald green, with a slightly sharpened end.
Red Spider
【3】Biological characteristics
The algebra occurs in 1 year, varying from place to place, Gansu 5 generations, Liaoning 3 to 6 generations, Shanxi 6 to 7 generations, Hebei 8 generations, Henan 12 to 13 generations, all of which overwinter in clusters of fertilized female adult mites in various crevices of the tree body and in soil cracks near the dry base, in deciduous leaves and dry grasses. The average daily temperature in the following spring reaches 9 to 10 ° C, which is when the apple buds are expanded and spit green, and the pear blossoms are in full bloom, which initially endangers the buds, and after the leaf spreads, it spits silk knots on the back of the leaves. The entire stinging period is about 40 days. Eggs are started within 7 to 8 days of feeding. The egg stage is 8 to 10 days. Since the second generation, the overlap is obvious. Generally, the temperature is low before June, and it takes about 20 days to complete the first generation, and the amount of insects increases slowly. From June to July, when the temperature and drought are high, the breeding can be completed quickly in 9 to 15 days, and the number soars, at this time the flowers are heavily affected, and the adult, young, and mites suck the sap of the flowers and leaves, so that the affected leaves lose green, and dense gray-yellow dots appear, resulting in leaf scorching and early leaf fall; the affected young shoots and flower buds are yellow and scorched, and the leaves cannot bloom. In the rainy season, due to the increase in rainfall and high humidity, coupled with the increase in the number of natural enemies, the insect population density can rise again after early September, and the last fertilized female adult mites will continue to overwinter latently until October. Adult, juvenile, and if mites like to be harmed by the clustering of leaf backs, they spit silk knots into a net, lay eggs on a silk net, and can spread the knots with the wind.
[4] Prevention and control
1. In early spring, the flowers and trees sprout to the branches and spray 5 ° Be stone sulfur compound or 45% crystal stone sulfur compound 20 times liquid, and the oil content is 3% to 5% diesel emulsion.
2. Use Qilin "Mingdikang" to mix 75 to 150 kg of water per set for uniform spraying.
Red spiders harm cuckoos