Chestnut claws
? Oligonychus ununguis Alias ​​chestnut red spider, chestnut leaves.
Damage symptoms
The leaves were rotted green, yellowish-white dots, and severely damaged leaves were brown and brown. The front of the leaf clusters along the sides of the main vein, and there is a small amount of spider silk around it. When the big leaf occurs, there is also a small amount of cockroaches and eggs on the back of the leaf.
??Morphological characteristics
Females become oval-shaped, about 0.5 mm in size, and slightly red in brown. Male into a diamond body, compared to some female eggs? Spherical, dark red at the top of the depression, the summer egg yellow, a white silk hair at the top of the egg.
Cubs, young red eggs hatched from winter eggs, milky white eggs hatched from summer eggs, and brown or green-brown after feeding, with 3 pairs of feet.
If the carcass are green-brown, it seems to be a pod, with 4 pairs.
??
?? Occurrence characteristics?? 4 to 9 generations a year, the egg in the 1-4 years of birth on the back of the branches of leaves, rough skin, cracks and branches over the winter. Take the most in two or three years. The wintering eggs hatch from late April to early May of the following year. The peak period ends in mid-May and early June. The young cub climbs to the base of the new shoot and damages it as the new shoot grows. In the second half of May, the first generation of Scorpio appeared. Until mid-October, females lay eggs on average 40 to 70 capsules a day, and eggs last for 8 to 15 days. Each generation gradually overlaps, and it is the heaviest damage from June to July in the third to fifth generation flood season. The fade period of chestnut leaves is the critical period for prevention and treatment. After early September, Chengyu gradually spawned winter.
The summer eggs are mainly on the main veins of the foliage, and the winter eggs are mainly on the branches. Chengyu is on the leaf surface, and the insect population is significantly reduced when it is hit by wind and rain. The number of wormholes in dense planting gardens is large, and the occurrence of sunny slopes is early and heavy. The year of high temperature and drought occurs early and heavy. Natural enemies include black ladybugs, red star ladybugs, grasshoppers, and whiteflies.
?? Prevention methods
?? 1, pruning in winter, scraping bark, shave tree disk, eliminate overwintering eggs and adults. From late March to early April, 3 degrees lime sulfur was sprayed on newly planted saplings and grafted trees.
?? 2 in early May drug dried. Cut a ring with a width of 5 to 10 centimeters wide on the tree trunk and scrape only the rough skin. Apply 50% Dimethoate EC, or 40% Omethoate ECG 5 times, or 20% monocrotophos 20 times to dry, lightly dry, then apply again, then use mulch (or plastic film, waste kraft paper) Wrap it well and it works well.
From late May to late June, commonly used acaricides can be sprayed.
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