China Pesticide Network reminds: summer is the high season of cockroach pests, and fruit farmers should strengthen prevention.
First, the symptoms of harm
1. Hawthorn leaves. Also known as Hawthorn red spider, mainly harms the leaves, shoots and young fruit of apple trees. When the leaves are damaged, the red spiders colonize the back of the leaves, sprinkle the net, adhere to the fine soil and egg on the screen, and many pale spots appear on the front of the leaves. When the damage is serious, the rust-colored symptoms appear on the back of the leaf, and then the water is dehydrated and hardened. The whole leaf turns yellow-brown and burnt, and it looks like a fire. In the orchard with serious damage, most of the leaves can be shed during the period from June to July, and secondary flowering and germination occur. The buds with serious damage cannot continue to grow and die.
2. Fruit Taiwanese. Fruit Taiwanese owl, also known as apple long-leg red spider, red spider, mainly eats on the front of the host leaf, can form large chlorotic spots, and there is no rust on the back of the leaf. This kind of red spider does not sprinkle the net, and the affected petiole, branches and the like are attached with a large amount of white suede, which can cause the leaves to dry and fall off.
3. Apple full claws. Also known as apple red spider, the tender buds often can not normally spread the leaves and flowers, and even the whole buds die, the affected leaves are covered with yellow-white spots on the front, and finally the whole leaves are yellow, generally do not mention early leaves, and do not draw silk netting.
Second, the law of occurrence
1. Hawthorn leaves. 6 to 10 generations occur in 1 year, the fertilized females overwinter in the cracks of the bark, under the rough skin and in the ground soil. Generally, the damage is lighter before June, and after the middle and late June, the breeding under the high temperature and dry climate is very Fast, entering the stage of serious harm in July, can cause a lot of fallen leaves. From late July to early August, with the arrival of the rainy season and the increase of natural enemies, the density of insect populations gradually decreased. By mid-August, most females had entered the wintering place, and some could continue to winter in September-October.
2. Fruit Taiwanese. Three to seven generations occur in one year, and the eggs are overwintered in the shades of the main branches and side branches, and in the fruit trees. When the apples sprout in April, they begin to hatch. From mid-June to early July, the hazards are the most serious. Generally, eggs appear in early August.
3. Apple full claws. 6 to 9 generations occur in 1 year, and the eggs are overwintered on the fruit table, fruit marks and biennial twigs. The high temperature drying is beneficial to the breeding hazard of the apple tree.
Third, prevention measures
In order to prevent and control cockroach pests, in addition to dormancy prevention and control, and according to the law of occurrence of red spiders, grasp the three key periods before and after flowering and before wheat harvest, spray at appropriate time, and pay attention to late control. In order to reduce the winter insect population, the damage of the red spider can be effectively controlled. At present, it is the high-incidence period of the early harvest period, which should use 25% of the broom net 600-800 times liquid and 20% of the anti-sweeping emulsifiable concentrate 3000 times liquid for prevention and treatment. In addition, there are many natural enemies of three kinds of red spiders. Commonly, there are natural enemy insects, predatory mites and pathogenic microorganisms. The production should pay attention to protection and utilization.
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