Sweet potato moth, also known as sweet potato leaf leaf worm, is a kind of pest which uses larvae to make silk leaves and takes leaf meat in the leaf to harm it. It mainly damages sweet potato, leeks and other convolvulaceae plants. In recent years, there has been a trend of increasing harm in our country. According to the survey, the damaged leaf rate is generally 60% -70% on sweet potato, and serious land mass is more than 90%, causing losses to the production of sweet potato; after damage, the leaves and young shoots are eaten. Affects the growth of leeks and seriously affects their quality, reducing the value of food and the value of goods. First, the law of occurrence and hazard characteristics Sweet potato moth in our land occurred in 3-4 generations, overlapping generations. The worm passed the winter in stubble and deciduous fields of the field, began to eclosion in winter in early winter, and saw larvae in the field in late June. After the middle of August, the densities in the field increased and the damage increased. Old mature larvae pupate winter. The adults of the sweetpotato moth have strong phototaxis and lively action. They lurk in hidden places in the fields during the day and copulate and spawn at night. The eggs are usually spawned between the veins on the back of the leaves, and a few eggs are produced on sprouts and tender stems. The larvae were divided into 4 instars, of which the 1st instar larvae only ate leafy leaves on the leaf surface, but did not perform leaf rolling but drooping; the 2nd instar larvae began to spit for a small part of the leaflets and feed on the leaves within the leaf wounds. Sweet potatoes and leeks; after 3rd year of age, the larvae's food intake increased greatly, the degree of leaf rolling also increased, and there was a habit of transferring damage, and a larva could damage 10 leaves from small to large. In addition to the major damage to the larvae, the larvae also eat tender stems and young shoots. The victim's leaves and leaves were eaten, leaving only a white skin, like a thin film. In severe cases, the leaves of most leaves are eaten and eaten, showing a "fire" phenomenon, affecting the normal growth of sweet potatoes and leeks. After the killing of the leeks, the quality deteriorated, and the food value and commodity value decreased. The damage of sweet potato plants in the early growth period affected the supply of nutrients and delayed the growth of sweet potatoes. During the period from September to October, sweet potato roots swelled. At the same time, the density of insect populations in the field increased, a large number of leaves were damaged, photosynthesis decreased, and the expansion of tubers was hindered. Loss of production can reach more than 10%. Second, prevention and control measures According to the occurrence rule and damage characteristics of sweetpotato moth, prevention and control can be started from two aspects of agricultural control and chemical prevention, in the leek should be based on agricultural control, supplemented by chemical control. (1) Agricultural control 1. Clean the pastoral area in the autumn to deal with stubble leaves, remove weeds, eliminate overwintering mites, and reduce field pests. 2. When larvae are wounded in the pastoral field, the larvae in the new leaves must be pinched in time or new leaf should be removed. (2) Chemical control Drug control should be applied in the early stage of larval emergence. Spray time should be 4-5 pm, and the control effect is better. The preferred agent is sprayed with 48% of Le Siben EC 1000-1500 times, and the efficacy is up to 90%. In addition, sweet potato fields can be used 50% methamidophos EC 1000 to 1500 times, 40% monocrotophos EC 1500 to 2000 times and 40% omethoate EC 1000 to 1500 times spray; 20% on leek Diflubenzuron suspension agent 1500-2000 times liquid, BT emulsion (100 billion spores / ml) 400-600 times liquid, 40% Dimethoate EC 000-1500 times spray control, the effect is better. Special emphasis was placed on the application of 48% Le Siben EC and 40% Dimethoate EC on the amaranth, which should be harvested 7 days after application.
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