Occurrence and control of corn borer

Corn genus Lepidoptera, Scorpionidae. Distributed in Europe, North America, Northwest Africa, the dominant species in China is Asian corn borer. European corn borer is mainly distributed in Inner Mongolia, Ningxia and Hebei. These provinces are European corn borer and Asian corn borer mixed area, and Changji is mainly European corn borer. The host of corn borer is more than 200 kinds of plants such as corn, sorghum, millet, cotton, hemp, beans, sweet potato, beet, tomato, pepper and wheat.

Hazard characteristics The larvae of the heart leaf of the corn feed on the mesophyll or feed on the unexpanded heart leaves, causing the "flowers". After the heading, the stalks are drilled, the development of the ears is hindered and the yield is reduced, and the pupils are easily folded. At the ear stage, the ears and tender grains are eaten, resulting in grain defects and mildew, and the quality is degraded. Reduce production by 10% to 30%.

Morphological characteristics Adult wings are 25-35 mm, yellow-brown, female moths are thick and strong, and the front wings are bright yellow. The wings are 2/3 with brown stripes and a brown corrugated line, and the outer side has yellow jagged lines. The male moth is thin and has a slightly darker wing than the female moth. The head, chest and fore wing are yellowish brown, and the back of the chest is light yellowish brown. The transverse line of the fore wing is dark brown, corrugated, yellowish brown on the inside, brown at the base, dark brown on the outer horizontal line, serrated, yellowish brown on the outside, and brown with the outer edge parallel to the outer edge, brown between the inner and outer transverse lines, rear wing Light brown. The punctured area of ​​the spores of the abdomen is shorter than the thornless area at the base of the front, usually with 3 thorns, sometimes with 2 large thorns or 4 thorns containing 1 small thorn, and the average number of thorns is less than that of Asian corn mash.

Habits of life European corn borer occurs in Changji every year for the second generation, and the mature larvae overwinter in corn stalks, root stalks and ears. The wintering larvae began to phlegm in early May, and the middle and late May were the peak of emergence, and the mid-June was the peak of spawning. The first generation of adults appeared in mid-July, from the end of July to the beginning of August for the adult and egg-bearing period, the mid-August was the larval period, and the winter began in late September. The serious damage to corn in Changji is 20% to 80%.

Control methods (1) After the harvest, the straw of the winter host should be treated in time, and it must be treated before the emergence of the wintering larvae. (2) Release the Trichogramma 2 to 3 times during the period from the initial stage of spawning to the stage of spawning, and put 1 to 20,000 heads per 667 square meters. (3) Spraying 25% of the chlorpyrifos No. 3 suspension 600 times solution or bt emulsion, and 200 ml of emulsion containing more than 10 billion spores per 667 square meters per gram can also be made into granules. (4) The use of Beauveria bassiana powder per square meter of straw with 100 to 10 billion microbial spores per 100 grams of powder, sprayed on the sputum before the corn sputum. (5) Mix 100 kg of fine soil with 0.5 kg of worm powder, apply it on the heart leaf, use 2.5-3.5 kg of bacterium for 667 square meters; (6) Combine the eggs with black light to match the field, and master the spawning In the case of quantity and hatching progress and field damage, when the rate of flowering leaves at the end of spring corn leaf is 10%, the treatment is carried out. If more than 20% or more than 30 eggs are laid, it needs to be prevented once more. At the end of the summer, the heart of the corn is protected once, and when the ear rate is 10%, or when there are 50 insects in the panicle, it should be prevented immediately. The medicament can be mixed with 50% of parathion emulsifiable concentrate 500 ml and appropriate amount of water and 25 kg of sieved cinder or sandstone. The granules are 1-2 g or 0.1% kungfu granules per plant. It can also spray 40% seven-star emulsifiable concentrate 800 times solution or 40% synergistic killing diced or 5% fulvain emulsifiable concentrate 2000 times solution, in addition to the retention fumigation method. The most important of the above methods is to reduce the wintering base of corn borer in order to effectively prevent the occurrence of corn borer and minimize the occurrence of insect pests.
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