The bollworm occurs four generations a year. The third and fourth generations harmed cotton and also harmed corn, sorghum and other crops. It was observed that three or four generations of H. armigera occurred from late July to early September. In July and August, most of the eggs were produced on the frontal side of the young leaves and on the side of the leaves and on the buds of the buds. A small part of the eggs were found on the leaves, petioles, and flowers. Prevention and treatment of cotton bollworm must first do a good job in forecasting. The method is: Every 667 square meters of willow branches put ten bundles, each bundle one, about small finger thick, one meter long, bundled in the lower end, upside down in the cotton field, about 20 centimeters higher than the cotton, catch moths every morning, At the same time, monitoring the occurrence period, so as to grasp the favorable opportunity to eliminate the larvae before harming Lei Ling bell. Therefore, during the spawning period of cotton bollworm, the cotton field was surveyed once every 3 days, 50-100 strains were inspected each time, and the number of eggs and larvae was carefully searched. According to different characteristics of different generations, different methods of energy conservation are adopted. When the third generation of H. armigera occurred in July and August, there were not many eggs in raining, but the spawning lasted for a long time. If eggs were sprayed during the period of egg production, eggs born prematurely were hatched and infested. At the same time as the eggs, the number of larvae is emphatically examined. When there are 100 larvae and 5 heads, spraying control is necessary. At this time, the cotton plant is tall and spawning is dispersed. It should be combined with spraying and dusting, and it should be treated in case of rain. When the fourth generation of cotton bollworm occurred in August and September, the cotton strain began to age, the temperature was low, the temperature difference between day and night was large, the hatching rate of eggs was low, and the mortality of first-instar larvae was high. The second-instar larvae (second instar larvae body length 4) should be emphatically examined. The amount of ~ 5 mm) should be sprayed when 100 plants have 5 second-instar larvae. Focus on the prevention of late-maturing plots, to do a good job of chemical control, the general cotton field to do a good job pruning, remove invalid buds, bring out of the field, can eliminate a large number of eggs. Due to the timing of prevention and cure when insecticides are sprayed, the cotton bollworm 3 causes more than the larvae for a long time, the control effect is not good, and it should be timely and manually captured to reduce the hazard.
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