From mid-July to early September, the third and fourth generations of cotton bollworms are endangered. Due to the increase in the percentage of interplanted cotton fields and the late development of this year, the second generation of H. armigera has a large amount of debris, and generally more precipitation in July and August. The resistance of insect-resistant cotton to the growth stage is greatly reduced in the middle and late stages of growth. According to the author's multi-year survey, the majority of spring cotton plants in the period from mid-July to early September have become ageing, the amount of eggs laid by the bollworm is relatively low, and the hatching rate is also relatively low, while the interplanting cotton mostly matures later and the cotton plants are younger. The tenderness was very favorable to the feeding of the bollworm, so the amount of eggs laid and the hatching rate of the eggs were 45.2% and 53.6% higher than that of the pure cotton field. Therefore, late-maturing cotton fields (most interplanting cotton fields and a few late-spring pure cotton fields) are the focus of the third and fourth generations of cotton bollworms.
Mastering the laws of egg movement
Grasp the rules of spawning and pay attention to the application site. Many bollworms produce eggs on the top of cotton plants, on the top leaves of fruiting branches, on buds and stalks. Therefore, the focus of application should also be on these sites.
Grasp the laws of incubation and pay attention to timely prevention and treatment. The hatching rule of the bollworm is: the head of the egg is white, yellow on the second day, black on the third day, hatch on the fourth day, and the growth point is damaged on the second day after the hatching of the eggs, and the migration damages the young buds on the fourth day. Therefore, the appropriate period of prevention and control should be after the hatching peak of the eggs, most eggs become black or before the migration does not migrate.
Grasp the law of feeding, pay attention to the application time. It was observed that most of the bollworms were active at 8 to 11 o'clock and after 15 o'clock, and rarely at high temperatures from 12 to 13 o'clock. Therefore, it is better to apply the drug at the time of its activity. Pay attention not to apply pesticide at high temperature, because the liquid is volatile and decompose at high temperature, which not only makes the operator poisoned, but also reduces the control effect. Do not apply the drug when there is dew in the morning, because the concentration of the liquid is diluted and the adhesion becomes poor. , Poor efficacy.
Trapping eggs and spraying pesticides
Cut poplar branches and trap adult cotton bollworms. The fresh poplar branches with leaves will be bundled into 6 to 8 sticks. About two meters high, they will be inserted into the cotton fields before and after the evening and insert 10 to 15 per mu. When the adults of the cotton bollworm come out during the night, they smell the odor emitted by the poplar branches and they will penetrate into the branches. From the second day after the insertion, before the daytime sun did not come out, the branch pulled up a set of plastic belts to shake it, collecting the hidden moths and then killing them. After the killing, put the branches on the cotton line to prevent the sun, and then insert the sticks at dusk. Every 5 to 6 days for a new one, until the end of August.
Using this method, the occurrence period of the cotton bollworm can be measured based on the number of eggs and larvae found, and the favorable timing of exterminating the eggs can be grasped, and the larvae can also be eliminated before the cotton bud bell is harmed.
The application of calcium superphosphate solution drives the concentrated spawning of cotton bollworms, greatly reducing the control area. In the spawning period of cotton bollworm, add 1% to 2% of superphosphate soaking and clarifying solution in the insecticide solution and spray it. Spray 6 lines each at intervals of 4 lines. ~70 kg, so that the osmotic acid and phosphorus produced by the sprayed cotton plants are combined to form calcium oxalate, which causes it to lose the effect of attracting bollworm, and drives the cotton bollworm to concentrate on the non-sprayed cotton plants to facilitate egg mass destruction, thus greatly destroying reduce workload. The supernatant liquid soaked with superphosphate can also be sprayed separately, and the insect repellent has the same effect. It is worth noting that spraying calcium superphosphate can harden the eggshell of the cotton bollworm, causing the larvae to die without shelling. In addition, the application of calcium superphosphate solution has an effect of increasing production.
Artificially sterilize eggs and catch insects. As the older larvae of H. armigera have stronger drug resistance and poor drug killing effect, they are combined with field management two days after spraying, and the artificial larvae take advantage of the timing of morning and rainy days for artificial capture.
Use pesticides on the road to prevent and control. While using the above-mentioned prevention and control measures, field investigations should be conducted. If the three generations of H. armigera reach 15 larvae and the fourth-generation H. armigera reach 8 to 10, the spraying should be promptly controlled. At present, the following pesticides with good control effect can be selected: 1000 times of 25% diafenthiurin EC, or 1000 to 1500 times of 35% EC, or 1500 times of 20% methomyl EC, or 1500 times of 2.5% CIPO. , or 2.5% Emu EC 1500 times, or 10% Ester 2000 times. These pesticides have good control effects on many pests such as Helicoverpa armigera, Blind mite, Aphid, Red spider, Corn borer, and Bridge insect. The above-mentioned pesticides should be alternately used for rotation, and one pesticide is preferably used only once to prevent the insects from developing drug resistance, so as to facilitate the improvement of the control effect.
Pay attention to details to improve efficacy
Note that several pesticides are alternately used in order to prevent the cotton bollworm from developing resistance to the drug.
Pay attention to pesticide reconstitution to delay drug resistance of cotton bollworm, and be careful not to mix acidic and alkaline pesticides.
Note that according to the pesticide use instructions multiples with sufficient concentration, can not be arbitrarily increased or decreased.
When the second-generation cotton bollworm is controlled, 40-50 kg per mu are used; when the third or fourth-generation cotton bollworm is controlled, the liquid medicine per mu is 80-100 kg.
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