Soybean borers larvae into the soybean meal in the larvae to feed on the beans, mainly affect the quality of soybean, and also have a certain impact on the yield.
Soybean borers occur one generation in a year. They use mature larvae for wintering in the soil. In mid-to-late July, winter larvae become eclosion and fly. They migrate to soybean fields and they stay lurking in the morning. They start their activities after 3-4 pm, and they are late. Stopped after the bean plant. When the adult enters its peak period, the male and female moths can see each other on the edge of the bean field before sunset and become a moth phenomenon. Adult eggs are prolific on soybean cakes, and a few are produced on petiole, collateral or main stem, and usually produce one on one tablet. The larvae crawled on the pods after hatching, looking for leeches, and finally gnaw through the pods near the side of the pods and drilled into the pods. At this time, when the soybeans are in the tender period, the larvae start to eat the beans in the pot until the soybeans mature. The mature larvae sew a small hole from the pods, dislocate, fall on the ground, and drill into the soil to prepare for winter. .
Adults have phototaxis. Spawning is markedly selective. Eggs are generally spawned on hairy pods and sparsely laid on hairless pods. In addition, adult spawning is related to the maturity of soybean meal. Young pods have more eggs, while yellow pods have fewer eggs.
High temperature and high humidity in the soil are conducive to phlegm and feathering. When the soil temperature of 1 to 10 cm deep rises above 20°C, the intra-land larvae begin to move up and down. Low or high soil moisture content is not conducive to phlegm and feathering.
The growth of adults in the fields is related to rainfall. Adults emerge in the soil but have poor ability to exhume. Rainfall not only lowers the temperature and affects the activities of adults, but also rainstorms can block the adult emergence holes, making it difficult for adults to unearth, thereby reducing the number of adults.
The farming system has a great influence on the occurrence of soybean borer. Under the same conditions, the continuous cropping of soybean crops was more severe than the cropping of soybean crops in the rotation. Generally, the crop rotation rate was lower than the continuous cropping rate by more than 40%. The intercropping of high-crop crops such as soybean and corn objectively enlarges the distribution area of ​​soybeans, and it is not convenient for crop rotation. Even if it is replaced, it is too close to last year's soybean meal to facilitate the migration of adults after emergence.
In addition, the varieties of resistance and insect repellent effects, the number of natural enemies occurred, etc. have a certain impact on the occurrence and damage of soybean borer.
Control methods:
1. Long-distance rotation: Among the cultivated crops, soybean borer only harms soybeans, and at the same time its wintering place is bean ground, and the flying ability of the adult is very weak and cannot fly long distances. Therefore, the implementation of a relatively long distance rotation can reduce its damage.
2. Deep-sweeping the soil: After soybeans are harvested, they should be turned over in time to increase the mortality rate of overwintering larvae. For the spring wheat field sown by soybean meal, after the summer harvest, the larvae and cockroaches that will be larvae in the topsoil will be turned to the ground so that the earthworms cannot be feathered, or the adult eclosion cannot be grounded and die. Increase larval mortality.
3. Control of chemicals: In the middle and late July, the field will be sprayed with fumigation agent such as phoxim that has a large odor to prevent larvae from fleeing to the soybean field; in the middle of August, the larvae will be controlled with pyrethroid pesticides, for example, 2.5% per hectare. Kung Fu EC 0.225 to 0.3 liters; or 2.4% to 0.36 liters per hectare with 2.5% dichlormophilic emulsion sprayed on water.
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