Rape is a common field-type economic crop in our daily life. In the process of rapeseed cultivation, some pests and diseases will inevitably occur. Among them, rapestack is a common pest. This article will introduce the control techniques of rapeseed aphids.
Characteristics of the damage : the larvae are drill-bit pests, which damage the heart leaves and leaves of the seedlings of the seedlings. The damaged seedlings stop growing or wilting due to the destruction of the growth point, resulting in lack of seedlings and ridges. Cabbage and cabbage can not bear the ball, cover the heart, and can spread soft rot, leading to reduced production.
Morphological characteristics : adult body length 7mm, wingspan 15mm, taupe; front wing with 3 white horizontal ripples, a dark brown kidney-shaped spot in the middle, with white edges; rear wings gray-white. The egg is about 0.3mm long, elliptical, flat, irregularly textured on the surface, with a pale yellow color, and later red spots, orange-yellow before hatching. The mature larvae are 12-14 mm in length, black in the head, pale yellow in the ankle, yellow-brown in the front and back, and there are inconspicuous taupe vertical stripes on the back of the body. There are hairy tumors in each section, and 6 pairs in the middle and back chest. There are 8 front rows in the abdomen and 2 in the back row. The carcass is about 7mm long, yellow-brown, and the wing buds reach the trailing edge of the fourth abdominal segment. The five longitudinal lines on the back of the abdomen are faintly visible. The end of the abdomen grows 2 pairs of thorns. The center 1 pair is slightly shorter and the ends are slightly curved.
Habits of life : 3 to 4 generations in Beijing and Shandong, 6 to 7 generations in Shanghai and Chengdu, and 9th generation in Liuzhou, Guangxi. The old larvae are spliced ​​with soil and dead leaves on the ground to make silkworms overwinter (a few蛹 Overwintering). The winter larvae of Hunchun are buried in the soil of 6 to 10 cm deep. The adult phototaxis is not strong, the flying power is weak, and the eggs are scattered on the young leaves of the vegetable seedlings, and the average female can produce about 200 grains. The egg development period is 2-4 days. The hatching larvae of the newly hatched larvae are harmful, the tunnel is wide and short; the leaf surface is worn after the 2nd instar; the 3rd instar is fused with the heart leaf, and the heart is eaten, so that the heart leaves die and the heart leaves can no longer be extracted; 4-5 years old can be heart The leaves or petiole are inserted into the stalk or root, the pupil is prominent, the pores are adorned with filaments, and the moist worms are discharged. The victim is dead or the petiole is rotten. The larvae can be transformed into 4-5 strains. The larvae are 5 years old and mature, and they are phlegm in the soil near the vegetable roots. From May to September, the larval development period is 9-16 days, 蛹4-19 days. This insect likes high temperature and low humidity environment. The autumn cabbage planted in Beijing from August to September is in the true leaf stage of 3-5 seedlings. The temperature is about 24 °C, and the relative humidity is about 67%, which coincides with the larval growth period and the most serious damage.
Control methods : (1) Agricultural control First, ploughing the land, can eliminate some of the wintering larvae in the topsoil or dead leaves, and reduce the source of insects. The second is to adjust the sowing date so that the 3 to 5 true leaf stage of the vegetable seedlings is staggered from the high growth period of the vegetable. Third, proper irrigation and increase the humidity in the field can not only inhibit pests, but also promote the growth of vegetable seedlings. (2) Chemical control This insect is a drill-bit pest, so the spraying control must grasp the adult germination period and the larva hatching period. It can be used to kill cockroach (21% synergistic cyan·horse emulsifiable concentrate) or 40% acetobutyl Chrysanthemum EC 3000 times, 2.5% Kung Fu EC 2000 times, 20% anti-sweeping cream or 2.5% Uranus EC 3000 times, 20% chrysanthemum 2000-3000 times, 10% chrysanthemum 1500 - 2000 times liquid, the effect is better.
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