Symptoms and control of soybean diamondback moth

(Agricultural Wealth Network) Big bean moth alias soybean moth, mainly harm edamame, cowpea and other leguminous vegetables.

Harm symptom bean moth to larvae feed leaves, young larvae eat into mesh and notch, after the third instar larvae can eat all bean leaves, so that the plant can not bear pods, for the yield of great impact.

The peak period of adult oviposition is from the middle and late July to the first ten days of August, the peak period of larva occurrence is from the late July to the last ten days of August, and the pale yellow mature larvae overwinter in the first ten days of September.

Adult life habits: adults day out night, black light has a strong tendency. Evening activity, strong flight, strong mobility. They mate at night and lay eggs 3 days after mating. The eggs are mostly scattered on the back of bean leaves. Generally, 1~2 eggs are laid on one leaf. The eggs can hatch into larvae about 7 days after mating. Larvae: Larvae have backlight sex, more in the day on the back of leaves or branches, feeding at night strong, cloudy days can feed all day. 1~2 instar larvae eat little, generally do not transfer damage, after 4 instar has the habit of transferring damage, 5 instar larvae eat sharply, its food intake accounts for more than 90% of the total food intake. The larval stage lasts 30 - 35 days.

The drought condition was unfavorable to the occurrence of the bean moth. The silted land with dense plant growth, low-lying and fertile soil was more serious, and the early maturing soybean varieties were more seriously affected. During pupation and eclosion, if rain is moderate, occurrence is heavy. Too much rain delays the onset.

Control methods: the use of adults strong phototaxis, set up black light trap adults, can reduce the number of eggs dropped in the bean field, reduce harm. Pesticide control: the suitable period for controlling the larvae of bean moth should be grasped before the third instar, and 4.5% beta-cypermethrin 1500~2000 times solution or 50% phoxim EC 1500 times solution should be sprayed per mu, and 50 kg solution should be sprayed per mu. Since larvae have the habit of lying down during the day and emerging at night, the spraying time should be selected after 5 pm.