Using Bacillus thuringiensis preparation, 8000 international units/ml per mu, diluted by 500~ 1000 times; The dose should not be too high.

If it is too low, focus on controlling larvae, especially 1~2 instar larvae; Avoid applying pesticide at high temperature, and do it in sunny afternoon or cloudy day.

When the temperature is lower than 65438 05℃, it is not suitable to apply pesticide; Spraying pesticides on the back of vegetable leaves.

The dosage is 1% emamectin EC 15-25ml/ mu, and 50 kg water spray. From the peak hatching period to the larval stage of Plutella xylostella eggs.

Spraying pesticides before the second age.

3.？ 5% fipronil suspension concentrate with dosage of 20-40ml/mu is mixed with 50kg of water for spraying. Spraying before the 2nd instar of Plutella xylostella eggs in the peak incubation period.

Spraying application.

4.？ The dosage is 10% chlorfenapyr suspension concentrate 35-50ml/mu, and it is sprayed after adding 50kg of water. At the peak of egg hatching or at the 2nd instar of Plutella xylostella larvae

It used to be sprayed.

Extended data

Plutella xylostella, alias: caterpillar, with two pointed heads. Migratory pests in the world mainly harm cruciferous plants such as cabbage, purple cabbage, broccoli, shepherd's purse, mustard, cauliflower, Chinese cabbage, rape, radish and so on.

Hazard characteristics: 1 instar larvae only feed on mesophyll, leaving epidermis, forming transparent spots on vegetable leaves, and "opening the skylight". 3 ~ 4 instar larvae can eat the vegetable leaves into holes and nicks, and in severe cases, eat the whole leaves into nets. At seedling stage, the central leaf is often damaged, affecting the core. It damages the young stems, young pods and seeds of seed-preserved plants.

Introduction to prevention

1, rational distribution of agricultural prevention and control, avoiding continuous cropping of cruciferous vegetables as much as possible to avoid recurrence of pests, strengthening seedling field management and timely prevention and control. After harvest, if the residual plants are treated in time, a large number of insect sources can be eliminated.

2. Physical control of Plutella xylostella has phototaxis. In the insect occurrence period, black light can be placed to trap and kill Plutella xylostella to reduce the source of insects.

3, biological control using biological pesticides, such as BT emulsion 600 times solution can make the diamondback moth larvae susceptible to death, diamondback moth nuclear polyhedron? 600 times the venom can kill Plutella xylostella larvae.

4.700 times of clofenuron, 2,000 times of 25% chlorpyrifos, 1000 times of 24% valium (be careful not to overdo this medicine to avoid phytotoxicity, and do not use pesticides containing phoxim and dichlorvos to avoid "burning leaves") and 5% carbendazim 2000? Double solution for prevention and control, or spray with Fujiang (10.5% phenylurea) 1000- 1500 times solution. Pay attention to alternate or mixed use to slow down the emergence of drug resistance.

5. Spraying with "Hanke140"10 ~ 15ml has a special effect, and it can take effect in 1 ~ 3 hours, and the control effect can still reach over 90% after15 days; Generally, spraying 1 ~ 2 times can realize pollution-free vegetable fields.

References:

Baidu encyclopedia-Plutella xylostella