Brassica napus larvae are serious pests in the rapeseed production, which affect the production of important pests, retransmission year, resulting in rapeseed production by 2 to 40%.
The rape stem weevil takes place one generation per year, and the adults spend winter in the rhizosphere of the earth seam. In spring and early March, the adults laid eggs and spawned on the base of rape stems. The larvae harmed the heaviest larvae, resulting in enlarged, twisted, cracked, deformed, dwarfed, clustered stalks of rape, and reduced branches and pods. When the wind blows easily, the plants are seriously affected by the growth and solidification. The yield loss of rapeseed is serious. At present, the temperature has started to rise, and the excavation activity of the stem caterpillar has increased, and it has entered the initial stage of the occurrence of damage. It is also a critical period for the prevention and control of this insect. Once it is missed, it is difficult to control it. Therefore, it is recommended that all localities immediately implement prevention and control to ensure the normal growth of rapeseed.
Control methods: Pharmacy can use 2.5% deltamethrin EC 15 ~ 20 ml / mu or 48% chlorpyrifos EC 2000 times with Sorry Boron 2000 times spray. Or 10% Phosphate granules 1 to 1.5 kilograms per mus. Due to the long period of excavation of rapeseed's stalks, it is better to control it twice every 7-10 days.
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