Gansu Farmers Network - Gansu Farmers Daily October 27 (expert Meng Tienan) consultation: I am a farmer in Lintao, the grubs in the astragalus field have a serious occurrence, and the grubs are larger, as big as small fingers, how to prevent it?
Answer: According to the situation reflected by this farmer friend and the author's understanding of this area, the preliminary judgment is that the grub species in the astragalus field are the larvae of the small cloud-spotted gill turtle. The vertical activity habit of grubs is mainly related to the temperature of the soil, and the optimal soil temperature for crop tillage activity is on average 13 °C to 18 °C. From late October to early November, when the soil temperature continues to drop, it is submerged into a soil layer of 30 to 50 cm for wintering.
Prevention and control methods:
1. Agricultural measures. Combined with measures such as deep turning of thin rakes, crop rotation and stubble, and weeding in middle cultivation, a large number of grubs in the soil can be killed.
2. Artificial prevention and control. Every year, during spring ploughing and autumn ploughing, grubs are picked up with the plough and can be used as poultry feed.
3. Pharmaceutical prevention and control. Because grubs live in the soil all their lives, the key to the prevention and control of the drug is that the agent must be applied into the soil in order to receive a better control effect. (1) Pharmaceutical seed mixing: This is the most economical and simple and effective method for controlling grubs. Commonly used agents are octyl thion, chlorpyrifos, etc., weigh the agent according to 0.2% of the weight of the seed, dilute it with an appropriate amount of water, mix well with the seeds and pile up for half a day after sowing. (2) Soil agent treatment: before crop sowing, use 15% poison xin granules 300 to 500 grams per mu, mix the soil and spread it evenly on the surface, and then mix it into the cultivated soil. Or use 500 grams of 50% octyl thiophosphorus emulsion per mu, dilute with water and mix well with 50 kilograms of fine sand soil, sprinkle on the surface, turn into the soil and then sow seeds. (3) Poison sand treatment sowing ditch: mu with 50% octyl thiophosphate emulsion 500 grams, diluted with an appropriate amount of water, mixed with 20 kg of fine sand soil and applied to the sowing ditch, and then sown. Or use 10% exterminated phosphorus granules 4 to 5 kg per mu, sprinkle medicine and cover the soil after trenching, and then cover the soil after sowing. (Provincial "12316 Sannong" plant disease and pest expert Meng Tienan)