Control Methods for the Dark Black Chafer in Peanut Fields

 The dark black chafer is the dominant population harming peanuts in the Xinyi area, and its larvae (white grubs) not only severely damage peanut pods, but also feed on crop roots in soybean, corn, sweet potato, Chinese medicinal herb, flower and nursery stock fields. In production, corresponding measures should be taken during the adult and larval stages according to the occurrence pattern of the dark black chafer.

1. Insert poisoned branches to trap and kill adults. The dark black chafer overwinters as larvae in the plow pan of peanut fields, pupates in early May, and emerges as adults (chafer beetles) in late May. After adult emergence, they lie dormant in the soil for about 13 days until the elytra harden, at which point they can emerge from the soil if soil moisture is suitable. The annual emergence peak is in mid-June, that is, on the evening of the second day after the first heavy rain following the wheat harvest, which is the best time to insert poisoned branches to trap and kill adults. That evening, except for rice fields, insert poisoned branches across the whole area, inserting 1 branch per 10 m square, once every other evening, for 3 consecutive times. Method for making poisoned branches: at 5 p.m., take elm branches or poplar branches, which the dark black chafer prefers to feed on, with branch length 1.5 m; dip the leaves into a 200-300 times dilution of 40% omethoate emulsifiable concentrate or a 200-300 times dilution of 50% acephate emulsifiable concentrate, then remove them, and insert them into the field before 7 p.m.

2. Chemical control of larvae. (1) At the peanut sowing stage, use the poisoned soil method for control. Per mu, use 1000-1200 ml of 40% phoxim emulsifiable concentrate or 150-200 ml of 48% chlorpyrifos emulsifiable concentrate, mix with 10 kg of dry fine soil, apply into the sowing furrow, and after sowing cover the seed with soil to bury the pesticide. (2) At the early flowering and young pod stages of peanut, before the white grubs reach the 2nd instar (2 cm long), use a 100 times dilution of 40% phoxim emulsifiable concentrate or a 300 times dilution of 48% chlorpyrifos emulsifiable concentrate, and spray it on the peanut root area when it rains. On sunny days, use a 500 times dilution of 40% phoxim emulsifiable concentrate or a 200 times dilution of 48% chlorpyrifos emulsifiable concentrate to drench the roots, applying 150-200 ml of the pesticide solution per plant.