Control of chestnut gall wasp

Chestnut gall wasp DryocosmuskuriphilusYasumatsu belongs to the family Cynipidae, also known as chestnut tumor wasp. Chestnut producing areas are widely distributed, causing damage to larvae in the new buds of chestnut trees. When the chestnut buds germinate in spring, the injured buds can not germinate, gradually expand and form galls, and sometimes there are abnormal leaflets on the gall tumor. In severe cases, the tree is weak, which can cause branches or the whole plant to die.

The shape of the adult is 2.5ml 3 mm long; the head and abdomen are dark brown; the chest is dilated, dark black and shiny; the wings are transparent, the wing veins are black, and the feet are yellow with well-developed hind feet. The larvae are ca. 2.5 mm long, milky white, fusiform, stout, legless.

The law of occurrence occurs in one year and one generation. The first instar larvae overwintered in the host bud. When the chestnut tree shoots in spring, a small gall tumor appears on the branches and leaves of the new shoot, and the larvae mature in late May and pupate in the gall tumor. In the first ten days of June, the adults Eclosion, bite through the gall tumor to go out and lay eggs, the eggs hatch into larvae and do harm in the bud for a period of time, and form an oval chamber in the affected area, and begin to overwinter in late September. The galls were enlarged in March of the following year. The natural enemies of chestnut gall wasp are mainly parasitic wasps with many species, mainly Chinese long-tailed wasp.

The control methods (1) in winter, combined with pruning to remove the branches with galls, improve the ventilation and light transmission conditions in the crown, and strengthen the cultivation management to enhance the tree potential and promote the growth of new shoots. Heavy pruning can be taken in the seriously damaged chestnut forest, except for the dormant buds at the base of the branches, the rest can be cut off, and the results can be restored after 1 year. (2) chemical control. The severely damaged chestnut forest can kill a large number of adults by spraying the crown with 50% fenitrothion EC, 40% dimethoate EC 1500 times and 80% dichlorvos emulsion 2000 times in early June. In addition, in the chestnut forest with dense canopy, dichlorvos fumigant can also be used during the peak period of adults.

Another species of chestnut gall wasp (DiplolepisjaponicaAsh.) forms galls on young shoots, and its control method is the same as that of chestnut gall wasp.