Control of Isatis indigotica in orchard

The green leafhopper has three generations a year, overwintering with eggs in the tissue under the epidermis of branches, and hatching into nymphs in April of the following year. After hatching, the nymphs are transferred to crops and weeds and propagate for 2 generations on these hosts. The third generation nymphs harm late autumn crops and vegetables, but generally do not harm fruit trees in summer. By late September, most of the green plants had withered, and the adults flew to the autumn vegetable garden and flew to the orchard in mid-late October to lay eggs on the branches of fruit trees.

Fruit trees suffer heavily when intercropping succulent crops such as cabbage, radish, carrot, sweet potato and so on in orchard. If these crops are harvested or removed as soon as possible, the damage to fruit trees will be significantly reduced. If the orchard is overgrown with weeds, the damage to the fruit trees will be aggravated.

> > Prevention and control methods:

(1) artificial control: brushing white agent on the trunk of young trees before spawning can prevent adults from spawning. The preparation method of whitening agent is: quicklime 25%, crude salt 4%, stone sulfur mixture 1% 2%, water 70%, and a small amount of insecticide can be added. Remove the weeds in the orchard in time, and it is best to turn them under the tree as fertilizer before the weed seeds mature.

(2) Agricultural control: young tree orchards should avoid intercropping succulent late-maturing crops such as Chinese cabbage, radish, carrot and sweet potato. If intercropping these crops, they should be harvested before the end of September.

(3) Pesticide control: when the number of occurrence is large, the adults should be sprayed before or at the initial stage of spawning in the first and middle of October. In addition to spraying on the tree, it should also be sprayed on the weeds between the tree rows. The commonly used agents are 20% fenvalerate EC 2000 times, 80% dichlorvos EC 1000 times, and 50% phoxim EC 1000 times.