Occurrence and control of pear yellow powder aphid

1. Distribution and damage are common in northern China, and only harm to pear plants. The insect is mainly harmful to adults and nymphs in the calyx depression of pear fruit, as well as in other parts. The damaged pericarp showed yellow slightly sunken spots at the beginning, and then gradually became black, expanding around with wavy rims, often forming cracked black scars or even falling fruit.

Second, the occurrence regularity of pear yellow powder aphid generally occurs for 8 to 10 generations a year, overwintering with eggs under the warped skin and on the branches damaged by fruit platform, bark cracks, pear subcutaneous moth and branches. The pear trees begin to hatch at flowering stage the following year. The nymph takes sap from the tender tissue under the bark, grows and develops, and lays eggs. It transferred to the calyx depression and stem depression of the fruit in June, and then spread to the fruit surface, and the damage was the most serious when the fruit was nearly ripe in the middle of August. Sexual aphids appeared from August to September. After mating, males and females were transferred to fruit platforms, bark cracks and other places to lay eggs and survive the winter. In the orchard where fruit bagging is carried out, the paper bag becomes a protective umbrella because of avoiding light and high humidity in the bag. when the larvae sneak in from the bag mouth of the fruit stalk, it is difficult to receive medicine and is easy to cause harm, which should attract the attention of bagging growers.

Third, prevention and control measures (1) seriously scrape off the old bark and warped bark in winter and spring, and remove the residue on the tree in order to kill the overwintering eggs. (2) before the pear tree germinates in spring (mid-late March), the stone sulfur mixture of 3-5 Baume is sprayed to kill the overwintering eggs. The spraying should be considerate and meticulous. (3) 70% ~ 80% of the flowers of Yali pear is the nymph incubation period, which is the key period of control. 3000 times of 2.5% imidacloprid EC can be sprayed once for control. (4) 2000 times of acetamiprid EC or 3000 times of imidacloprid EC were sprayed on pear trees before bagging and 6 months respectively. (5) the bagged pear orchard should choose a high-quality paper bag that is not easy to be damaged, and fasten the mouth of the bag strictly without damaging the fruit stalk to prevent the yellow powder aphid from sneaking into the bag.