Occurrence and Control Methods of the Pear Yellow Pink Aphid

I. Distribution and Damage. It occurs commonly in the northern regions of China and only damages plants of the genus Pyrus. This pest mainly damages the fruit by adults and nymphs gathering at the calyx depression of pear fruits to feed, and it also damages other parts. The surface of the damaged peel initially shows small yellowish, slightly sunken spots, which later gradually turn black and expand outward in wavy rings, often forming cracked large black scars and even causing fruit drop.

II. Occurrence Pattern. The pear yellow pink aphid generally has 8 to 10 generations per year, overwintering as eggs on fruit spurs, in bark crevices, under the raised bark damaged by the pear bark miner moth, and on debris attached to branches and trunks. The eggs begin to hatch during the pear tree flowering period the following year. The nymphs feed on sap at the tender tissues under the bark, grow and develop, and lay eggs to reproduce. In June they move to the calyx depression and stem depression of the fruit, and then spread to the fruit surface and other places. Damage is most severe in mid-August when the fruit is approaching maturity. In August to September, sexual aphids appear; after mating, the females and males move to fruit spurs, bark crevices and other places to lay eggs and overwinter. In orchards where fruit bagging is practiced, because the inside of the bag is shaded and humid, the paper bag becomes a protective umbrella; the larvae sneak in from the bag opening at the fruit stalk, making it difficult for pesticides to reach them and easily causing damage. Bagging growers should pay attention to this.

III. Control Measures. (1) In winter and spring, carefully scrape off old bark and raised bark, and remove debris attached to the trees to kill overwintering eggs. (2) Before pear trees bud in spring (mid to late March), spray 3 to 5 degrees Baume lime sulfur mixture to kill overwintering eggs; spraying should be thorough and meticulous. (3) When 70% to 80% of the flowers of Yali pear have fallen, this is exactly the nymph hatching period and the key period for control; spray once with 2.5% imidacloprid emulsifiable concentrate at 3000 times dilution for control. (4) Spray once each before bagging the pears and in June with 8% acetamiprid emulsifiable concentrate at 2000 times dilution or imidacloprid emulsifiable concentrate at 3000 times dilution. (5) For bagged pear orchards, choose high-quality paper bags that are not easily damaged, and tie the bag opening tightly without injuring the fruit stalk to prevent the yellow pink aphid from sneaking into the bag. Insecticidal bags may also be used, or a cotton ball with pesticide may be clipped at the bag opening.