What are the control methods for scale insects on peach trees

There are many species of scale insects that harm peach trees. The main species occurring in our province is the globose scale (Eulecanium kunoense), belonging to the order Homoptera, family Coccidae, genus Eulecanium. When its population is large, the affected branches are covered with dense layers of scale shells, causing poor tree growth; in severe cases, the leaves and small branches wither and die, and even the whole plant may die.

I. Occurrence pattern: The globose scale has one generation per year, overwintering as second-instar nymphs on the branches. It begins activity in mid-to-late March of the following year. Late April to mid-to-early May is the peak period of damage. From late April to early May, male insects emerge and mate with females; in May, females lay eggs beneath the scale shell. One female lays over 700 eggs, and at most 1400-1500 eggs. Eggs begin hatching from mid-to-late May, with the peak hatching period from late May to early June. The newly hatched nymphs crawl out from the mother shell and disperse onto small branches, leaves and fruits to cause damage; they begin overwintering in September.

II. Control methods: Chemical control is the main approach. When the nymphs are at the peak hatching stage and are dispersing in large numbers from the mother shell, spraying 50% malathion at 800-1000 times dilution, 40% omethoate at 800-1000 times dilution, or 80% dichlorvos at 1500-2000 times dilution all achieve good results. However, applying the pesticide after the nymphs have dispersed often fails to achieve the expected results. In addition, attention should be paid to protecting and utilising natural enemies such as the black-margined ladybird beetle.