Control Methods for Spider Mite Damage on Cherry Blossoms
How to control the damage caused by spider mites to cherry blossoms?
The spider mites that harm cherry blossoms are mostly hawthorn spider mites, also known as hawthorn red spider mites. Spider mites mainly damage cherry blossom leaves. In early spring, the adults and nymphs gather on the undersides of leaves, piercing their mouthparts into the leaf tissue to suck sap, causing the damaged leaves to show chlorotic spots; in severe cases, the leaves scorch and drop early.
The female adult of the hawthorn spider mite is 0.5 mm long, oval in shape, with a total of 26 setae on its back. The body is red, with winter and summer forms: the winter form is bright red with a silky sheen; the summer form is red when molting and turns dark red after feeding. The male adult is 0.4 mm long, with a tapered rear end; the body is light yellow-green when newly molted, then turns green and orange-yellow. There are two dark green stripes on each side of the back. In North China, the hawthorn spider mite has 5 to 9 generations per year, mainly overwintering as fertilized female adults in bark crevices of branches and trunks and in soil crevices around the plants. The overwintering female adults begin activity in mid-to-late April of the following year, damaging buds and leaves. July to August is the peak period of occurrence, when the damage is most severe.
Measures to control the hawthorn spider mite: First, clean the garden to eliminate overwintering mite sources. Second, before buds sprout in early spring, spray 3-5 degrees Beaume lime-sulfur mixture to control overwintering female adults. Third, chemical control should be timely: detect early and spray early. Options include 20% dicofol emulsifiable concentrate at 1500 times dilution, 73% propargite emulsifiable concentrate at 2000-3000 times dilution, etc. When spraying, make sure to also spray the undersides of leaves. Fourth, protect and utilize natural enemies such as predatory mites (Stethorus ladybirds) and spiders.