European red mite

Insect

European red mite

Panonychus ulmi (Koch)

Acari: Tetranychidae

Distribution: Widespread and a major pest in most fruit-growing states and provinces in eastern North America.

Photos

The adult female is dark red and has silky hairs on its back borne on raised whitish tubercules (A). The male is smaller, lighter in color, and has a pointed abdomen (B). The mites feed mainly on the undersurface of the leaves. Eggs are red and are laid principally on the underside of leaves. Overwintering eggs are darker in color, and are laid between mid-August and the beginning of October on spurs, in bark crevices (C) and in the fruit calyx.

Crops Affected: grapes

Damage

Mites hatch in the spring from tiny, spherical eggs laid around cane nodes and under loose bark. These eggs can be detected by scouting in early spring. Although several generations can occur each season, populations rarely increase enough to cause significant damage because predatory mites usually prevent their growth.
Crops Affected: apples, cherries, peaches, pears, plums

Damage

Attacks foliage of apple mainly, and other tree fruits less often. Leaves become speckled under light infestation. Bronzing occurs during serious infestations (D; healthy foliage on left, damaged foliage on right). A severe attack can reduce fruit growth and cause preharvest drop on certain varieties.

Management

Spray a delayed dormant oil when buds are showing green tissue but before pink bud, to kill overwintered eggs; preserve predators of mites. Monitor motile forms on leaves after fruit set; use miticides (based on thresholds) or horticultural mineral oil to reduce numbers during the summer period. A selective pesticide program may allow biological control by predator mites, glassy-winged mirid bug (Hyaliodes vitripennis) or Stethorus punctum.