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Panonychus ulmi (ERM),Tetranychus urticae (TSSM)

 

European Red Mite

Two-spotted Spider Mite

Overwintering stage

Eggs

Orange-colored adult females

Overwintering sites

Overwintering eggs are laid on twigs and small limbs, especially in the crevices, and roughened bark of apple trees

Orchard ground cover

Timing of egg-hatch

Egg hatch begins at Tight Cluster, is about half complete by Pink, and is complete by Petal Fall.

With the arrival of warm weather in the spring, these mites leave their places of hibernation and start wandering about looking for food plants.

Feeding sites during spring

Young mites move to newly opened leaves where they feed, mature, and reproduce.

Weeds and grasses (mites move to fruit trees (underside of leaves) in the summer

Early-season monitoring

Two-spotted spider mites should be monitored and managed in much the same way as European red mites. Counts of the two species should be combined to determine whether thresholds are exceeded.

Monitoring of European red mite eggs can be done by visually inspecting the bases of twigs and spurs on 5 to 10 selected trees with a hand lens. Look for clusters of tiny (less than 1/50 inch), red spheres. See pictures below.

Mite injury during the weeks following Petal Fall can damage fruit crop. Monitor mite populations by examining underside of fruit cluster leaves through May and June. Action threshold is 1-2 motile (not eggs) mites per leaf or 30% of leaves with one or more mites

Early-season management

Oil is recommended at the 2-3 gal rate during the dormant period. Use 2 gal rate until Tight Cluster. Reduce to 1 gal rate from Tight Cluster to Pink. Oils can be safely applied up to the pink stage.  Since fruit tree architecture includes many cracks and crevices as well limbs and twigs that exponentially increase surface area, coverage to the point of drip is key. 

 

Do not use oils within 24 to 48 hours before freezing temperatures, or if temperature is below 35F following a freeze. Do not apply within 10 to 14 days of sprays containing captan or sulfur.

Chemical control

A selective miticide program that is based on thresholds may allow biological control by predator mites.

2-spotted spider mite (photo: Art Cushman, USDA Systematics Entomology Laboratory, Bugwood.org))
2-spotted spider mite (photo: Art Cushman, USDA Systematics Entomology Laboratory, Bugwood.org))
ERM overwintering eggs (Photo by Jack Kelly Clark)
ERM overwintering eggs (Photo by Jack Kelly Clark)
ERM overwintering eggs (Photo by Jack Kelly Clark)
ERM overwintering eggs (Photo by Jack Kelly Clark)
ERM overwintering eggs (Photo by Jack Kelly Clark)
ERM overwintering eggs (Photo by Jack Kelly Clark)