by Nanette Londeree, Master Rosarian
SIGNS
Eight legged, oval shaped adults ranging in color from red and brown to yellow and green depending on the species and the season, particularly June through September
SYMPTOMS
Stippling or yellowing of leaves; leaves look gray or dry
Leaves turn yellow and drop off
Webbing on undersides of leaves
Eggs on undersides of leaves
CAUSE
Species in the Tetranychus genus – the two-spotted spider mite and the Pacific spider mite
OPTIMAL CONDITIONS
Low rainfall areas
Warm summer temperatures above 70°F
Dry plant foliage
Dust and dirt on leaf surfaces
TREATMENT
Prevention:
Maintain good garden sanitation
Remove fallen leaves, branches or fruit, as well as weeds that may serve as a host
Periodic hosing of plants with a forceful jet of water, including the undersides of leaves
Elimination:
Use selective materials, preferably insecticidal soap, horticultural oil or neem oil
For additional information on management, visit the UC IPM website
GOOD GUY / BAD GUY?
A really bad guy, especially in dry weather when a plant can be completely defoliated in a matter of days