A scale insect, known as San Jose scale, is a common pest of roses, apples, plums, nectarines, apricots, alder, almond, arborvitae, ash, beech, birch, blackberry, ceanothus, cherry, chestnut, elm, fig, eucalyptus, grape, hibiscus, orange, peach, persimmon, raspberry, walnut, willow, and the list goes on and on.This scale is considered an omnivore in its feeding habits. I point this out because if you have San Jose scale on your rose bush, there are most likely infestations on other plants in your landscape.
While plants are dormant, or nearly so, is the perfect time to treat for control of this nasty little pest. Spray the plants with dormant oil according to directions on the label. The plant should be completely covered – all surfaces wet.
There are many species of scale, which can attack many species of landscape plants and fruit trees on the Central Coast. Therefore, check all the plants in your yard, especially those where you notice ant activity. Ant activity on a plant is often a signal that scale insects are nearby.