Obscure scale is a serious pest of oaks, especially pin and willow. In California, it has been reported on apricot, peach and plum trees. Other common hosts are:
Obscure scale causes trees to develop a sparse, unhealthy appearance with small, off-color leaves.On close inspection, the bark may appear to be sprinkled with wood ashes and if scratched, numerous circular flat scales flake off. Small twigs and larger branches may die when an infestation is severe.
Obscure scale is named because of its size and color. The small, gray to dark gray insect blends with the natural color of the bark and can be difficult to see.
Treatment and Management
Obscure scale is difficult to control, but horticultural oil treatments in June and September should provide the most effective results. Adequate control may take a few seasons if the scale population is high. Fertilization with Arbor Green PRO® will increase tree tolerance to scale damage.