Pine needle scale is a small insect that attaches itself to pine needles and feeds on the sap. Each scale is protected by a hard, white covering about the size of a grain of rice. In heavy infestations the needles look flecked or coated with white, then turn yellow, and the tree begins to thin.
What it does to a tree
Pine needle scale does not usually kill a tree on its own. It weakens it, causing a gradual decline over several seasons, and a weakened pine is more vulnerable to drought and to bark beetles. We have treated pinyon pine on customer properties that showed significant feeding damage by mid to late summer.
How we treat
We treat pine needle scale with dormant oil, applied in late winter before the buds open. The hard covering protects the insect from most sprays applied during the growing season. Dormant oil does not need to get through that covering; it coats the scale and smothers it while the insect is overwintering on the needles.
The application depends on the weather as well as the calendar. The tree has to be fully dormant, the day has to be warm enough for the oil to spread evenly, and no hard freeze can follow immediately afterward.
What to look for
- White, oval flecks attached to the needles
- Yellowing needles, especially on the lower branches
- A thinning canopy over more than one season
All applications are made under Brookstone Outdoors' Colorado Department of Agriculture commercial pesticide applicator license.