Control of Gall Production by Cooley Spruce Gall Adelgid on Spruce, 1997

Trials were conducted in Ft. Collins, CO on mature Colorado blue spruce in a shelterbelt planting at the Colorado State Forest Service Nursery, Ft. Collins, CO. Plots consisted of single branch terminals that hosted at least one overwintered female. Experimental design was a RCB with six replications. Treatments were applied to point of run-off on 9 May. Overwintered females had matured and were producing eggs, which hatched approximately 6 to 10 d subsequent to treatment, coincident with bud break. Each treated branch ultimately produced in excess of 10 new terminals. Plots were evaluated 10 Jun by noting the number and size of galled terminals on each treated branch. The size of galled terminals was rated on 1-5 scale: 5 for a fully formed gall, 3 for a partial/half gall, and 1 if only slight crooking was observed. For each plot, a gall intensity rating was determined by multiplying the no. of galls per terminal by size rating.