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Trees in a Douglas-fir stand infested with western spruce budworm were
treated with a systemic insecticide to protect cone and seed production at
three locations in Montana during 1983. Treatments applied were (1)
acephate as an Acecap implant, (2) acephate as an Inject-A-Cide injection,
and (3) control. Potential cone-bearing trees were selected and then randomly assigned one of the above treatments. Treatments were applied from
mid- to late April. Cone buds varied from tight to recently burst. Data
collected were as follows: tree heights and diameters, cone damage and
infestation rate just after pollination, host tree defoliation from one
location, estimate of external damage on mature cones, green cone weight,
and seed per cone classified as full, hollow or damaged.
Rates of infestation and damage on the small cones were not different by
treatment. Foliage protection was between 56 and 74 percent. External cone
damage and cone weights improved with both acephate treatments. Seed yield
increased 69 to 82 percent for Acecaps and 65 to 84 percent for
Inject-A-Cides. The proportion of full, hollow, and damaged seed did not change between treatments. In budworm-infested Douglas-fir, both Acecaps
and Inject-A-Cides are an effective means to improve seed production. |
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