Design and evaluation of an aerial spray trial with true replicates to test the efficacy of Bacillus thuringiensis insecticide in a boreal forest.
A field trial using true replicates was conducted successfully in a boreal forest in 1996 to evaluate the efficacy of two aerially applied Bacillus thuringiensis formulations, ABG 6429 and ABG 6430. A complete randomized design with four replicates per treatment was chosen. Twelve to 15 balsam fir (Abies balsamea [L.] Mill.) per plot were randomly selected as sample trees. Interplot buffer zones, > or = 200 m wide, adequately prevented cross contamination from sprays that were atomized with four rotary atomizers (volume median diameters ranging from 64.6 to 139.4 microm) and released approximately 30 m above the ground. The B. thuringiensis formulations were not significantly different (P > 0.05) from each other in reducing spruce budworm (Choristoneura fumiferana [Clem.]) populations and protecting balsam trees from defoliation but both formulations were significantly more efficacious than the controls. The results suggest that true replicates are a feasible alternative to pseudoreplication in experimental forest aerial applications.
Cadogan
Beresford L
BL
Natural Resources Canada, Canadian Forest Service--Great Lakes Forestry Centre, 1219 Queen Street East, Sault Ste. Marie, ON, P6A 2E5, Canada.
Scharbach
Roger D
RD
D028202:Abies; D000336:Aerosols; D000818:Animals; D001413:Bacillus thuringiensis; D009036:Moths; D010572:Pest Control, Biological / Q000379:methods*; D010935:Plant Diseases
D000336:Aerosols