• Dimond, John B.
  University of Maine
  

Bacillus thuringiensis and B.t. plus chitinase were evaluated in controlling damage of the spruce budworm in northern Maine. Applications were made by helicopter to replicated small plots.

Similar levels of budworm population reduction were noted with both treatments, as compared to controls. Levels of population reductions were only moderate, however, it is believed that technical difficulties led to a major underestimation of this effect.

Data for foliage preservation were much stronger. A major protective effect on current foliage was demonstrated for the B.t. plus chitinase treatment, and this effect appeared as strong as that achieved with conventional insecticides when foliage preservation has been the goal, e.g. as with fenitrothion. The B.t. alone treatments showed levels of crown damage that were indistinguishable from that of control plots.