• Maclean, David A.
  Canadian Forest Service
  
• Hunt, Tony L
  New Brunswick Department of Natural Resources and Energy
  
• Eveleigh, Eldon S
  Canadian Forest Service
  
• Morgan, Mervyn G.
  Canadian Forest Service
  

Defoliation by spruce budworm (Choristoneura fumiferana [Clem.]) is a major constraint to management of spruce-fir forests in eastern North America. Spruce budworm outbreaks affected an estimated 57 million ha of forest in the 1970s (Blais 1983, Kettela 1983) and resulted in the loss of 44 million m3 yr-l of timber in Canada from 1977 to 1981 (Stemer and Davidson 1982). Outbreaks result in severe defoliation of balsam fr (Abies balsamea [L.] Mill.) and spruce (Picea qp.) foliage, which reduces volume and height growth, causes stem deformities, increases susceptibility to secondary insects and diseases, and generally results in tree mortality (Maclean 1985). Information on the impact of budworm outbreaks is needed by forest managers to predict forest yields accurately, to make effective use of timber for the production of pulp, paper and lumber, and to calculate sustainable harvest levels