WHITE SPRUCE RESISTANCE TO WHITE-PINE WEEVIL RELATED TO BARK RESIN CANAL DENSITY

Examination of the bark from the uppermost lateral branches of white s pruce, Picea glauca (Moench) Voss, indicated that trees resistant to a ttack by the white pine weevil, Pissodes strobi Peck, had significantl y higher number and density of vertical resin canals per unit of bark area (mm(2)) than susceptible toes. The number and density of resin ca nals were also positively correlated with tree growth rate, an indicat or of tree vigor. The density of the resin canals found near the perip hery of the bark (outer resin canals) had higher correlation with resi stance and growth than inner resin canals. Measurements of resin canal s on the bark of lateral branches correlated well with measurements on the bark of the leader of the same tree, indicating that lateral samp les could be used to screen white spruce for resistance to weevils.