Limiting White Pine Weevil Attacks by Side Shade

Abstract

An experiment to limit damage by the white pine weevil (Pissodes strobi Peck), using strip-cuts aligned north-south to control the number of hours of direct sunlight falling on seedlings of white pine (Pinus strobus L.) planted on the strips, was carried out from 1964 to 1982 at the Petawawa National Forestry Institute. Strip widths (in relation to stand height) that would admit nominal values of 25, 50, 75, and 100% of daily full light were employed, and the experiment conducted in a pine-mixedwood and a mixed hardwood stand. Percentages of trees attacked by the weevil were clearly stratified by treatment in the mixed-wood stand, increasing from the narrow (25% light) to the open (100% light) strips. It was concluded that clear-cut strips in conifers or mixedwoods, where the ratio of strip width to stand height is in the range of 0.66 to 1.00 (admitting a nominal 50 to 75% of full light), will allow adequate numbers of white pine to reach a height of one log-length (5.2 m) free from weevil damage. However, rate of height growth will be diminished. This approach, which holds promise for natural regeneration of the pine or stand conversion by planting, is not effective in hardwood stands because leafless trees will not provide the necessary side shade when adult weevils are active in early spring.