SUSCEPTIBILITY OF NORWAY SPRUCE PLANTATIONS TO WHITE-PINE WEEVIL ATTACKS IN SOUTHERN QUEBEC

Annual levels of attack by the white pine weevil (Pissodes strobi Peck ) in 110 Norway spruce (Picea abies (L.) Karst.) plantations of southe rn Quebec were measured. The relationships between levels of attack an d site and stand characteristics were determined. In 1991, 84% of the plantations were affected by the weevil. Annual levels of aback increa sed from 2 to 25% of the trees between 1987 and 1991 for the 110 plant ations. Drainage and site quality index influenced the levels of attac k. On medium-textured soil ecosystems, plantations situated on imperfe ctly drained soils were significantly more affected (43%) than those o n well-drained soils (11%). Plantations located on the most productive sites (site quality index 13-14 m at 25 years) were less affected (8% ) than those on the least productive (7-8 m at 25 years) sites (34%). There was no significant correlation between plantation density and le vels of aback. The results showed that the white pine weevil is one of the most damaging pests of Norway spruce plantations in southern Queb ec. Norway spruce plantations should be monitored annually for damage detection. Appropriate sites should be selected for reforestation to m aximize productivity and minimize insect damage.