Download or read book Hazard Rating System for Spruce Weevil (Pissodes Strobi) in Sitka Spruce in the Northern Oregon Coast Range written by Teresa Lysak and published by . This book was released on 2000 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: The spruce weevil (Pissodes strobi) is a serious pest of Sitka spruce in Oregon. Weevils cause damage by killing the leader of a tree, resulting in defects such as crooks and forks that can render the tree unmerchantable. In this study, spruce stands 16-25 years old were surveyed for weevil damage. Trees had an average of 2.8 defects, ranging from 0 to 10, with minor crooks being the most common type of defect. More defects were seen in the upper portions of the trees than in the lower portions. Only 7% of the stands contained more than 200 undamaged trees per acre. The amount of damage was found to be positively correlated with distance from the ocean and growth rate and negatively correlated with elevation, latitude, and amount of spruce in the stand. These variables together explained 62% of the variation in amount of damage.