Negligible Cull and Growth Loss of Jack Pine Associated with Globose Gall Rust

Abstract

The height and diameter of galled and unaffected jack pine (Pinus banksiana Lamb.) were compared for five stands in northwestern Ontario. The severity of infection by globose gall rust (Endocronartium harknessii [J.P. Moore] Y. Hirat.) was rated as the total number of galls per tree and the number of stem galls per tree.Comparison of galled with unaffected trees in all stands showed essentially no size difference. Tree size increased relative to the number of galls per tree in one of the stands. This relationship was interpreted as reflecting that large individuals had more sites susceptible to infection. Trees were more uniform in size for the other stands and no size difference associated with numbers of galls was apparent.Galls were observed on the branches but not on the main stem of trees studied in mature stands. Hence, defect associated with the merchantable portion of the bole was nil. Both stem galls and branch galls were fairly common in young stands, an indication that jack pines with stem galls usually die as stands mature. Observations in other jack pine stands indicate that galled tissue and associated tree parts frequently do die.