Distribution of butternut canker - 1999. Conifer Pests Mortality of plantation-grown red pine seedlings was reported from northeast, western and central Wisconsin in 1998 and 1999. Seedlings planted within the last 8 years showed symptoms of top dieback, branch mortality and whole tree mortality. A survey of the most severely affected sites was conducted during 1999 and the pathogen, Sphaeropsis sapinea, was observed causing collar rot. S. sapinea is widespread in Wisconsin and causes mortality of elongating shoots and whole branches of red pine.
Collar rot or infection of the root collar area is a relatively new disease phenomenon.
A relationship between drought stress and accelerated growth of S. sapinea has been proven through research and is likely a key to the recent mortality. Results of the 1999 survey will be summarized in the WI DNR Forest Health Protection Annual Report, 1999. Populations of jack pine budworm declined dramatically in Washburn, Douglas, and Bayfield Counties but rose in Polk county where moderate defoliation occurred on 250 acres. Defoliation was light in Adams and Juneau Counties although high egg counts here may cause defoliation again in 2000. In April and May of 1999, chlorosis and casting of 1998 needles occurred on white pine throughout Wisconsin.