Itasca Park: Old growth and bark beetles / Three years after the big blow
Formal projects conducted by researchers from Syracuse and Dartmouth Universities continue in Itasca State Park to track bark beetle populations, associated insects and their potential impact on old growth pine. These projects and associated trap catches for 1998 indicate beetle populations may be back to endemic levels common before the windstorms of 1995 & 1996. Draft reports are expected this winter. The Park is demobilizing its massive trapping project and is returning traps to their original owners or making them available for project work upon request to the Regional Health Specialists.
Four less formal studies tracked by Forest Health Specialists, indicate the bark beetles were never able to fully utilize the large log materials dropped by the wind storms. Wet summer weather in 1995 and 1996 kept standing trees in an unstressed condition. In salvaged and unsalvaged areas no additional mortality to standing red and white pines could be attributed directly to bark beetles. Only mature jack pine on the study areas seemed to have been killed by beetles. Prescribed fire, however, did kill additional standing pine of all species; but within the losses deemed acceptable in the burn plan. While traditional bark beetle "pocket kill" continued on red pine in the Indian Mounds area and in overage jack pine stands, it was not observed in the diverse older pine stands that included more pine age classes, other hardwood and conifer species, and more shading of the ground surface. Hopefully, these general observations and specific research results can help us risk rate blow down events and tailor salvage and trapping programs to specific stands and locations in proximity to these point events. We'll keep you posted!
|Late season anthracnose
rips bur oak across southern Minnesota
By mid-August many scattered bur oaks across southern Minnesota experienced an outbreak of late season oak anthracnose. The severity of symptoms varied but were generally quite heavy. Infected foliage turned brown on much of the lower two thirds of the crowns. In years when this leaf disease occurs there is always much variability from tree to tree. It's common to see one or two affected trees adjacent to twenty or more unaffected trees. Thank goodness for genetic variability! Many of these bur oaks will experience this disease each year to some extent. There is no long term impact from late season outbreaks of anthracnose, so treatment is not recommended.
There was a lot of concern that this might be oak wilt disease. Oak wilt in bur oak would look much different as individual branches would dieback from the top down or from the outer crown inward.