Greetings Jerry:
Thank you for your question and might I make the following suggestions. Universities, state agencies, and federal agencies always provide reliable forestry information. With that said, might I offer the following options:
Illinois Extension Forestry: http://web.extension.uiuc.edu/forestry/home.html
University of Wisconsin Extension Forestry: http://forest.wisc.edu/extension/
Wisconsin Department of Natural Resources - Division of Forestry: http://dnr.wi.gov/Forestry/
And of course, always feel free to contact a local DNR state forester or a local professional consulting forester for on-site assistance.
Best of luck!