So far this year the Plant Clinic has confirmed oak wilt in St. Clair and Stephenson counties. In 2004 the clinic isolated the fungus, confirming oak wilt in DuPage, Henry, JoDaviess, Lee, Madison, Marshall, Mason, Stephenson, Tazewell, and Winnebago counties. This information is reflective only of Plant Clinic samples; I do not mean to imply that oak wilt is not in other counties. For example, it has been found in Champaign County but has not been confirmed at the Plant Clinic since 2000. This information still has great value. If you live in one of these counties, know that recently confirmed cases of oak wilt have occurred in your area. Do not prune oaks during the growing season in those areas if possible. Most of the oak wilt literature says not to prune until mid-July. If you can wait until fall to avoid attracting beetles that might carry the oak wilt fungus spores, that would be a safer plan of attack.