Three major fungi cause wilt and death to trees in Illinois. The diseases of concern are Dutch elm disease, oak wilt, and Verticillium wilt. Refer to issues no. 5 and 13 (2007) to read about Verticillium wilt. Oak wilt is discussed in issues no. 7 and 11.
The following summaries of Plant Clinic fungal wilts for 2007 may be of value to many. There are still cultures incubating, so numbers are not final for the year; but this information may alert some of you to the presence of these diseases in your area.
Oak wilt positives are based on isolations of the causal fungus.
As of September 21, the U of I Plant Clinic has confirmed oak wilt in the following counties in 2007: Champaign (3), DuPage (1), Ford (1), Menard (1), Monroe (1), Ogle (1), Sangamon (1), and Warren (1).
Although most American elms were killed by Dutch elm disease (DED) nearly five decades ago, each year we still isolate the causal fungus from elms through laboratory culturing at the U of I Plant Clinic.
In 2007, positive cases of DED, based on isolation of the pathogen, were detected in the following counties: Boone (1), Cook (7), DuPage (1), and Kane (2).
Verticillium wilt is more widespread than oak wilt or Dutch elm disease, in both geography and host range.
Based on positive isolations of the Verticillium fungus, Plant Clinic staff found positive cases of Verticillium wilt in the following counties in 2007: Champaign, Cook, DuPage, Hancock, Lake, and Lee. Most involved maples species. Magnolia, fragrant sumac, and redbud were also infected.
This information is not intended to show trends. It is not survey information but merely a record of information on unsolicited plant samples.