I reported the presence of the disease to Mr. Wilkinson and to Dr. Colby and they were surprised to see the disease on Busseron in any location, and particularly that far north.
In the south this disease frequently affects Schley, Delmas, Alley and Van Deman and some others. Formerly the trees were sprayed with Bordeaux Mixture. I think they are using Zerlate now. It's a problem to be reckoned with. It occurs on the nuts and on the leaves, and it is carried over winter on the stems and the one-year shoots.
Further News About Oak Wilt
E. A. CURL, Illinois Natural History Survey, Urbana, Ill.
In 1951 a review of the oak wilt situation was given in a paper, "Present Status of the Oak Wilt Disease", at the Forty-Second Annual Meeting of the N.N.G.A. at the University of Illinois. The following report is aimed at bringing up to date the present known distribution of the oak wilt disease, recent developments in scientific research on the disease, and possible control measures.
The oak wilt disease is caused by the fungus Chalara quercina Henry and is characterized by a very noticeable bronzing and wilting of leaves that drop prematurely. Brown streaks are usually present in the outer sapwood. These symptoms may be seen from June to September or until normal autumn colors of the foliage develop.
More than 30 species of oak are known to be susceptible to the disease. Other susceptible genera of the family Fagaceae are Chinese chestnut, Castanea mollissima, golden chinquapin, Castanopsis chrysophylla, tanbark oak, Lithocarpus densifiora, and Nothofagus from South America. The red and black oaks seem to be most susceptible and are often killed within 6 weeks after infection.
Distribution
During the past few years the oak wilt disease has spread with such rapidity and destructiveness among valuable forest and shade oaks in parts of the eastern half of the United States that its seriousness is now well recognized. At present oak wilt is known to be in the following states: Wisconsin, Iowa, Minnesota, Illinois, Missouri, Indiana, northern Arkansas, eastern Kansas, southeastern Nebraska, Ohio, Pennsylvania, West Virginia, northwestern Virginia, western part of North Carolina, eastern Tennessee, northeastern Kentucky, western Maryland and southern Michigan. Aerial surveys for 1952 are not yet complete, but there are indications of extensive new infections in Pennsylvania, Ohio, and West Virginia while the other states show a moderate increase in the number of infections.
The first case of oak wilt in Illinois was seen in Rockford in 1942. Today 54 of the 102 counties in the state have oak wilt areas. The disease is present in both the extreme northern part and the southern-most tip of the state. Practically all wilt areas in the southern half of Illinois consist of 5 trees or less that appear to have died within the last 4 years, indicating a recent spread of the disease southward. A similar condition exists in southern Missouri and northern Arkansas.