. Bulletin. Natural history; Natural history. 156 Natlrai. History Survi-v Vol. 27. Art. 2. Plant pathologists of the Illinois Natural History Survey culturing sample of American elm suspected of being affected by the Dutch elm disease. Modern laboratory equipment enables the plant pathologists to substantiate field diagnoses. Urbana in 1951. The numbers of affected trees in succeeding years in Champaign and Urbana were 11 in 1952, 164 in 1953, 694 in 1954, 1,805 in 1955, 1,836 in 1956, and 2,116 in 1957. These 6,627 diseased elms represent over 44 per cent of the elm pop
. Bulletin. Natural history; Natural history. 156 Natlrai. History Survi-v Vol. 27. Art. 2. Plant pathologists of the Illinois Natural History Survey culturing sample of American elm suspected of being affected by the Dutch elm disease. Modern laboratory equipment enables the plant pathologists to substantiate field diagnoses. Urbana in 1951. The numbers of affected trees in succeeding years in Champaign and Urbana were 11 in 1952, 164 in 1953, 694 in 1954, 1,805 in 1955, 1,836 in 1956, and 2,116 in 1957. These 6,627 diseased elms represent over 44 per cent of the elm population of Champaign and Urbana when the disease was first found there. The Natural History Survey has had one full-time plant pathologist conducting research on elm diseases, including Dutch elm disease, since July, 1951 : Ralph W. Ames in 1951 and 1952 and Richard J. Campana in 1952 and later. Oak Diseases.—Numerous inquiries about diseases of oak during the 1930's led to a special investigation which culmi- nated in the publishing of a preliminary report (Carter 1941). Although a dozen fungi were associated with the develop- ment of canker and dieback diseases of oak in the field, only one fungus, Dothio- rella quercina, caused canker and die- back under controlled experimental con- ditions. The other organisms appeared to produce canker and dieback only on trees previously weakened by adverse growing conditions. Oak wilt, the most destructive and widespread disease of oak trees in the United States, was not found in Illinois until 1942, when a few affected trees were discovered in IngersoU Park at Rockford in Winnebago County. In fol- lowing years the disease was found in other counties; by 1958 it was killing trees in 70 of the 102 counties of the state. Extensive research on the disease was started in 1950 with a grant of money. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and app
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