December, 1958 Carter: Applied Botany and Plant Pathology 



157 



from the Forest Preserve District of 

 Cook County, Illinois. A graduate stu- 

 dent at the University of Illinois, E. A. 

 Curl, was employed on a half-time basis. 

 A second grant of money was received 

 from the Forest Preserve District in 1951. 

 Also in 1951, funds were obtained from 

 the National Oak Wilt Research Com- 

 mittee of Memphis, Tennessee, composed 

 of 10 hardwood industries, and from state 

 appropriations for research on the dis- 

 eases of trees. These funds made it pos- 

 sible to add three plant pathologists in 

 1951 to conduct full-time research on the 

 oak wilt disease. The men employed were 

 Bert M. Zuckerman, George J. Stessel, 

 and Paul F. Hoffman. Additional funds 

 were obtained from the National Oak 

 Wilt Research Committee in 1952, 1953, 

 and 1954. Funds appropriated by the 

 state have continued to be a part of the 

 Natural History Survey's regular budget. 

 These funds have made it possible to em- 

 ploy additional plant pathologists to do 

 research on oak wilt and other tree dis- 

 eases. In 1953 four men full-time and 

 two men half-time were conducting re- 

 search on oak wilt. At present, with only 

 state funds to support the research on oak 

 wilt, three full-time regular staff mem- 

 bers are continuing research on this dis- 

 ease. The men who have helped to carry 

 on this program include E. A. Curl 

 (1950-1954), Bert M. Zuckerman, 

 George J. Stessel (1951-1952), Paul F. 

 Hoffman, Eugene B. Himelick (1952- 

 1954), Richard D. Schein (1952-1953), 

 Norman C. Schenck (1952-1953), Irving 

 R. Schneider, Harry Krueger (1954— 

 1955), Arthur W. Engelhard, Tames D. 

 Bilbruck (1955-1958), John M. Ferris, 

 R. Dan Neely, and Walter Hartstirn. 

 Persons whose names are followed by 

 dates were employed on research funds 

 granted to the Natural History Survey 

 by the Forest Preserve District of Cook 

 County, Illinois, or by the National Oak 

 Wilt Research Committee. The dates in- 

 dicate the periods of employment. Hime- 

 lick was employed on research funds 

 granted by the National Oak Wilt Re- 

 search Committee (1952-1954) before 

 he was employed by the Survey. 



As a result of this extensive research 

 program on oak wilt, many papers were 

 published. The phases of research covered 



in these papers include laboratory studies 

 on the morphology and physiology of the 

 fungus (Zuckerman & Curl 1953) and 

 isolation of the fungus from species of oak 

 on which it had not been previously re- 

 ported (Carter & Wysong 1951) ; green- 

 house studies on host range (Hoffman 

 1953) and experimental transmission of 

 the fungus by insects, mites, and squirrels 

 (Himelick, Curl, & Zuckerman 1954; 

 Himelick & Curl 1955, 1958) ; green- 

 house studies on infection by and spread 

 of C^*-labeled fungus in inoculated oaks 

 (Zuckerman & Hoffman 1953; Hoffman 

 & Zuckerman 1954) ; and field studies on 

 distribution and spread of oak wilt in 

 Illinois (Carter 1952), availability of oak 

 wilt inoculum in the state (Curl 1953, 

 1955rt, 1955^; Himelick, Schein, & Curl 

 1953), characteristic growth of the fungus 

 under natural conditions (Curl, Stessel, 

 & Zuckerman 1952), discovery of the 

 perfect stage of the fungus in nature 

 (Curl, Stessel, & Zuckerman 1953; 

 Stessel & Zuckerman 1953), and effect of 

 the fungus on oak fence posts (Walters, 

 Zuckerman, & Meek 1955). 



Other Diseases of Trees. — Al- 

 though oak wilt, elm phloem necrosis, 

 and Dutch elm disease are the most de- 

 structive tree diseases in the state, other 

 diseases of trees and of shrubs have been 

 sufficiently destructive to require the at- 

 tention of plant pathologists of the Nat- 

 ural History Survey. A wilt disease that 

 affects many species of trees in Illinois 

 is Verticillium wilt. It is known to affect 

 27 species of plants, including 7 varieties 

 of woody ornamentals representing 19 

 genera. Of the 27 species of woody hosts 

 of this disease, 12 were first reported in 

 Illinois: black locust, catalpa, Chinese, 

 English, and slippery elms, goldenrain 

 tree, linden, magnolia, multiflora rose, 

 tuDelo, wayfaring tree, and yellow-wood. 

 Maple, elm, and catalpa are frequently 

 affected by this disease. 



Canker diseases found in Illinois affect 

 different species of trees, including crab 

 apple, hawthorn, juniper, maple, moun- 

 tain ash, pine, poplar, redbud, spruce, 

 sycamore, and willow. Rust diseases are 

 widespread and destructive in some years. 

 They include cedar apple rust, cedar- 

 hawthorn rust, cedar-quince rust, pine 

 needle rust, and poplar leaf rust. 



