CEPHALOSPORIUM ELM WILT IN MASSACHUSETTS 



By Malcolm A. McKenzie, Assistant Research Professor of Botany, and 

 Eunice M. Johnson, Institutional Fellow, Department of Botany i 



INTRODUCTION 



The widespread occurrence, in Massachusetts, of a wih disease of American 

 elm ( Ulmiis americana I^.) associated with a fungus belonging to the genus 



Cephalosporium as described by 

 Corda, became apparent during 

 recent surveys of the State for 

 shade tree pests. Figure 1 shows 

 an elm in which the disease had 

 leached a rather advanced stage 

 by midsummer. Infections by 

 the causal fungus which Occur 

 eaily in the growing season are 

 \ frequently particularly destruc- 



tive. Because of the limited 

 extant knowledge concerning 

 the wilt in elm, it was consid- 

 ered advisable to make further 

 investigations of this diocase. 

 Accordingly, studies have been 

 made of the course of the disease 

 in different species and varieties 

 of elm, the relation of the fungus 

 pathogen to the host (including 

 the possible means of fungus 

 entrance, fungus development 

 in the host tissues, and host 

 reaction), and the morphology, 

 physiology, and life-history of 

 the organism. The present 

 report describes the results of 

 these investigations in compaii- 

 son with previously published 

 reports by various investigators. 

 The American elm is the most 

 wideh' planted shade tree in New 

 England. It has been used in 

 street iJJanting since early colo- 

 nial days and the majority of 

 our old Alassachusetls towns have grown up around elm-shaded commons. 

 The elm is as much a i)art of the tradition of Massachusetts, and of all New 



Fij4ure 1 . An American Elm in midsummer, 

 from which the fundus, Cephalosporium sp.. was 

 isolated in cultural studies. 



Photo}>raph by Irving D. Hardy. 



^The writers are indebted to Prof. \. Vincent Osmun, Head of Department of Botany, for his 

 advice and sustained interest din inK tlie course of tlie investigations reported in this publication. 



