CHAPTER IV 
DISEASES DUE TO FUNGI—Continued 
2. Wilt Diseases 
“ SLEEPY DisEAsE”’ or wilt disease is common to most 
plants, and is indicated by a wilting of the leaves followed 
by a yellowing and desiccation which usually ends in the 
death of the individual. Obviously any root injury, if 
sufficiently drastic, will cause such symptoms, but the 
true wilt diseases are due to a reduced functioning or 
complete stoppage of the vascular system, which com- 
prises the water- and food-conducting tissues of the plant. 
Massee (31) first described the Sleepy Disease of 
tomatoes in Britain and attributed it to Fusarium 
lycopersict Sacc., an organism with two developmental 
- stages—the Diplocladium and Fusarium stages. In- 
vestigations at the Cheshunt Experimental Station (10) 
demonstrated that these two stages are separate fungus 
species, each of which under definite conditions can 
produce wilt. The Diplocladium form is Verticilliwm 
albo-atrum Reinke and Berthold, and the pathogenic 
Fusarium form is Fusarium lycopersici Sacc. There are 
therefore two wilt diseases of the tomato in Britain— 
the Verticillium wilt and the Fusariwm wilt—and other 
workers have shown that many other cultivated plants 
are susceptible to these two wilt diseases. 
VERTICILLIUM WILT OF THE TOMATO 
Verticillium wilt is widely distributed throughout the 
_ British and Channel Islands where tomatoes are grown, 
73 
