20 



Diseases of Economic Plants 



of fungi, prominent among them being Pythium, Thielavia, 

 Corticium, Fusarium, Botiytis, Sclerotinia, Sclerotium, 

 Phoma, Volutella, Phytophthora, Colletotrichuin, Gloeospo- 



FiG. 4. — Stems of young greenhouse tomato plants damped- 

 off frcm attacks of Corticium. After Humbert. 



rium. The fungus which causes this condition maj^ often be 

 seen as a weft of mycehum around the base of the diseased 

 plant, or even creeping over the ground to some distance. 



