180 



Diseases of Economic Plants 



watermelon, gourd, and other cucurbits. The fungus winters 

 out of doors in the South and in the greenhouse in the North 

 and spreads thence to the fields annually if weather condi- 

 tions are favorable. 



This disease is often injurious to cucumbers under glass 



as well as in the field. 



It is well to sulfur 

 the greenhouses 

 thoroughly when not 

 in use and to clean 

 and whitewash all 

 walls and wood in 

 order to kill any fungi 

 present. Should the 

 disease appear, spray 

 at once as in field 

 pi-actice. For direc- 

 tion for field spraying 

 sec cucurbit spray- 

 ing, p. 191. 



Anthracnose -^-* -^'^' 

 ^^- {Colletotrichum la- 

 genm'ium (Pers.) E. 

 & H.). — This disease 

 was first noted in 

 1867 in Italy, and 

 is now common in 

 Europe and the 

 United States, occur- 

 ring on cucumber, 

 muskmelon, water- 

 melon, gourd, and a 

 few other related plants. The loss is severe on the three crops 

 first named, and is of more importance to cold-frame crops 

 and crops under glass than to field crops, though it some- 

 times does cause almost total loss of the latter. Upon the 

 leaf, circular, not angular, spots occur which, instead of 



Fig. 98. — Portion of watermelon showing 

 effect of anthracnose. After Sheldon. 



