354 



DISEASES OF ECONOMIC. PLANTS 



crop unworthy of harvesting. Plants attacked later jneld 

 some grains which are of poor, light quality, easily broken 

 or blown away, and consequently largely lost in milling and 

 threshing. The variation in size of the grain also largely 

 depreciates the quality. Many of the heads, especially 

 the heavier ones, fall off, and some fields show at least one 



third of the crop thus left 

 upon the. ground. 



The Rice Committee of 

 the Agricultural Society in 

 South Carolina, March, 1904, 

 estimated the loss, up to 

 that time, to be very nearly 

 $1,000,000. Depreciation in 

 land values, necessitating 

 abandonment of land, is a 

 not insignificant item of 

 charge against this disease. 



While the disease can be 

 stopped by spraying with 

 5-5-50 Bordeaux mixture, 

 this course is not practicable 

 with such a crop as rice. The chief hope hes in the use 

 of resistant varieties. Withholding nitrogenous fertilizers 

 and removal of infective trash by burning are good sani- 

 tary measures. 



Green smut (Ustilaginoidea virens (Cke.) Tak.). — This 

 grain disease, though partaking of the appearance of a 

 true smut, is in reality more closely related to the ergot of 

 rye. The grains, usually only a few in each head, become 

 enlarged, spherical, 5 mm. or more thick, and coated 



Fio. 151. 



-Rice showing " green smut.' 

 After Fulton. 



