302 



Diseases of Economic Plants 



The grains, usually only 

 larged, spherical, 5 mm. 



few in each head, become en- 

 more thick, and coated with 

 a dark green powder. Some- 

 times a yellow color prevails 

 instead of the green. In sec- 

 tion the interior is seen to be 

 filled with a compact white 

 mass bordered by a brownish 

 yellow zone, then by the green 

 coating. 



Though the disease has been 

 known in Louisiana for ten or 



Fig. 159. — -Rice showing 

 " green-smut." After Fulton. 



more years, and is present to 

 some extent in most fields, it is 

 not considered serious, since 

 rarely more than 0.25 per cent 

 of the heads, and only a few 

 grains per head, are affected. 



Black-smut ^^" (Tilletia horrida 

 Tak.). — A dark, unsalable flour, 

 made from rice in the region of 

 Georgetown, S. C, was reported 

 in 1898. Anderson found that 

 many heads of rice from these 

 fields bore as much as 25 per 

 cent of smutted grains. 



This smut was probably imported from Japan in infected 

 seed, but due to the immediate action of Anderson and 

 Walker the pest seems to have been completely stamped 



Fig. 160. — Rice showing 

 black-smut. After Fulton. 



