OAT SMUT 



203 



heads mature before the healthy ones, and as the straw of 

 the diseased plants is usually shorter, the smutted heads are 

 not readily seen at harvest time and the actual damage from 

 the disease is usually underestimated. It probably averages 

 2 or 3 per cent of the crop, or from $6,000,000 to $10,000,000 

 annually for the United 

 States. In some fields 

 it may destroy as much 

 as half the crop. For- 

 tunately, both kinds of 

 oat smut are easily and 

 cheaply controlled by 

 the use of the formalde- 

 hyde solution (Sec. 205). 

 This treatment is so 

 cheap and so entirely 

 effective that farmers 

 can not afford to neg- 

 lect it. Seed should be 

 treated at least as often 

 as every alternate year, 

 and treatment every 

 year is much safer. 

 Even though all the 

 smut on a given farm 

 may be destroyed, it is 

 pretty certain that some 

 of the spores will be 

 scattered through the 

 thrashed grain, having been carried from neighboring 

 farms in the thrashing machine, so that treatment every 

 year is the surest way of keeping down this disease. 



Fig. 70. Oat smut; normal head at the left, 

 smutted head on the right. 



