344 



DISEASES OF ECONOMIC PLANTS 



Usually all the spike- 

 lets of a head and all 

 the heads of the 

 affected plant are 

 smutted. There is 

 considerable difference 

 in the resistance of- 

 fered by different va- 

 rieties, but in view of 

 the perfect protection 

 afforded by proper 

 treatment this is of 

 little significance. 



The damage caused 

 by smut is usually 

 underrated. In 1884 

 Arthur^ in New York 

 by actual count found 

 the oat smut to con- 

 stitute from 8.5 to 10 

 per cent of the ordi- 

 nary crop. By actual 

 count of nearly 1 1 ,000 

 heads Plumb = in 1886 

 determined the amount 

 of smut to be 8.4 per 

 cent ; in some fields he found as high as 20, 28, and even 30 

 per cent. Kellerman and Swingle,^ counting smutted heads 



> Arthur, J. C, N.Y. (Geneva) Agr. Exp. Sta. Rpt. 3, p. 382, 1884. 

 => Plumb, C. S., N.Y. (Geneva) Agr. E.-ip. Sta. Rpt. 5. 

 3 Kellerman, W. A., and Swingle, W. T., Kans. Agr. Exp. Sta. Rpt., 

 p. 213, 1889. 



Fig. 147. — Smut (Ustitago avencs) on oats. 

 After JacksoD. 



