DISEASES OF CEREALS AND GRASSES 43 



with ^ per cent solution of copper sulphate (see 

 page 29) or with formaldehyde solution (p. 32). 



(c) Wheat Smut { Ustilago Tritici)^ 



This is sometimes called loose smut, and must 

 not be confused with bunt (stinking smut) (see p. 45). 

 The mycelium uses up not only the nutriment in- 

 tended for the development of the grain, but the 

 chaff is also attacked. 



Prevention. — Difficult to combat, as copper or 

 formaldehyde solutions are apparently 

 ineffective. It can, however, be com- 

 pletely controlled by the use of the 

 modified hot water treatment (p. 30). 

 Inasmuch as this is a slow process — 

 not more than 8-10 bushels of grain 

 can be treated in a day, — it is sug- 

 ofested that sufficient grrain be treated 

 each year to plant a plot of two or 

 three acres from which the seed for 

 next year's sowing may be obtained. 

 This seed plot should be planted away 

 from other fields of wheat so as to 

 avoid infection of the seed at blossom- 

 ing time by the spores carried by the 

 wind from such other fields. 



(d) Rye Snint ( Urocystis occultci). 



This is seen in the form of grey stripes, mostly 

 on the stem but also on the leaves, which latter 

 burst and expose the black spores (Fig. 10). 



Img. 10. — A ball 

 of spores of 

 Urocystis oc- 

 cnl t a ( r >■ e 

 smut). In the 

 centre the dark 

 fertile spores, 

 one of which 

 has sent out a 

 short pro-my- 

 celium (/>) ; 

 these are sur- 

 rounded by 

 sterile spores 

 (s). (Highly 

 maojnified.) 



