DISEASES OF CULTIVATED PLANTS 587 



threshing machine and all other sorts of machinery and implements, 

 bins, sacks, etc., that the smutty grain touches. As a consequence 

 of this, clean wheat passed through any such channels, through 

 which smutty wheat has just passed, takes up the spores, and if used 

 for seed without treatment the resulting crop will be almost certain 

 to have smut in it. 



From the very great abundance of spores set free by the broken 

 smut balls, there is much greater danger of spreading this disease, 

 as above suggested, than in the case with oats. This smut of wheat 

 is scarcely at all distributed by the wind but depends upon the above 

 mentioned means for distribution. Such means are so effective that 

 if the disease is introduced and permitted to run its own course, 

 only a few years would be required before it would practically de- 

 stroy the entire crop. 



Preventive Treatment. It is highly advisable, whenever pos- 

 sible, not to use wheat for seed that is Known to contain stinking 

 smut. If wheat known to be clean is not procurable, the smutty 

 wheat should first be thoroughly cleaned with a good fanning mill, 

 using a blast strong enough to blow out the unbroken smut balls 

 even if the lighter sound kernels are blown over also. The spores 

 that are attached to the sound kernels can then be killed without 

 hurting the wheat 'by treating the grain with a formalin solution 

 in the same way as prescribed for oats. To prevent reinoculation 

 with smut after such treatment, the same methods should be used 

 as with oats. 



Stinking smut can be eradicated in at least two years by care- 

 fully treating the seed wheat and always guarding against all pos- 

 sible sources of reinoculation. The threshing machine is really one 

 of the most important sources to watch, and the greater the co-opera- 

 tion between neighbors using the same machine the better. If this 

 or some other source of possible inoculation can not always be en- 

 tirely avoided, it is advisable to clean the grain well and apply the 

 formalin treatment carefully and thoroughly before using for seed. 



Treatment With Copper Sulphate or Bluestone Solution. This 

 method was first used in Europe over one hundred years ago for 

 seed treatment to prevent smut. It is especially applicable for stink- 

 ing smut of wheat. As shown by this department, it tends to in- 

 jure, somewhat, the germination and early growth of oats. 



In general there are two methods of applying this treatment: 

 either soaking the seed in a strong solution for a short time or soak- 

 ing the seed in a weak solution for a long time. Either method is 

 effective. The former has been more generally used because the 

 seed does not become so water-soaked. This treatment consists in 

 soaking the seed grain for five minutes in a solution of one pound 

 of copper sulphate to each gallon of water. The treatment with the 

 weaker solution requires the soaking of the seed grain for about 12 

 hours in a solution of one pound of copper sulphate to each 25 gal- 

 lons of water. Any gradations of time and strength of .solution be- 

 tween these extremes might be used; the object always being to 

 kill the smut spores without endangering the vitality of the grain. 



