614 INSECTS AFFECTING VEGETATION 



seed should be frequently stirred in order to keep the temperature 

 uniform throughout. Small sacks should be used, since in large 

 sacks it is impossible to keep the temperature constant. After this 

 treatment the seed is spread out to dry on a clean floor or canvas. 

 When sufficiently dry it may be sown. 



As in the formalin treatment, every precaution must be taken 

 to prevent infection of the seed after treatment. Although this 

 treatment is not as convenient as the formalin method, it is just as 

 efficient, is cheaper, and, on account of the wide range of tempera- 

 ture, is easily applied. It is superior to the formalin method in that 

 the farmer does not have to rely on a druggist for the strength of a 

 formalin solution. If the formalin is not of full standard strength 

 (i. e., a 40 per cent, solution), the formalin treatment may not be 

 successful. In the hot-water treatment all of the implements and 

 materials are directly under the control of the farmer. 



Copper Sulphate Treatment. Solutions of copper sulphate 

 (bluestone) also give satisfactory results, but are certainly no better 

 than, and probably not even as good as, the two methods described 

 above. 



Head Smut. At present the head smut does not occur in 

 abundance beyond a very restricted area in the Panhandle of Texas. 

 Its life history is not yet understood, but enough is known to show 

 that the treatments recommended for the grain smut have abso- 

 lutely no effect upon the head smut. This indicates that this dis- 

 ease may be more difficult to control than the grain smut when once 

 it succeeds in getting a fair start. 



The only recommendation that can be made at the present time 

 is to keep the smut away from the farm and the community. In 

 order to do this the farmer must be sure that his seed did riot come 

 from a crop that contained head smut. If it is allowed to spread un- 

 checked, it bids fair to become troublesome in the future. In case 

 it is already present on the farm the infected plants should be cut 

 out completely and burned before the smut spores have a chance to 

 scatter. 



Recommendations. The precautions necessary and the proper 

 treatments for the smuts of sorghum crops may be summarized as 

 follows : 



(1) If possible, get seed free from smut from fields that are 

 known to have had no smut during the preceding year. Also be 

 sure that such seed has not become smutted in harvesting and 

 handling. 



(2) Keep your farm free from smut by using your own seed 

 and employing only machinery that will not contaminate your crop. 

 These first two precautions will insure you against both kinds of 

 smut. 



(3) Treat your seed with either formalin or hot water if you 

 are not sure that it is free from smut. This will not necessarily 

 insure the farm against head smut. 



(4) Maintain a quarantine against any locality or farm w r here 

 smut is known to exist, as well as against any seed grower who allows 



