374 



1 I XGOUS DISEASES OF PLANTS 



Control. In an endeavor to control smut in oats, bunt in wheat, 

 and other more or less similar diseases, a careful study has been 

 made of a variety of fungicides or toxic agents in solution, and of 

 hot water. 



The hot water treatment of the seed grain is the method in 

 more common use. This method consists in immersing for ten 

 minutes in water at a temperature of from 132 to 133 F. It has 

 been found desirable to put the seeds into a basket or perforated 

 tin vessel, and this may be previously dipped into warm water at a 

 temperature of about 110 to 120 F., in order that the tempera- 

 ture of the hot water may not be greatly reduced by using cold 

 seed. The water in which the seeds are finally immersed should 



be retained during 

 the ten minutes at 

 a temperature of 

 not less than 130, 

 otherwise additional 

 warm water should 

 be added during the 

 process. Further- 

 more, it is desirable 

 to throw the seed 

 into cold water be- 

 fore treatment, so 

 that the smutted 

 seed may be floated and skimmed off, for the treatment would be 

 of small value if the large quantity of spores still held within the 

 kernels of smutted grain were not removed. The hot water method 

 is effective, but since it appears somewhat complicated, it is now 

 bc-ing superseded by a formalin treatment. In its simplest terms 

 the latter consists in dipping the seed in a solution containing 

 i pint of formalin to 30 gallons of water. The seed may be put 

 into surks or baskets of from ^ to i bushel each, and, as before, 

 immersed in the barrel of formalin solution for about ten minutes, 

 drained, put away wet in the saeks, or heaped and covered for two 

 hours and finally spread out to dry rapidly before danger of germi- 

 nation. Shoveling over will facilitate the drying. Copper sulfate, 

 potassium sulfide, and other germicides have also been employed. 



FIG. 190. USTILAGO AVENGE: GKRMINATING SPORES 



