612 INSECTS 'AFFECTING VEGETATION 



of diseased flax straw and chaff which would not be sufficiently 

 treated to kill the fungus inside of them. 



14. After treating, it may be well to sow two or three quarts 

 more per acre, as some of the weaker seeds are apt to be killed. 



15. Scaly flax seed and seed which has been wet is always 

 very poor for seed. Such seeds harbor the spores of fungi which 

 kill the young plants as soon as the seeds germinate. 



16. Cease sowing flax year after year upon the same land. 

 Put at least one cultivated crop and two or more other crops between 

 flax crops. 



17. Burn as much of the old flax straw and stubble which 

 remains upon the ground as possible. 



18. Raise your own flax seed, grade it up to the best. Watch 

 for diseased areas and notify the station. Thresh your seed, when 

 you can, in your own machine from a patch of strong healthy flax 

 and store it in a clean bin. 



19. Keep all the flax straw out of the barnyard, unless it is 

 intended to put all manures through a several years composting 

 process. (N. Dak. E. S. B. 50.) 



SMUTS OF SORGHUM. 



Kinds of Sorghum Smuts. There are in this country two well- 

 known smuts of sorghums: The grain, or kernel, smut (Sphace- 

 lotheca sorghi) and the head smut (Sphacelotheca reiliana). The 

 grain, or kernel, smut is easily distinguished by the fact that only 

 the individual kernels, or grains, are affected, while the head re- 

 tains its usual form and nearly its usual appearance. Most, if not 

 all, of the kernels in a smutted head are usually destroyed. Each 

 kernel is changed into a more or less conical, grayish to reddish mass 

 containing the dark-colored smut dust, or spores. 



The head smut is very different in appearance. The whole 

 head, just as it emerges from the upper leaf, is converted into a 

 single large smut mass, covered by a whitish or grayish membrane, 

 which soon bursts and sets the spores free. In this smut, therefore, 

 all trace of the individual grains, or kernels, is lost. The smut mass 

 resembles somewhat in appearance a smut mass on corn. 



It is not yet known how many of the various groups and varie- 

 ties of sorghum each smut infects. The grain smut occurs on all 

 .of the principal groups, while the head smut has been observed on 

 Borgos (sweet sorghums), kafirs, and shallu. Neither smut has been 

 observed on milo up to the present time, and attempts to inoculate 

 milo with the kernel smut of kafirs and sorgos have proved un- 

 successful. 



Grain, or Kernel, Smut. Of the two smuts of sorghum, the 

 kernel smut is at present the more widely distributed. It is found 

 almost universally where sorghum crops are grown. The losses sus- 

 tained are in many districts very severe. They are increasing and 

 will continue to increase unless preventive measures are adopted. 



The life history of this grain smut is now well known. It is 

 similar to that of stinking smut, or bunt, of wheat, viz, the spores, 

 or smut dust, get on the kernels in threshing or in handling, and 



