BUREAU OF PLANT INDUSTRY. 135 



doing immense damage, once it is generally disseminated. How long 

 it has been in the country and when and where first introduced are 

 not known. It has attracted considerable attention in Kansas since 

 1915 and must have been in that State much earlier than 1915. It is 

 quite certain that it has been disseminated from Kansas to other 

 States on seed wheat several times in recent years, both north and 

 south. It is a disease admii-ahly adapted to general dissemination, 

 owing to the fact that the organism after attacking leaves, stems, and 

 heads of the wheat finally lodges on and in the kernels, by way of 

 which it is carried over to the crop of the following season. The 

 kernels of badly attacked heads are shriveled, and such kernels are 

 very likely to be carriers of the organism either on their surface or 

 in their interior. Bacterial cavities in the interior of such wheat 

 grains are very common. The more conspicuous signs of the disease 

 are brown stripes on leaves, or many whole leaves dead in advance of 

 maturity; black stripes on stems, especially the upper parts and 

 often on all sides, so that the stem is nearly girdled in advance of 

 the ripening of the grain; a dark stain on the joints of the rachis; 

 and parallel black lines or stripes on the glumes. The awns are 

 also often black in whole or in part. Frequently there is a yellow 

 bacterial ooze from leaves, stems, and heads, in the latter case both 

 to the surface and inward over the grains. 



It is of the utmost importance to know speedily the extent to 

 which this disease has gained a foothold in the United States and 

 to restrict its spread in every possible way. 



Further observations and experiments are under way in coopera- 

 tion with the experiment stations of Wisconsin and Kansas, but 

 enough has been learned to make it certain that the disease is trans- 

 mitted on the seed. Plump kernels do not contain bacterial cavities, 

 but shriveled ones often do. At the very least, therefore, the latter 

 should be screened out carefully from all wheat designed for seed. 

 Farmers whose fields are now free from this disease should be on 

 their guard against its introduction, since if once introduced it is 

 likely to remain in the soil indefinitely. 



SMUT or CEREALS. 



The studies of bunt or stinking smut which were begun recently 

 in cooperation with the State Agricultural Experiment Station at 

 Pullman, Wash., have yielded some important results. They have 

 shown that the solution of the bunt problem in the Pacific North- 

 west depends, at least largely, upon (1) the general practice of crop 

 rotation, (2) the abandonment of summer fallowing, (3) the gen- 

 eral use of smut suction fans on thrashing machines, and (4) con- 

 sistent and universal seed treatment. 



There appears to be a possibility of being able to distinguish in 

 the field the two species of wheat bunt. Observations in Michigan 

 seem to confirm the impression that one of these appears in the 

 field as a " high smut," while the other breaks out lower down and is 

 called a " low smut." 



RUSTS OF CEREALS. 



Among other data, many facts have been accumulating during the 

 past three years concerning the relation of growth factors to rust 



