5^0 Journal of Agricultural Research voi. xvni, no. io 



Gelatin is liquified; milk becomes alkaline and translucent but does not coagulate; 

 nitrates not reduced; acids produced from saccharose, dextrose, and galactose. No 

 gas produced. Gram-negative. Group number 221.2322123. 



Pathogenic to Triticum vulgare, causing especially discoloration and lesions at the 

 base of glumes and kernels. 



INOCULATIONS 



Inoculations on young wheat plants have given numerous leaf infec- 

 tions (PI. 62, D). Fewer mature plants have been available for inocu- 

 lation of heads, and weather conditions were rather unfavorable; but 

 enough infections were secured to determine the positive pathogenicity 

 of the organism for glumes (PI. 62, E, F) and kernels. 



For the leaf inoculations bacteria from agar subcultures were mixed 

 with sterile water and sprayed on the plants with an atomizer. The 

 infections are stomatal. On the second day after the inoculation, dark, 

 water-soaked spots appear. These are small and well distributed over 

 the leaf surface. Two days later the spots are pale yellow. They en- 

 large and also elongate slightly. Later the color is light brown and the 

 tissues are dry. 



Sometimes bacteria were added directly to drops of condensation 

 water on the leaf tips. In these inoculations the whole tip of the leaf 

 became yellowish brown and shriveled. If examined at the end of five 

 or six days the bacteria are abundant in the tissues. From the leaf infec- 

 tions (more than 50 series of successful inoculations) the organism 

 was reisolated 22 times and often used again, producing typical infections. 



For inoculating the heads of wheat, bacteria from agar subcultures 

 were diluted in sterile water and by means of a camel's hair brush were 

 spread over the glumes and between the spikelets of young heads just 

 emerging from the flag leaf. On some glumes a few slight wounds were 

 made with a fine needle. 



The infections (all done in Washington, D. C.) were slower in showing 

 on the heads than on the leaves. Glume discolorations were noted first on 

 the fourth day after inoculation. The spots enlarged slowly and never 

 became so noticeable as those on naturally infected heads. Examina- 

 tion after collection showed that the bacteria had penetrated to and into 

 the kernels, some of which showed the characteristic blackening at the 

 germ end and great abundance of bacteria in the spaces about the radicle. 

 The inner surface of the glumes also showed more discoloration than was 

 visible from the exterior. (See PI. 62, F, a.) 



The characteristic organism was reisolated from both the glumes and 

 the kernels of the inoculated heads and used again in a second series of 

 inoculations on heads and on leaves of seedling plants. The disease was 

 reproduced in both series, and the organisms were again isolated from each 



