224 Journal of Agricultural Research voi. xvi, no. s 



The records of one inoculation series are given (Table II) chiefly to 

 show the vertical distribution of the spots with reference to the position 

 of the leaves and their relative ages. These plants were inoculated on 

 January i6, 191 8, with an atomizer containing an aqueous suspension 

 of a strain of the angular-leafspot organism isolated from material from 

 Republican Grove, Va., on August 10. The plants were covered with 

 moist chambers for 12 hours subsequent to inoculation. They were at 

 the blooming stage and were topped just before inoculation. The spots 

 were first visible on January 22, and the coimts were made on February i. 



Table II shows that the spots were about equally distributed over the 

 first, second, and third leaves, with a few on the fourth leaves and none 

 on those older and lower on the stem. Flecks developed on the fourth 

 and fifth leaves, but not on younger or older leaves. 



COMPARISON OF ANGULAR-LBAFSPOT WITH OTHER LEAFSPOTS OF 



TOBACCO 



The angular-leafspot can not be assigned with certainty to any of the 

 previously described tobacco leaf spots of bacterial causation. It has 

 some features in common with the "whitespot" of Delacroix {2, 3),^ 

 caused by Bacillus maculicola Del., but the descriptions of this disease 

 and of the organism are too meager to afiford an adequate basis for com- 

 parison. "Blackrust," a disease of Deli tobacco described by Honing 

 (4), differs from angular-leafspot in several important features, and the 

 causative organism. Bacterium pseudozoogloeae Honing, is readily distin- 

 guished from the angular-leafspot organism. 



The spot which Wolf and Foster (7) have recently described under the 

 name "wildfire" from North Carolina appears to differ strikingly from 

 the disease under discussion. The most noteworthy points of difference 

 being found in the broad, distinct halo which borders the wildfire spots, 

 in their circular form and zonated interior, and in size. Wildfire spots 

 are 2 to 3 cm. in diameter, while those of the angular-leafspot are only 

 4 mm., on the average. Some contrasting features between Bacterium 

 tabacum Wolf and Foster, the wildfire organism, and the angular-leafspot 

 organism are given in Table III. Features in common between the two 

 diseases are found in their sudden appearance and rapidity of spread, 

 and in the relation between rainfall and epiphytotics, although this seems 

 a common feature of bacterial leafspots of tobacco. It seems quite 

 probable that the disease to which Wolf and Foster refer as "speck" is 

 identical with our angular-leafspot. They state that speck is caused by 

 a lack of potash. 



' Reference is made by number (italic) to "Literature cited," p. 227-128. 



