Feb. i8, 1918 Tobacco Wildfire 457 



dissemination of wildfire by fertilizer materials. Attempts to isolate 

 Bad. tahacum from diseased leaves which had passed through the curing 

 process gave negative results in the case of three samples tested. In 

 view of the fact that no growth occurred in bouillon cultures exposed to 

 temperatures above 65° C. for 10 minutes, as has previously been reported, 

 it is highly improbable that the organism could survive for several hours 

 temperatures of 180° F. and above, as are maintained for several hours 

 in the last part of the curing process. Furthermore, in the preparation 

 of tobacco stems for incorporation with fertilizer materials they are sub- 

 jected to a sufl&cient degree of heat to insure complete sterilization. 



SUMMARY 



(i) A leafspot disease of tobacco called "wildfire," which is more 

 destructive than any other malady affecting this crop, has appeared 

 within North Carolina and Virginia. 



(2) It has been collected during the past season in 19 counties within 

 North Carolina, 3 within Virginia, and occurs also in Wisconsin. 



(3) Wildfire first attracted attention at time of transplanting tobacco 

 and appeared again in epidemic form at time of topping the crop. 



(4) The disease originated in the seed bed or plant bed, but only nega- 

 tive evidence had been secured that infection comes from the seed. 



(5) The leaves alone are attacked, and the symptoms are entirely 

 unlike those of other foliage disease of tobacco. 



(6) The primary cause of wildfire has been found to be a wet-shining 

 grayish white, i -flagellate organism, which is herein described as Bac- 

 terium tahacum. Its period of incubation is about 72 hours, and large 

 lesions are formed within a week. 



(7) The disease is of the necrotic type, involving parenchyma tissues. 



(8) Moisture is of prime importance in the spread of wildfire. When 

 rains are accompanied by wind, dissemination is especially rapid. 



