DAXGEROUS TOBACCO DISEASE APPEARS IN UNITED STATES. 5 



or Gulf seaboard, since a search through the collections of the Na- 

 tional Herbarium shows Xicotmiia glauca to have been collected at 

 Camden, X. J. (1897), Quarantine Station, S. C. (1889), and several 

 times at Pensacola, Fla. (1880, 1897, 1903, etc.). 



The rapid spread of the disease through the Florida-Georgia area 

 is easily explained. The fungous spores are produced in great num- 

 bers, and are dry. powdery, and very light, and the weather condi- 

 tions were ideal. Observation indicates unquestionably that a large 

 part of this spread of the disease from bed to bed has been through 

 the agency of visitors going from infected beds to healthy beds, car- 

 rying the spores on their feet and clothing. The spread through any 

 particular bed is undoubtedly due largely to the agency of the wind. 

 It is probable also that some of the spreading from bed to bed has 

 been brought about through the agency of the wind. 



The outcome of this mildew disease in the United States can not 

 now be predicted, but it is likely that the long-suffering tobacco 

 grower will, from now on, have to contend with another destructive 

 disease and that he can only succeed in growing tobacco successfully 

 when he uses all the methods at his command for controlling the 

 enemy, namely, beds of sterilized soil, seed of undoubted purity, and 

 hygienic measures in the care of the seedlings, so that the disease 

 can not be introduced from other beds into his beds. To this end 

 the beds should be separated from each other as widely as possible 

 and visitors should he rigidly excluded. 



A very important question arises immediately as to whether it is 

 safe for planters to set out from diseased seed beds the remaining 

 apparently sound seedlings. In Australia the bulk of the disease has 

 been always in the seed beds. Diseased plants transplanted to the 

 fields have in the course of time died and have not generally trans- 

 mitted the disease to plants that were healthy when set out, but it must 

 be remembered in this connection that the Australian climate is a 

 much drier climate than our own Florida climate and also that the 

 tobacco grown in Australia is grown in the open, whereas the fine 

 wrapper tobacco of Florida is grown under expensive lath or cloth 

 shade, which increases the moisture conditions very decidedly over 

 plants grown in the open. It is to be noted in this connection that 

 when a disease is introduced into a foreign country it very often does 

 much more serious damage than it did in its original home, so that 

 taking all the facts into consideration it seems to us very unsafe to 

 plant any of these shaded fields with seedlings from infected beds. 

 In fact, we think it would be better to abandon the culture of tobacco 

 in these shaded fields for this year where it is not possible to set with 

 plants that are known to be healthy. Such fields should be planted 

 to corn or some other crop not subject to the parasite rather than run 



