48 BULLETIN 1256, U. S. DEPARTMENT OF AGRICULTURE. 



necessarily by high moisture content of the tobacco, although the 

 relation of moisture is not yet fully understood. The character of 

 the tobacco leaf itself, as regards various factors resulting from 

 growth and method of handling, probably plays some part in its 

 predisposition to musting. The presence of air in packed tobacco 

 also seems to favor musting, so that loosely packed leaf seems more 

 likely to become affected, especially if the humidity in the warehouse 

 is high. 



True musts are caused by a group of extremely small organisms 

 of the fungous type. More than one species seem to be involved. 

 Oospora nicotianae or very similar species and in some cases Actino- 

 myces are responsible. Some of these organisms grown on tobacco 

 or other media have an extremely musty odor. 



Molds due to other fungi are also found on tobacco, but less 

 commonly and usually only under exceptionally undesirable condi- 

 tions of handling and storage. A condition sometimes mistaken 

 for must or mold on tobacco is the excretion of a white salt (usually 

 saltpeter) on the midrib and veins of the leaf. This is of a less 

 harmful nature than musts or molds and is readily brushed off 

 without injurious odors remaining. This condition apparently re- 

 sults when the leaves are subjected to more or less rapid drying 

 under certain conditions. The character of the soil upon which 

 the leaf is grown seems to influence the occurrence of saltpeter to 

 a considerable extent, and it is more or less characteristic on tobacco 

 of certain districts. 



The prevention of musting of tobacco is not satisfactorily under- 

 stood. The avoidance of conditions previously mentioned as fav- 

 orable to it only can be advised. When tobacco has become musted 

 some packers resort to brushing off the musty color, redampening 

 the leaf with water or acetic-acid (vinegar) solution (about 4 per 

 cent), and repacking with the hope that a second fermentation may 

 be started and the undesirable odor partly removed. 



DISEASES OF TOBACCO IN FOREIGN COUNTRIES. 



Tobacco is grown under a wide range of conditions in various 

 parts of the world, although more than one-third of the total world 

 production is in the United States. The other principal countries 

 growing tobacco are India, Kussia, Sumatra, Java, Hungary, 

 Japan, the Philippine Islands. Germany, Cuba, France, Italy, Tur- 

 key. Brazil, and South Africa. To this list may be added Mexico, 

 Porto Rico, Canada, China, Rumania, Serbia, Bulgaria, Greece, 

 Belgium, and several other countries growing more than 5,000 acres. 

 The diseases of tobacco which occur in these countries are of some 

 interest to the producer in the United States, since with increasingly 

 close commercial relations the importation of new and dangerous 

 parasites is not at all unlikely. It seems quite probable that at 

 least some of our diseases of tobacco have been introduced from 

 foreign countries. A few diseases described in foreign literature 

 are not yet known to exist in this country, and these should espe- 

 cially be guarded against. 



Many of the foreign countries have investigated their plant dis- 

 eases in little or no detail, so that serious troubles may exist about 

 which* we at present know nothing. It is also true that diseases 



