TOBACCO DISEASES AND THEIR CONTROL. 47 



Conditions favoring attack'. — The extent of damage from black-rot 

 will ordinarily vary with the number and distribution of the spores 

 of the causal organism present and the favorableness of the condi- 

 tions for their development. Moisture is naturally essential for 

 growth, and as a matter of practical importance the percentage of 

 water present in the fermenting tobacco is the most important consid- 

 eration in damage from black-rot. The high temperatures produced 

 by fermentation, together with a relatively high moisture content of 

 the leaf, make an especially favorable condition for black-rot to 

 develop. It has been found that black-rot can not occur above 110° 

 F., since the rot fungus can no longer grow above that temperature. 



Control. — The control of black-rot must center around either 

 reducing the moisture in tobacco to an amount necessary only for 

 proper fermentation or raising the temperature of fermentation as 

 rapidly as possible to around 110° F. or above. With the object 

 of keeping the moisture content down, growers should be advised 

 not to permit tobacco to come into too high case when taken down 

 in the shed. TVhen high-case crops are received in the warehouses 

 they should preferably be assorted and packed as late in the sorting 

 season as possible or bulk fermentation carried out before packing 

 in cases. Bulk fermentation usually permits temperatures as high 

 as 110° to 120° F. being reached in a few days, hence is unfavorable 

 for black-rot, and the accompanying turning of the warm tobacco in 

 the bulk is especially favorable for reducing its percentage of mois- 

 ture before packing in boxes. The number of rebulkings should 

 depend somewhat, therefore, on the amount of moisture in the to- 

 bacco, in order that it may be brought down to a desirable moisture 

 content before being packed in storage. 



The alternative of packing directly into the boxes and storing at 

 once in room temperatures as high as 110° F. suggests itself. This 

 method has not been satisfactorily tested, as far as known. Earlier 

 methods of force sweating in boxes were usually at lower tempera- 

 tures and not satisfactory. Finally, it is not at all improbable that 

 cigar tobaccos may be passed through drying or " reordering " ma- 

 chines, which will not only reduce danger of damage but tend to 

 produce a more uniform product in general. 



MUSTS AND MOLDS. 



True tobacco musts are characterized by a white powderlike growth 

 over the surface of the leaves during fermentation or storage (PI. 

 XVII, fig. 2). No true decay occurs, nor is the leaf ordinarily 

 injured in an} T way excepting in appearance and in aroma. A musty 

 odor accompanies this damage, which it is practically impossible to 

 remove satisfactorily, and consequently affected tobacco is much 

 reduced in value. This trouble is fairly common upon fermenting 

 or stored cigar tobaccos. It does not ordinarily seem to be asso- 

 ciated with black-rot in the same packings, and consequently the 

 conditions favoring the two are apparently different in one or more 

 respects. Practical observations indicate that when certain types 

 of tobacco lie for several weeks in boxes before going into active 

 fermentation, mustiness is likely to appear. Similarly, mustiness 

 may develop following fermentation in storage. Mustiness is not 

 favored particularly by the high temperatures of fermentation nor 



