TOBACCO DISEASES AND THEIR CONTROL. 



43 



DAMAGE IN CURING AND FERMENTATION. 



The diseases of tobacco previously described have been concerned 

 with maladies affecting the living piant and are either of a parasitic 

 or nonparasitic origin. Following harvest, the tobacco leaves must 

 first go through a curing process which consists essentially of a more 

 or less rapid drying and consequently death of the leaf tissue itself. 

 The conditions of curing, fermentation, and storage of the various 

 types of tobacco must be such as are most conducive to the proper 

 color, body, texture, elasticity, grain, burn, and other factors which 

 make up quality for the individual types. Any distinctive abnor- 

 malities from the desired result in these processes are naturally of 

 as much concern as abnormalities of the growing plant and conse- 

 quently must receive at- 

 tention as to cause and 

 control measures. For the 

 most part the damage in 

 curing, fermentation, and 

 storage is the result of the 

 action of undesirable mi- 

 croorganisms under con- 

 ditions favorable for 

 their development. These 

 organisms belong to the 

 class of saprophytes rather 

 than the parasites, since 

 they act ordinarily on 

 dead tissues only, in 

 which they tend to pro- 

 duce decay. In this con- 

 nection it is well to re- 

 member that the decay 

 and final disappearance 

 of all organic matter is 

 dependent upon the ac- 

 tion of such organisms 

 and that any method 

 which eliminates their 

 presence completely, such 

 as sterilization, or which renders conditions unfavorable for their 

 development can be relied upon to preserve most such materials in- 

 definitely. 



The most common forms of damage in tobacco following harvest 

 are shed-burn or pole-rot, stem-rot, wet-butts (or fat-stem), white 

 veins, black-rot, must, and molds. These injuries will be taken up in 

 the approximate order of their occurrence. 



SHED-BURN OR POLE-ROT. 



Description, — This damage is also known under the name of pole- 

 burn and pole-sweat. It is characterized in mild cases by the darken- 

 ing and the tendency of the leaf to dry out rapidly and to become 

 harsh and brittle, together with loss of elastic strength. In more 

 severe cases the body of the leaf is actually decayed, so that affected 

 spots appear dark by reflected light but transmit light more readily 



Fig. 24. — Jack-in-the-pulpit effect of a leaf growth in 

 the bud of a tobacco plant, illustrating rare phe- 

 nomena of the monstrosity class. 



