CHAPTEK XI. 



PESTS OF TOBACCO DISEASES, INSECTS, THE ELEMENTS. 



Following the chapter on curing, we will first dis- 

 cuss the troubles or diseases that are met with in curing 

 tobacco. Chief among these is pole burn. ''This trouble," 

 says E. S. Goff, "appears as dark spots near the mid- 

 rib or vein ; under favorable conditions it spreads rap- 

 idly, discoloring and rotting the whole leaf, and often 

 destroying the entire crop in 24 to 36 hours. It is 

 caused by two fungous enemies : First, a sort of mold, 

 which attacks the outside of the leaf and lays the inte- 

 rior open to the invasion of bacteria, which (second) 

 then develop rapidly, causing the principal mischief. 

 The development of the disease is chiefly controlled by 

 atmospheric conditions, being most probable in rather 

 warm, very humid air. A nearly cured, dry leaf is not 

 liable to attack. A temperature above 100 F., or below 

 40, greatly retards its activity ; but one of ?0-90 is 

 most favorable. If we can control moisture and tem- 

 perature conditions, we can prevent injury from this 

 otherwise menacing enemy." Examination shows that 

 the leaves have changed from a greenish -yellow to a 

 dark brown or almost black color, that the fine texture 

 has disappeared, and that instead of being tough and 

 elastic, the whole leaf is wet and soggy, and tears almost 

 with a touch, falling of its own weight from the stalk. 



Something has been done at the Wisconsin exper- 

 iment station to combat this disease (as described in the 

 preceding chapter), and considerable has been accom- 

 plished at the Connecticut station by Dr. W. C. Sturgis. 



