78 BOARD OF AGRICULTURE. [Pul). Doc. 



1)0 iillowed to exceed 1 lO'^ F. at most. The green leaf is killed 

 at freezing tejnperatnres and the curing process is practically 

 stopped at temperatures below 50° F. The proper conditions 

 of tem])eralure and moisture are the principal requirements 

 for good curing. All growers in this section know how in- 

 jurious the cold northwest winds are to tobacco in the curing 

 barn, and this is because the temperature drops too low for 

 good curing, and, also, the water is evaporated from the 

 tobacco too rapidly. The leaf dries out but does not cure. 



Pole Sweat. 

 The importance of not allowing tobacco to dry out too 

 rapidly during the yellowing period has been emphasized, 

 but, on the other hand, growers well know what happens in 

 prolonged periods of warm wet weather if the tobacco has 

 already yellowed. The disease known as pole sweat is merely 

 a decay of the dead leaf, and is caused by lower organisms, so- 

 called " germs," which tind in the leaf their food supply. 

 Like the tobacco plant itself, these organisms, which are really 

 minute plants, must have an abnndance of moistnre to grow 

 rapidly, and they flourish only within certain limits of tem- 

 perature. Our experiments have shown that pole sweat be- 

 comes serious when the relative humidity of the air between 

 the curing leaves reaches 1)0 per cent or more, causing them 

 to become soggy, and when the temperature lies between 00° 

 and 100° F. After the disease has gained a foothold, a nuich 

 lower humidity or greater extremes of temperature are re- 

 quired to check it promptly. It is important to remend)er, 

 however, that pole sweat does not set in till the first and prin- 

 cipal stage of the curing has been completed, which is ordi- 

 narily indicated by the yellowing of the leaf, for only the 

 dead portions of the leaf are attacked. One of the common 

 forerunners of pole sweat is the so-called "' strut " of the leaf, 

 which is a stiffening of the veins and midrib, caused by the 

 excessive moisture in the air having checked the evaporation 

 from the leaf. The strut or stiffening indicates danger from 

 sweat, but really does not i)lay any ])art in the development of 

 the disease, although it does injure the tobacco. It is simply a 

 sign of too much moisture. 



