2IO 



Grape- Culture. 



lime, but without any apparent difference in results. I have usually found 

 two applications all that was necessary in one season, — one about the time 

 of development of the first leaves in spring ; and the other near the close 

 of the strongest growth of the vine, — from the middle to the last of July. 

 This latter period is the time at which the oidium usually makes its appear- 

 ance ; and if the weather is such as to materially check the growth of i 

 vines by sudden alternations and low temperature, or by excessive cool 

 rain followed by hot sunshine, its effects are greatly increased, and the 



Fig. 2. 



a. Reservoir for sulphur, with three or four.holes leading into the escape-pipe d; part of which may 

 be closed with plugs, if necessary. 



h. Small valve opening outward, and which prevents sulphur from getting into the body of the bellows. 



c. Air-valve. 



d. Escape-pipe flattened laterally, spreading the sulphur as it escapes. Escape-pipe and reservoir 

 made of heavy tin. 



disease sometimes spreads with astonishing rapidity. Upon vines enfeebled 

 by an over-burden of fruit or other causes, the leaves often all fall prema- 

 turely, leaving only unripe fruit and green wood which can never mature. 

 The primary cause of oidhnn is still somewhat obscure ; and it does, not 

 appear to be definitely settled whether it is a cause of disease, or the 

 effect of a previously existing unhealthy condition. My own obsen-^ation 

 inclines me to belief in the former supposition ; for, in the atmospheric 

 conditions most favorable to its manifestation, vines in apparently perfect 

 health and vigor are by no means exempt from its attacks. In dry, warm 

 seasons, in locations of equable temperature, it has within my observation 

 rarely appeared ; while in wet seasons, especially when marked by great 

 variation of temperature, it almost invariably prevails. 



