DISEASES. 147 



that the main preventive of mildew is to keep the plants 

 in a steady and healthy action, not only by supplying a 

 due proportion of food moisture and heat according to their 

 constitutional requirements, but by preventing sudden 

 changes in the atmosphere with which they are sur<- 

 rounded, and particularly avoiding cold drafts in the lower 

 parts of the house. Heat accelerates the circulation, and 

 if the whole bulk of the air is uniformly heated, the circu- 

 lation will be equal in its action and distribution in every 

 part of the plant. 



In our practice, bottom air is not admitted until the fruit 

 begins to change color. Although the above remarks may 

 not harmonize with the opinions of others, an extensive 

 experience has convinced us of their correctness. 



We have then the whole matter in a " nutshell." 

 During the time when the vines are growing freely, keep 

 up a strong steady heat, avoid damp or cold drafts, and 

 south and east winds during cloudy weather or storms ; 

 keep the house closed in such cases: 



Be careful that the house is not suddenly heated up 

 when the sun breaks out, afterward regulate the moisture 

 according to the external atmosphere. Close early in the 

 evening, and open early in the morning. Observe and 

 remember that to counteract the effects of sudden changes 

 in the atmosphere is the great desideratum. The best of 

 us may sometimes find our utmost skill tested, but a per- 

 severance in the course here marked out with close 

 attention will overcome all difficulties, and we will be 

 amply repaid for all our trouble. 



Many think that when mildew makes its appearance 

 sulphur is the only antidote, without anything further than 

 merely dusting the affected parts, or strewing a portion 

 over the floor. From our previous remarks it will be seen, 

 that this will sometimes be sufficient, but it is not merely 



