56 



MILDEW ON THE VINE. 



cold and wet. As soon as I observed it, I sprinkled 

 sulphur on the flue, and began firing it, keeping a cur- 

 rent of air as dry as possible in the house. I watched 

 the stems and thread-like links of the parasite on 

 the leaves and berries with a glass, and I found that 

 the current o'f dry air and fumes of the sulphur caused 

 them to shrivel up and die. The disease made no fur- 

 ther progress, and I believe it will never attack vines 

 that are grown in a proper climate. As to heat, moist- 

 ure, and ventilation, many treat their vines so as to 

 predispose them to it, or rather they bring about such 

 a climate as the mildew will grow in. It is not uncom- 

 mon for individuals to have some favourite day in June, 

 perhaps, when they give up firing their vinery. They 

 still continue the usual sprinkling with water, and shut 

 up the house with a stagnant atmosphere, loaded with 

 moisture ; and it often happens that cold nights reduce 

 the temperature of the vinery so low that the vital 

 energy of the vines is depressed, predisposing them to 

 disease, while they are in a climate well adapted to the 

 growth of fungi of any sort. To a careful attention to 

 the keeping up the proper degree of heat during the 

 whole forcing season, not too much moisture, and a 

 constant circulation of fresh air, I attribute the ex- 

 emption from vine mildew I have experienced when 

 vineries not five hundred yards off" had their crops 

 ruined by it. It has been supposed by some that the 

 mildew merely makes its appearance as the conse- 

 quence of a diseased condition of the tissues of the 

 vine ; but this I hold to be a mistake. The spores 

 of the parasite in question may exist in myriads on 

 every inch of the vine's surface and do it no harm, 

 unless the climate of the vinery is made to suit their 

 development, when they spring into life as if by magic, 



