160 BOARD OF AGRICULTURE. [Pub. Doc. 



Again, in localities that have a dry season throughout the 

 period of growth, these maladies are not prevalent. The 

 effect of an awning of boards or cloth over a single trellis in 

 a vineyard is a complete protection to the foliage and fruit 

 underneath it, even where that of the vines on either side is 

 destroyed. This is not because the covering prevents the 

 deposition of the spores floating in the atmosphere, but for 

 the reason that no water from rains and more especially from 

 the deposit of dew can take place under such protection. 

 Rain is probably not nearly so favorable for the spread and 

 propagation of fungous spores as are dews and fogs. The 

 effect of rains is most likely to remove the spores by wash- 

 ing them off upon the ground before germination, where they 

 can do no harm until by drying out they may be in condition 

 to renew their aerial flight. The effect that follows the 

 enclosure of grape clusters in paper bags goes to prove 

 the same thing. If this operation be performed before the 

 germination of the spores of mildew or rot, the clusters are 

 perfectly protected throughout the worst season; but, if it is 

 done only one day too late, the protection is of little or no 

 avail. 



Many years ago sulphur was looked upon as a sovereign 

 remedy for most of these mildews and blights. Perhaps this 

 idea arose out of the theological teaching of the times; but 

 in both cases it has been learned that it is ill adapted for the 

 highest ends, while other appliances have been found to be 

 an adequate and preferable substitute. As the matter stands 

 to-day, the agent which surpasses all others in the effective 

 treatment of fungi in general is found in some form of solution 

 containing copper. Other substances, such as soluble arsenic 

 and corrosive sublimate, are known to be valuable for the 

 purpose ; but no one combines within itself so many good 

 qualities, and we can hardly ask for one that will give more 

 satisfaction in its effects. It is very cheap, in no way 

 dangerous to use, easily applied; and while, when properly 

 used, it does no injury to cultivated plants, it is preeminently 

 destructive to man}' if not most forms of fungi. One part 

 of copper in solution in upwards of a million parts of water 

 will entirely prevent the development and growth of these 

 minute organisms when Immersed in it, and a stronger solution 

 will undoubtedly kill the spores. 



