166 FRUIT CULTURE. 



serious form of fungus, both in its effect and 

 in tlie difficulty of destroying it. It is not 

 a surface feeder, but penetrates between the 

 cells of the vine tissues, sending up slender 

 mycelium threads on which the spores are 

 borne. These, by their multitude, form the 

 downy, frost-like patches on the under side of 

 the leaves and on the fruit, quite visible to 

 the naked eye. The injury to the foliage and 

 fruit is very apparent in the sultry season, 

 when the spores are thrown off and develop 

 with amazing rapidity. The fumes of sul- 

 phur, and also the copper solutions, will de- 

 stroy these summer spores and check the 

 spread of the fungus ; but they do not reach 

 beneath the surface to affect the parent plant. 

 Hence the importance of early spring spraj-- 

 ing, in order to intercept the second form of 

 spores which have been preserved through the 

 winter. It has been demonstrated both in 

 France and in this country that the Bordeaux 

 mixture is an effectual remedy, if applied early 

 in the spring, to intercept the winter spores, 

 and continuously thereafter every week or 

 ten days until about the first of August. The 

 objection to this mixture is that it is difficult 

 to strain the lime so as to prevent its clogging 

 the cyclone nozzle which gives the fine spray. 

 The lime is liable to stain the fruit. jManjr ex- 



