Spraying Notes. 271 



ticides that one must always be cautious when spraying this class of 

 fruit. The apparently increasing susceptibility of the Japanese 

 plums to the fruit rot (monilia) makes it essential to take some pre- 

 ventive measure. It cannot be said that spraying is always an abso- 

 lute specilic for the fruit rot. In a wet season no advantage may 

 be noted. Through a series of years, however, a faithful combina- 

 tion of spraying, thinning the fruit and destroying the diseased 

 fruit can be depended upon to prevent serious injury. 



The standard fungicide for the Japanese plums is Bordeaux 

 mixture. Bulletin 164 contains an account of the shot-hole effect 

 produced by Bordeaux on plums and peaches. Tiiis injury has been 

 observed for several years as resulting from even the most carefully 

 prepared Bordeaux. During the past season, experiments were 

 made to determine the effect of copper carbonate and potassium 

 sulfide on Japanese plum foliage. The copper carbonate was 

 applied in an ammoniacal solution at the usual strength : the potas- 

 sium sulhde at the rate of one ounce to a gallon of water. Both 

 were slightly more injurious to the foliage than Bordeaux. Since it 

 is not probable that either has a greater fungicidal value than 

 Bordeaux, there can be no advantage in displacing the older 

 fungicide. 



The effect of copper sulfate on foliage. — It would be difficult to 

 find a material of greater fungicidal value than Bordeaux mixture, 

 yet it becomes a practical point to combine the same efficiency with 

 greater ease in application and less danger of injury to the foliage. 

 Those who have used a solution of copper sulfate find it to be an 

 excellent fungicide. From laboratory studies we know that a very 

 weak solution of blue vitriol will prevent the germination of fungi 

 spores, but it is a question if it will have the same value under the 

 conditions of orchard and field. 



It is of importance to know whether the foliage will be injured 

 by a solution strong enough to be an efficient fungicide. The 

 spraying in our test of this point was done May 24, and the final 

 records taken June 10, The barrel reported below holds 48 gallons. 



