272 



Bulletin 177. 



TABLE III. 

 Injury to Foliage From Copper Sulfate Sprays. 



Although no severe injury to the native plums is recorded in the 

 table, it was incidentally brought out that there is considerable 

 variation between the different varieties of this group in their 

 susceptibility to injury. The variety under experiment was Golden 

 Beauty. Some spray accidentally reached the leaves of an adjacent 

 Munson and there caused serious injury. 



Most of the injury noted was in the spotting of the leaves. 

 Wherever the fungicide clung, there the tissue was killed and 

 ultimately fell out, producing a condition which might readily be 

 mistaken for the effect of the shot-hole fungus. When copper 

 sulfate was applied to peaches and domestic plums at the rate of 

 2 lbs. per bbl., these perforations were so numerous that many leaves 

 dropped. The young fruits of the Japanese plums were injured by 

 the two strongest sprays. 



These tests do not throw any light on the value of copper sulfate 

 for controlling plant diseases; they simply indicate that unless care- 

 ful discrimination is made between varieties, only a very weak solu- 

 tion can be used with safety to the foliage. Until the simple solution 

 of copper sulfate has been tested further, there is no safer or surer 

 orchard fungicide than well made Bordeaux mixture. On Japanese 

 plums, apply it weak. It would be w^ell to experiment in applying 

 it only in bright weather. 



