DRUPACEOUS FRUITS 127 



to the popular name of curl. This fungus destroys the 

 utility of the leaf as a starch-producing organ, and even- 

 tually causes defoliation, and thus direct loss to the trees. 

 This loss may be manifest in two ways : first, by the pres- 

 ent effect upon the vitality and vigor of the tree, and im- 

 mediate injury to the crop ; second, by a weakening of the 

 tree in succeeding years, due to the lack of full nourishment 

 during the period of attack. The injury in the present 

 year, manifest by a loss in productiveness, is obvious to the 

 grower. The injury in succeeding years, often fully as 

 great, is frequently overlooked, or is not attributed to its 

 true cause. 



It was formerly thought that this fungus persisted in the 

 twigs over winter, and thus lurked ready to infect the new 

 leaves as they began to develop. It has, however, been 

 proved that nearly, if not quite, all spring infection is due, 

 not to perennial mycelium, but to spores which remain on 

 the bark of the trees. 



Prevention of the disorder lies in killing these spores of 

 the fungus by winter spraying. For this purpose Bordeaux 

 mixture, the lime-sulphur, or a simple copper sulphate 

 solution is efScient. In many ways the Bordeaux is more 

 satisfactory than the copper sulphate solution. It does not 

 have as strong corrosive action upon the pump. It is easily 

 seen upon the trees, and consequently it is not difficult to 

 determine when a thorough application has been made. 

 There is probably little choice between these two solutions 

 on the ground of efficiency. The lime-sulphur is preferable 

 when insects also are to be met. The spraying should be 

 made from one to three weeks before the buds open in the 

 spring, and thoroughness is the chief point desired. Spray- 



