1106 THE FRUIT INDUSTRY IN NEW YORK STATE 



appearance (Fig. 396). In severe cases of leaf spot, the folia* 

 very frequently turns yellow; hence it is called " yellow leaf.' 

 It is clear, then, that yellow leaf and leaf spot are names for tm 

 same disease. Infections on the Japanese varieties of plum ai 

 chiefly of a shot-hole nature, but there is practically no defoliatioi 

 as in the case of the European plum varieties. 



This disease is not confined to the plum, but may serious! 

 affect sweet and sour cherries, both wild and cultivated. It as 

 sumes great importance in the nursery and is destructive to trc 

 of plum and cherry orchards. 



FIG. 396. LEAF SPOT OF PLUM. NOTE THE GHOT-HOLE APPEARANCE 



The leaves are the chief organs attacked; however, the frui 

 and fruit stalks are not exempt. The spots appear at first 

 slightly discolored areas, usually not exceeding an eighth of 

 inch in diameter, and more commonly about half that size. Aft( 

 a week or ten days, the spots become very definite in outline, 

 assume a reddish-brown color. In wet weather, small white 

 velvety pustules are abserved on the lower surfaces of the leav< 

 opposite the discolored spots. These pustules occasionally omn 



