CERTAIN ELEMENTS IN NURSERY PRACTICE 203 



PEACH LEAF-CURL. Peach leaf-curl is distinctly peculiar 

 to the peach and to forms derived from it, such as the nectarine. 

 In the nursery the damage caused by the leaf-curl is particularly 

 noticeable from the fact that the young trees are affected 

 when in the most critical stage of development, just as the 

 grafted buds start to grow in the spring. A large proportion 

 of affected buds fail to de- 

 velop into first-class trees. 



Different varieties grown 

 under similar conditions 

 show marked differences in 

 susceptibility to the disease ; 

 however, there is consider- 

 able variation in the sus- 

 ceptibility of any particular 

 variety when grown under 

 diverse conditions. Usually 

 the Carman and Elberta 

 show less resistance than 

 most varieties. 



Description. The first 

 evidence of the disease is the 

 arching and reddening of the 

 affected areas in the young 

 unfolded leaves as they be- 

 gin to protrude from the opening bud-scales. The lesions may 

 be confined to a part of the blade or the petiole, or they may 

 involve the entire leaf and extend into the twig (Fig. 217). 

 The diseased parts are thick and brittle, causing a consider- 

 able increase in weight of the affected leaves. With the 

 maturation of the leaves, the pale yellow or red color dis- 

 appears and the hypertrophied area on the upper surface 

 becomes silvery in appearance. The first leaves to expand are 

 usually the most affected, and the curled leaves finally die and 



