Diseases of Plum, Peach and Cherry. 233 



DISEASES OF PLUM, PEACH AND CHERRY. 

 By Carl P. Hartley. 



These stone fruits are closely related and subject to the attacks of 

 very much the same fungi. I shall consider only those diseases which 

 have been or are likely to be commercially important in the vicinity. 



LEAF-CURL (Exoascus deformans). 



This disease is very destructive in some parts of the United States, 

 and is present in considerable, though not in very alarming, quantities 

 near Lincoln. The portions of the leaves which are atta'cked are 

 iypertrophied and curled, and a tree maybe enbirely defoliated. Uhe 

 mycelium may live thru the winter in the twigs and infect the leaves 

 of the next year; or the spores contained in the dead leaves from the 

 year before may infect the young leaves just at the commencement of 

 growth. It is quite well established that the fungus can prosper only 

 in young leaves whose growth has by unfavorable weather conditions 

 been temporarily arrested. 



TREATMENT. 



It was for a while supposed that because of the perennial mycelium 

 in the twigs the diseases could not be controlled by spraying. But ex- 

 periments conducted by the Department of Agriculture in California 

 and elsewhere during the period from 1894 to 1900 seem to have pretty 

 thoroughly exploded this idea. In one extensive experiment from 

 95 to 98 per cent of the foliage was saved by spraying. The recom- 

 mendation of the book on leaf-curl, published by the Department in 

 1900, was for spraying once or twice during March with strong Bor- 

 deaux mixture, using five pounds of copper sulphate and five pounds of 

 lime to the barrel; the object is to have the trees heavily covered with 

 fungicide at the beginning of growth. Pruning off affected leaves are 

 ^Iso commonly recommended. 



