12 PEACH LEAF CURL: ITS NATURE AND TREATMENT. 



GENERAL CHARACTERISTICS OF THE DISEASE. 



The disease of peach trees here considered is variously known in 

 different regions and languages. In the United States it is commonly 

 know as peach leaf curl, or curl leaf of the peach; in England and 

 all British possessions, as leaf blister, leaf curl, or curly leaf; in 

 France, as cloque du pecher; in Germany, as Kriluselkrankheit; in 

 Italy, as Fillorissema, etc. 



Peach leaf curl is a disease which seriously affects the leaves, flowers, 

 tender shoots, and fruit of the peach. Its action is most severe in the 

 spring of the year, shortly after the leafing of the trees, and the greatest 

 injuries are caused in wet seasons and in humid localities. The leaves 

 become enlarged, thickened, nmch curled, and distorted. As the dis- 

 ease progresses the healthful green of the foliage is changed to a yel- 

 lowish, sickly appearance. The leaves soon fall, and the newly formed 

 fruit ceases to grow, yellows, wilts, and likewise falls. The total loss 

 of foliage and crop is common in seasons favorable to the disease. A 

 second growth of leaves develops more or less rapidly, according to 

 the severity of the disease and the favorable or unfavorable soil and 

 atmospheric conditions prevailing at the time. If the soil and atmos- 

 phere are dry and the temperature high, new foliage may appear slowly 

 and much of the terminal growth may die throughout the orchard. In 

 severe attacks young trees are frequently killed. The second crop of 

 leaves, appearing on affected trees after the spring defoliation, usually 

 remains comparatively free from curl for the rest of the season. The 

 amount of disease which will appear upon this later crop of foliage 

 depends largely upon the humidity or dryness of the atmosphere, 

 excessive moisture favoring a continuance of the trouble. The action 

 of the disease upon spring l)ranches causes them to enlarge, become 

 curved and distorted in various ways, and often to dry up and die. 



GEOGRAPHIC DISTRIBUTION. 



Peach leaf curl exists in most peach-growing countries. Its distri- 

 bution in the United States extends from the Gulf of Mexico to Can- 

 ada and from the Atlantic to the Pacific. The centers of greatest 

 prevalence, and where the greatest losses are sustained from this cause, 

 are in the leading peach-growing districts bordering the Great Lakes, 

 especially in Michigan and western New York; in the central, north- 

 ern, and coast regions of California; and west of the Cascade Moun- 

 tains in Oregon and Washington. The disease is less serious, or is of 

 minor importance, in those peach-growing counties of New York 

 most distant from the lakes, in Pennsylvania, Ohio, Indiana, Illinois, 

 and in southern California. Still less injury is reported from New 

 Jersey, Delaware, Connecticut, Rhode Island, Massachusetts, Mary- 



