FRUIT TREES. Chap. V. 101 



it produces gummosis that often doesn't cause them any harm. But when this extruded 

 sap gets into the lymphatic vessels, it results in dangerous obstructions. Loss or 

 deterioration of the part above this gummy deposit indicates that prompt treatment is 

 necessary. This is easy when the disease has affected only the branches; they're cut off to 

 about an inch below the deposit. But if it has attacked the trunk, it can't be cured. 



3°. Peach leaf curl is a specific disease of leaves of the peach tree. In the spring 

 they become wrinkled, distorted, and shrivel up. Their tissue thickens, the surface appears 

 granular & scabby, and their color turns a mixture of whitish, yellow, and red. The 

 disease attacks not only the leaves that clump into hairy tufts, but the ends of the shoots 

 as well that swell up considerably & take on the same coloration. This disorder comes on 

 in a few days, & soon it's followed by another one. A horde of aphids settles into the 

 swellings or into the hollows of the leaves & attracts ants. The outcome is that all of the 

 products of the tree, its shoots, leaves, & fruit, are disfigured & suffer greatly from this 

 complex of ills. 



Gardeners attribute peach leaf curl to reddening winds, but this term needs to be 

 explained [Translator r s note: vents roux is an agricultural term for cold, dry winds that 

 blow from the north in the spring and turn young plants a russet or brown color]. Others 

 claim that it's brought on by the first rays of clear & warm sunshine after a cold dew. If 

 espalier peach trees facing west were free from peach leaf curl, this would seem 

 reasonable. But sometimes they're struck by it, even though the dew had vanished & the 

 air was warm for a long time before the sun reached them in this exposure. Aphids & ants 

 also are blamed, but none are visible during the first days. Besides, the disease is too 

 sudden & its progress is too rapid to be attributed to these insects alone. In fifteen days or 

 three weeks the withered leaves drop off by themselves & the tips of the damaged shoots 



