PEACH LEAF-CURL AND NOTES ON THE 

 SHOT-HOLE EFFECT OF PEACHES AND 



PLUMS. 



I. Peach Leaf-Curl.* 

 a. General Remarks. 



In bulletin 73 of this Experiment Station a complete account 

 was given of the fungi causing leaf-curl and plum-pockets on 

 many members of the genus Prunus. In the present discussion 

 of the leaf-curl of the peach it will be unnecessary to go into 

 technical details; but in order, as far as possible, to have a reason 

 for that which is done, or recommended, a general account of the 

 life history of the fungus must be included. 



Peach leaf-curl is a disease which has long been known to the 

 orchardist as well as to the botanist ; and since the seasons of 

 1897 and 1898, there are probably very few peach growers in the 

 state who are unfamiliar with the disease. The inquiries 

 received during the past spring concerning this disease were so 

 numerous that it has seemed important to give to the growers 

 the results of the work of a single season, along with those 

 results which have been elsewhere obtained. Many of the 

 inquiries have sought a remedy onl}-, but still others have 

 desired a knowledge of the cause; and a general treatment of the 

 subject is necessary. 



b. Appearance of the Disease. 



Peach leaves affected with the curl can often be detected as 

 soon as the leaf buds have opened to a slight extent A 

 roughened surface of the 5'oung leaf, and an excess of coloring 

 are usualh^ the first indications. As the 3^oung leaves rapidly 

 assume their normal size, this curling and arching of the blades 

 is more prominent. Sometimes there is distortion in a small area 

 only, and again the entire blade may be affected. The curling 

 of the edges of the leaves may be upward or downward, or the 



"^ Exoasctis deformans (Berk.) Fuckel. 



