282 MANUAL OF FRUIT DISEASES 
considerable influence on the disease. In the Pacific North- 
west, for example, little or no curl exists east of the Cascade 
Mountains, where the annual rainfall is light; on the other 
hand, west of these mountains the rainfall is heavy and curl 
is very destructive. In these two regions the temperature 
is approximately the same. 
Control. 
The time and thoroughness of the application of remedial 
measures are important points in the control of peach leaf- 
curl. It is imperative that such work be done before the buds 
swell in the spring. Conjectures with reference to the winter 
and spring activities of the pathogene lead one to infer that 
spraying should prevent the disease. It has been shown that 
the application of almost any common fungicide ordinarily 
controls the trouble satisfactorily. One spraying is sufficient and 
may be made in the fall, or in the spring before the buds swell. 
Never spray more than once, as it is a waste of time and materi- 
als: and do not spray for curl after the leaves are expanded, for 
such an operation is useless and dangerous. Spray thoroughly, 
making sure to coat every bud. If the season is favorable to 
curl, the unsprayed buds will show the disease. Ordinarily 
lime-sulfur solution of standard Baumé test, 32°, at a strength 
of 1 to 15 or 1 to 20, is effective. If San José scale must be 
combated, both troubles may be controlled by using the fun- 
gicide at scale strength, 1 to 8. Scale can be controlled as 
effectively by spraying in the fall as in the spring. Bordeaux 
mixture of any strength, or copper sulfate 2 pounds to 50 
gallons of water, are also effective in controlling peach leaf- 
curl, and may be used when scale is not a factor to be considered. 
REFERENCES 
Reddick, D., and Toan, L. A. Fall spraying for peach leaf curl. 
Cornell Univ. Agr. Exp. Sta. Cire. 31: 65-73. 1915. 
Pierce, N. B. Peach leaf curl, its nature and treatment. U.S. Agr. 
Dept. Veg. Phys. and Path. Div. Bul. 20: 1-204. 1900. 
