340 MANUAL OF FRUIT DISEASES 



spraying the pear foliage with bordeaux mixture 4-5-50 or 

 lime-sulfur solution 1-50 will satisfactorily control Myco- 

 sphserella leaf-spot. Three applications are sufficient in the 

 orchard; (1) just after the petals fall; (2) two weeks later; 

 (3) two weeks after the second application. In the nursery 

 it is recommended that two-year-old budded pears be sprayed 

 shortly after the new leaves open. Subsequent sprayings 

 should be made at two-week intervals; three sprayings in 

 all will prove profitable for two-year-old budded stock. But 

 since one-year-old budded stock is rarely attacked to a damag- 

 ing extent, it is regarded as unprofitable to spray such trees for 

 this disease. 



REFERENCES 



Stewart, V. B. Some important leaf diseases of nursery stock. 

 Septoria leaf-spot of the pear. Cornell Univ. Agr. Exp. Sta. Bui. 

 358 : 216-219. 1915. 



Duggar, B. M. Some important pear diseases. I. Leaf spot. Cor- 

 nell Univ. Agr. Exp. Sta. Bui. 145 : 597-611. 1898. 



Barrus, M. F, Diseases of pears. Leaf spot. In The Fruit Industry 

 in New York State. New York Agr. Dept. Bui. 79 : 1049-1050. 

 1916. 



SUPEKFICIAL BARK-CANKER 



Caused by Myxosporium corticolum Edg. 



A roughening of the bark of both pears and apples is exceed- 

 ingly common in eastern United States. (See Apple, page 

 130.) 



FROST-INJURY 

 Caused by the action of low temperatures 



At times pear trees are severely damaged by frost. The 

 trees are often planted on low, rich soil, and from their loca- 

 tion are more subject to cold. A difference in elevation of 



