DISEASES OF SPECIAL CROPS 



Pacific coast canker, black-spot canker ' (Macrophoma 

 curvispora Peck) . — The Pacific coast canker is particu- 

 larly destructive in the northwestern states west of the 

 Cascade Moun- 

 tains. It was first 

 noted about 1893 

 when it developed 

 in such destruc- 

 tive form as to 

 cause the Wash- 

 ington State 

 Board of Horti- 

 culture to call 

 upon the Federal 

 Government for 

 its investiga- 

 tion. It has since 

 been reported in 

 Oregon, Idaho, 

 Nebraska, and 

 British Columbia. 



The bark or sap- 

 wood of twigs and 

 larger branches is 

 the seat of infec- 

 tion, but the dis- 

 ease may occur 



also upon the fruit when in storage. The loss of an entire 

 orchard within a few years has resulted from the black- 

 spot canker. Young trees, owing to their tender bark, are 

 especially susceptible. 



1 Lawrence, W. H., Wash. Agr. Exp. Sta. Bui.' 66, p. 5, 1904. 



Fia. 30. — Black spot canker (macrophomose). 

 Cordley. 



After 



