156 



DISEASES OF ECONOMIC PLANTS 



high-bush blackberry. It is most abundant on the 

 Lucretias, but is also a serious pest on the Rathbone. 

 The disease makes its appearance in the spring, just as 



Fia. 



07. — The Dewberry double blossom showing witches' broom of the vino. 

 After Cook. 



the leaf buds are opening, although it can be detected 

 previous to that time by the enlargement of the diseased 

 buds. 



Instead of the normal shoots and leaves a witches' broom 

 is produced ; the entire bud being involved or only a part, 

 according to the attack. When the flower buds open, they 



