The Anthracnose Disease of the Raspberry 



163 



been observed on the black raspberry, was first noticed by Stewart, Rolfs, 

 and Hall (1900). 



As a rule the lateral branches are less severely affected than the principal 

 canes. Occasionally young laterals are killed when they first develop. 

 These branches become dry and the tissue is hard and brittle, while scab- 

 like lesions entirely girdle the base and extend up the young shoot. The 

 lateral shoots that arise from two-years-old canes and bear the fruit, 

 however, are never seriously diseased. Although spots often occur on 

 them the lesions are small and cause comparatively little injury. 



ON petioles and pedicels 



Anthracnose is not found commonly on the petioles and the pedicels 

 of the raspberry. When it does occur there the spots are similar to those 

 on the canes, although frequently the purple margins are absent and the 

 afi^ected area is pale buff, raised and scablike. The diseased petioles 

 and pedicels become brittle, while the fruit is retarded in its maturation 

 in proportion to the severity of' the infection. 



ON the leaves 



The disease appears on the leaves of the raspberry somewhat later in 

 the season than on the canes. Small purple spots with light-colored centers 

 may appear scattered irregularly over the upper surface of the leaf, or 

 they may be found in rows where the leaf is creased or folded (fig. 14). 



Fig. 14. ANTHRACNOSE DISEASE ON THE LEAVES OF RASPBERRY 



The spots occur in rows, but not necessarily on the veins 



18 



VI 



