166 MANUAL OF FRUIT DISEASES 
Reimer, F. C., and Detjen, L. R. Double blossom of the dewberry 
and the blackberry. North Carolina Agr. Exp. Sta. Ann. Rept. 
34:41-50. 1912. 
Cook, M. T. Some diseases of nursery stock. Double blossom of the 
dewberry. New Jersey Agr. Exp. Sta. Cire. 35:24. 1914. 
ARMILLARIA Root-Rot 
Caused by Armillaria mellea (Fries) Quel. 
The shoe-string fungus attacks the blackberry among other 
plants. It is said that considerable injury is done in the Pacific 
Northwest. (See Apple, page 96.) 
LEAF-SPOT 
Caused by Septoria Rubi Westd. 
The common leaf-spot of blackberry affects also the rasp- 
berry and dewberry. It is found in almost every locality where 
these fruits are grown. While the disease is common, it is not 
often serious. Rather it is enphytotic, doing but little damage 
under ordinary conditions. In 1905, however, 20 per cent 
foliage-losses were reported, from Ohio and Florida. 
Symptoms. 
The appearance of this disease is said to vary to a marked 
extent on different varieties. On some varieties the spots on 
the leaves (Fig. 46) are light-brown, while on others they are 
dark-brown. The lesions are comparatively small, measuring 
about one-eighth of an inch in diameter. The diseased portion 
is at first purplish, although a brown color is assumed as the 
affected tissue dies. In old spots the center is whitish, and the 
border is brownish or reddish. 
Cause. 
The causal fungus is Septoria Rubi. It belongs to a group of 
organisms the life-histories of which are fairly well understood. 
