416 MANUAL OF FRUIT DISEASES 
ARMILLARIA Root-RotT 
Caused by Armillaria mellea (Fries) Quel. 
Raspberries are seriously injured by the shoe-string fungus 
in the Pacific Northwest. (See fuller account under Apple, 
page 96.) 
BLUE-STEM 
Caused by Acrostolagmus caulophagus Lawrence 
This is a raspberry and blackberry disease peculiar to the 
Pacific Northwest. It has been increasingly troublesome in 
the Puget Sound region since 1904. All blackcap varieties of 
raspberries are susceptible. It also affects red raspberries. 
Symptoms. 
In general, when raspberries are affected with blue-stem the 
plants fail to mature the crop properly and they may die during 
the summer. The canes usually are first to show signs of the 
disease. The fruit begins to dry up and harden before maturity. 
This change in the fruit is accompanied by a discoloration and 
wilting of the leaves and a darkening of the canes. Symptoms 
vary with the severity of the attack. 
The first discoloration of the shoots occurs a few inches 
above the ground. A blue-black stripe extends from some point 
a few inches above the ground upwards on the shoot. The 
stripe may be narrow, or the whole side of the shoot may be 
dark-blue. Very commonly shoots are discolored throughout 
their circumference for three feet from the ground. This dis- 
coloration may increase three to six inches in length each day 
during the growing season. At the ends the dark-blue area is 
fringed and fades into a reddish brown color. The margin is 
quite distinct. As a result of this affectation some shoots may 
die. Death occurs throughout the entire growing season, al- 
