14 
The Colorado Experiment Station 
The infection at the node can be traced, in nearly every case, to 
a lesion on the petiole which has spread toward its base and involved 
the bud region. From the nodes, the discoloration spreads rather 
rapidly into the inter-nodes, the discoloration from one coalescing 
with that from another, sometimes entirely encircling the cane, so 
that in six weeks time the whole bottom third may be dark, purplish 
brown in color. Fig. 5 shows a portion of two such canes on the 
left, and a healthy one on the right. In Fig. 6, four diseased 
(left) and three normal (right) canes are given to illustrate the 
distribution and extent of the discolored areas late in the season. 
(Sept. 13, 1913.) 
The bark or cortex frequently cracks and splits for a distance 
longitudinally, where it has become brown and exposes the moist, 
green tissue beneath. (Fig. 4 colored plate.) As a result of this, 
the canes dry out prematurely, become brittle and break very easily, 
when they are put down in the fall and taken up in the spring. 
This fact coincides with the statement of the growers that the canes 
have become more brittle in recent years than formerly. Whereas 
less than 5 per cent, should be lost in this way, some growers esti¬ 
mate the number as large as 30 to 50 per cent.; some report only 2 
per cent, broken, while the average is between 10 and 20 per cent. 
From the middle of September to the first of October, grayish 
white patches may be seen developing in the center of the brown 
blotches (Fig. 7), and if these light areas are examined very care¬ 
fully a few weeks later, they will be found to be thickly studded 
with minute black specks or pustules. (Fig. 8.) 
Pathological Changes. 
A microscopic examination of a cross-section of a raspberry 
cane discloses three rather well defined cortical regions beneath the 
epidermal layer. The outer one consists of relatively large thick- 
walled cells along the outer edge, the middle one of large thin- 
walled cells, and the inside one of smaller thick-walled cells. By 
exercising special care, it is possible to separate the outside struc¬ 
ture from the inside with a sharp scalpel, owing to the fragile char¬ 
acter of the large thin-walled cells of the middle region. If the 
outside portion is removed from a healthy, green cane free from 
all discoloration, the aspect of the remaining inside region is almost 
white with a faint suggestion of green. If a similar dissection is 
made of a brown diseased cane thru the brown spot, both the out¬ 
side and inside portions of the cortex will be found to be brown in 
color. Such a dissection is shown in Fig. 9. Here the outside 
part was peeled from adjoining normal and diseases areas and 
