Mar. 6, 1917 
Little-Leaf of the Vine 
39 1 , 
The flattening, or ratio between the longest and shortest diameters of 
the canes, is marked in some cases. Measurements made showed this 
ratio to average 1.22 in healthy vines and 1.38 in corresponding diseased 
vines. 
ARMS 
On the 2-year-old wood, from which the canes arise, the flattening is 
even more common and pronounced. The arms on badly diseased vines 
are shorter and less numerous than on healthy vines. This is due to the 
dying back of the second- and third-year-old wood and the removal of the 
arms in pruning. The water sprouts from old wood being usually larger 
and more vigorous than the fruit canes on younger wood, the pruner has a 
tendency to utilize them for spurs. This tends to keep the arms short. 
A section through the 2-year-old part of an arm shows yellowish points 
usually confined to the 2-year-old wood. Sometimes these points are 
so numerous as to color the whole surface of the section and then a few 
points may occur on the 1-year-old wood. These yellow points occur 
also on apparently healthy arms, but rarely and never abundantly. 
Sections made successively through older parts of the arm show more 
numerous and darker points. In wood 4 to 6 years old these points are 
nearly black. They are usually scattered through all annual growth 
rings except that of the current year. 
The microscope reveals in these dark and yellowish spots the presence 
of thyloses and gum in the xylem tubes, parenchymatous cells and in a 
few xylem fibers adjoining them (PI. 90, A; 91 , A, B). The medullary 
rays close to affected tissues show dark cells filled with a granular and 
brown substance unstained by iodin. 
TRUNK 
Dark points like those in the arms are also found in the trunk. 
They can be followed almost to the base of the underground stem. At 
the head of the vine, where the arms start, occur the most abundant dis¬ 
eased areas. These gradually diminish in number as we approach the 
base of the underground stem. This progressive diminution is shown 
in Plate 91, C-E. This represents three sections through the trunk of 
a badly affected 3-year-old Petite Sirah vine. Figure C is a section at 
the branching point of the arms about 12 inches above the surface of the 
ground. The wood of the first two years is all of a uniform yellowish 
brown color. D is a section at the level of the ground. It shows 19 
# dark dots or small patches distributed through 2- and 3-year-old wood. 
E was made at 6 inches below the surface and shows only 9 of these dots. 
Only 3 dots were found in a section made at the base of the underground 
stem. 
Microscopically, these diseased areas show the same gummy matters 
noted in other parts, but they are darker. When the tissues are stained 
78365°—17 - 3 
