110 MANUAL OF FRUIT DISEASES 
point of union with the root. Mature galls may measure from 
one to several inches in diameter, are dark in color, with a 
roughened surface, and 
usually hard. Young 
galls are comparatively 
small, greenish, or some- 
times slightly flesh- 
colored, relatively smooth, 
and soft or even spongy. 
The second form of the 
disease, hairy-root, is 
quite unlike the gall form 
just described. As the 
name suggests there is an 
excessive production of 
small fibrous roots, which 
give to the system a hairy 
appearance (Fig. 31). 
These may be grouped 
into several types, as 
follows : (a) a simple type, 
in which numerous small 
roots grow out at nearly 
right angles single or in 
tufts from an older root 
or stem; (b) a woolly 
form which originates 
from a smooth irregular 
swelling usually on the 
larger roots near the sur- 
Fic. 31. — Hairy-root of apple. face of the soil; (¢) a 
broom-like formation in 
which there is excessive branching of the roots at the ends. 
Both the crown-gall and hairy-root forms of the disease 
