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- 



FIG. 31. Hairy-root of apple. face of tne soil '> M 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 



