DESCRIPTION OF THE FORMS OF CROWN-GALL. 11 



the crown-gall and a great variation of susceptibility is shown by 

 European varieties. 



In Cape Colony, as well as in the United States, certain varieties 

 are subject to the crown-gall, such as the Muscat of Alexandria 

 (Hanepoot). Mr. C. P. Lounsbury reports, by letter, that as much 

 as 70 per cent was found diseased in a vineyard six or seven years 

 old planted with Hanepoot (Muscat of Alexandria) vines. In vine- 

 yards in Texas, New Mexico, and Arizona all the vines of this variety 

 and of the Mission variety are often diseased, and many of them 

 are dead at the end of four years. In one vineyard at Bernalillo, 

 N. Mex., 3,000 Mission vines died from the disease in four years 

 from the time the vineyard was planted. The loss from the ravages 

 of the disease is a large and important item in many localities, 

 especially in this section, amounting to many thousands of vines. 



If we consider the northern form of disease known as necrosis (41) 

 or black-knot (22) as identical with crown-gall, the importance of 

 the disease is greatly increased. Until it has been definitely proved 

 that this form of disease is due to a different organism, owing to 

 the apparent similarity of the black-knot of the Northern States 

 and the cane-gall form of crown-gall in the Southwestern States, 

 the writer will consider these forms of disease identical. 



DESCRIPTION OF THE FORMS OF CROWN-GALL. 



ROOT GALLS. 



The disease is most frequently found in its earlier stages in the 

 form of more or less spherical, fleshy galls, or outgrowths (PI. Ill, 

 fig. 2), from the roots of young plants grown from cuttings or at 

 the point of union of scion and root in young grafted vines. These 

 usually originate in a wound. They often become confluent (PI. II, 

 %. 1). 



These galls at first are white or flesh colored and can not be dis- 

 tinguished from callus, but they usually develop more rapidly. 

 The surface as they grow older is more or less coarsely convoluted. 

 They more frequently occur near the surface of the ground and 

 often attain a diameter of 2 or 3 inches on large vines. 



CANE GALLS. 



The disease on old vines extends from the crown upward and 

 attacks the older branches of the canes, often to the height of from 

 3 to 5 feet from the ground. Fleshy excrescences or confluent galls 

 develop usually along lines parallel to the length of the canes (PI. 

 II, fig. 2). These growths are sometimes continuous for several 

 inches or may develop in bunches. In spring the young galls resemble 



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