OBSERVATIONS ON SOME VINE DISEASES IN SONOMA COUNTY. 25 



The Root-rot is caused by a fungus, possibly several, fungi, and in 

 its usual form is very easily recognized upon digging up any vine 

 within an infected area. The roots are soft, watery, yellowish-brown 

 in the entire woody cylinder, and more or less permeated with whitish 

 threads the mycelium of the parasite and give off a strong nauseous 

 fungous odor. As the lower roots are destroyed, and the mortification 

 enters the body of the vine and slowly eats its way in the trunk to the 

 surface of the soil, and even above, new roots are sent out from the still 

 healthy encompassing tissue; these roots, in turn, become riddled with, 

 and succumb to the attacks of the fungus. In the last stages of the 

 disease (that is, when the vine has sent out a few feeble canes about a 

 foot long) one invariably finds near or at the surface of the soil, a very 

 free growth of young tender roots. 



Though the Root-rot is generally of the form just described, and takes 

 from two to five years to kill the vine, it may, in some rare cases and in 

 young vineyards, spread with such rapidity that it kills the vines in 

 eighteen months, and even in a single season. Mr. P. Viala observes: 

 "The vines may succumb in from fifteen to eighteen months," and that 

 he "has even caused their death in six months by placing them under 

 the most favorable conditions for the development of the Pourridie." * 



The author observed, during the summer of 1904, in a young vine- 

 yard, a remarkably intense and destructive attack of Root-rot, which, in 

 many instances, had gained an entrance into the vines during the late 

 spring or early summer, and had practically ruined the greater part of 

 them by October. Many there were that would not "come out" in the 

 spring, or, if they did, would die during the summer. 



The growth of vines affected with the usual form of Root-rot resembles 

 that of vines affected with the Phylloxera. Their growth gradually 

 becomes weaker and weaker, and the vines finally die. But in the rapid 

 form of this disease there is no such gradual wasting away. The foliage 

 of the vines becomes chlorotic, and, if the weather is at all unfavorable, 

 rapidly sears and falls off. The blade of the leaf not infrequently sep- 

 arates from the petiole, which remains a while longer attached to the 

 shoots. The maturity of the shoots is impeded; their lignification is 

 imperfect, irregular, and at times resembles that which has come to be 

 considered typical of the Anaheim disease; in other words, strips on 

 elongate spots of immature tissue may be found in the midst of mature 

 wood. The fruit matures imperfectly. The photograph of the vine 

 shown in Fig. 5 was taken early in October, and shows the general appear- 

 ance of a young vine affected with the rapid form of the Root-rot. The 

 vine was evidently not affected with this disease, if we may judge from 

 its growth, until late in spring. 



The appearance of the diseased vines below ground is necessarily 

 different from that of those affected with the milder form of the Root- 

 *P. Viala: "Monographic du Pourridie," Introduction. 



