OBSERVATIONS ON SOME VINE DISEASES IN SONOMA COUNTY. 27 



one's attention. But when one examines a diseased vine a little more 

 closely he discovers that it gives off the nauseous fungous odor so 

 characteristic of the Root-rot, and that a cross-section through the 

 stem or roots shows, between the wood and the bark, a dirty white sub- 

 continuous line, which is not very distinct and is easily overlooked. 

 If, however, a piece of the bark is cut off, there will appear between it 

 and the woody cylinder a white, or grayish felt-like, mass of interwoven 

 threads the mycelium of the Root-rot fungus. The vine shown in 

 Fig. 5 was one mass of this fungous growth to within an inch or so of 

 the surface of the soil. 



The vineyard in which the exceptionally severe form of Root-rot just 

 described was observed had been established in 1902, on land that had 

 been cleared during the year 1900. The piece of land on which the 

 vineyard is planted lies on the sunny slope of a fairly steep range of 

 hills. This slope in profile might be likened to an S reversed and con- 

 siderably drawn out lengthwise, and lying at an angle of about thirty 

 degrees with the horizontal. The soils in this piece of land are both 

 poor and good. Beginning at the bottom, and extending up the slope 

 some one hundred feet, we find a very shallow sandy soil, inclined to be 

 compact and hard, and underlaid, at a depth of a foot or more, with a 

 clayey subsoil. This soil becomes very wet in winter. On the remain- 

 der of the slope the soil is friable, inclined to red, fertile, and with the 

 subsoil considerably below the surface. In this soil the vines may be 

 completely dug out with a spade, whereas a mattock, and a good one, is 

 needed to remove the vines from the soil at the bottom of the hill. The 

 growth of oaks, before the land was cleared, was meager at the bottom 

 of the slope, on the refractory soil, but quite dense everywhere else. A 

 year after the land was cleared the vines were planted. They were 

 Carignanes grafted on resistant stocks. On the light, friable soil the 

 Rupestris St. George was the stock employed; whereas on the refractory 

 soil at the bottom of the hill, Rupestris of the Fort Worth type appears 

 to have been exclusively used. The former were more vigorous than 

 the latter. 



These being the facts one would naturally expect the Root-rot to 

 develop first among the Fort Worth Rupestris, and spread from these 

 to the Rupestris St. George. This would certainly have been more in 

 accord with the general behavior of Root-rot fungi. The reverse was 

 true, however; the Rupestris St. George and not the Fort Worth 

 Rupestris were the vines affected. 



But with the Root-rots, like with many other parasites of both the 

 vegetable and animal kingdoms, the usual areas of adaptability, when 

 one or more conditions are particularly favorable, may be passed over. 

 In fact, it is well known that in the case of the Root-rot, though 

 usually serious only in wet soils, it may spread in comparatively dry 



