24 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



and finer the graft the greater the difficulty the Lenoir has in supply- 

 ing it with its full quota of nutriment. 



But if the rootlets of the Lenoir are much damaged by the Phylloxera, 

 the equilibrium can not be maintained and the graft will show signs of 

 distress. Why, then, have the vines at the East Sonoma experiment 

 plot lived so long ? The answer to this question is, that the vines were 

 formerly short-pruned and were unproductive, but that since 1902 they 

 have been long-pruned and made to produce largely. 



In the first case the equilibrium between the stock and the graft was 

 practically maintained; in the latter, it was destroyed. It must not be 

 forgotten, however, that the Phylloxera is in a measure an active agent 

 in causing the Grape-shrivel, and that the severity of the disease during 

 1903 and 1904 may be due to circumstances favoring the development 

 of this pest. 



In combatting the Grape-shrivel on grafted vines, two things must be 

 taken into account: First, the affinity between the stock and the graft; 

 second, the resistance of the stock to the Phylloxera. 



The affinity (and by affinity we mean all the necessaries to a con- 

 joint life) between stock and scion is to be maintained in equilibrium 

 by judicious pruning, supplemented by thorough fertilization. 



The resistance of the stock to the Phylloxera will be indirectly 

 heightened by fertilization; but if then found to be insufficient, it 

 should be changed for a more resistant one. The use of bisulfid 

 of carbon, in protecting stocks of low resistance from the attacks of 

 Phylloxera, is not at present an economic possibility. 



ROOT-ROT.* 



The action of this disease in its main characteristics is very similar 

 to the malady known among the French as the Pourridie, or Blanc des 

 racines, and in Germany, according to Mr. P. Viala,f by the name of 

 Weinstock-faule. The areas of depressed vegetation that one associates 

 familiarly with the action of the Phylloxera, are characteristic also of 

 the Root-rot. In each case there is a center of infection, though, when 

 compared with the Phylloxera, the Root-rot spreads more slowly and 

 appears circumscribed or local in its action. In the case of the Root- 

 rot there may occur many small centers of infection in close proximity 

 to one another which may take several years to merge into one; whereas, 

 in the case of the Phylloxera, when infection is so general that several 

 centers start very near one another, they rapidly become one. 



* These remarks of Mr. Butler on the Root-rot are of very great importance at the 

 present time, as this disease is doing a great deal of damage in certain parts of Santa 

 Clara, Sacramento, and San Joaquin valleys. In some districts the Root-rot is far more 

 destructive than the Phylloxera. <(E. H. T.) 



t P. Viala: "Les Maladies de la Vigne," 3d ed., page 248. 



