OBSERVATIONS ON SOME VINE . DISEASES IN SONOMA COUNTY. 29 



ing them treated with a three per cent solution of blue vitriol* or a 

 seven per cent solution of green vitriol. f This is done by digging with 

 a hoe a small basin around the trunk of the vines and pouring into it a 

 gallon or so of either solution, the quantity being determined by the 

 nature of the soil and the supposed extent of the root-system. If for 

 any reason it is inconvenient to treat the vines with either of the vitriol 

 solutions, a pound of either the bluestone or the copperas may be placed 

 around the trunks and allowed to dissolve in the winter rains; but this 

 method will not be as effective. Before replanting the areas destroyed 

 by the rot, the holes destined to receive the young vines should be 

 partly filled with either blue or green vitriol solution, and then, when 

 the fungicide has soaked away, planted. In soils that are subject to 

 the Root-rot, rooted vines should always be planted, and as shallowly 

 as cultivation will permit. Cuttings should never be used, for they have 

 to be planted deeper than rooted vines, the chances of infection, 

 especially on the cut surface, being thereby increased. 



Vineyards that have once been infected with the Root-rot are, unless 

 drained, always subject to it; therefore, it is essential that those parts 

 that have been destroyed by this disease should, when replanted, be 

 treated every two or three years by one of the methods above outlined. 



The Root-rot attacks not only the common grapevine ( Vitis vinifera), 

 but probably also more or less severely the different resistant stocks. 

 The Rupestris St. "George is very sensitive to it; but according to Mr. 

 Jallabert,J whose demonstration is quite convincing, the Riparia X 

 Rupestris 3306 is almost immune. He planted the latter in a soil 

 infected with the Pourridie and which, even in the dog days, could only 

 be worked to a depth of six inches. "Somewhat below this the clay 

 was saturated, and, lower down, mud." In such a soil as this, and 

 despite the Pourridie, the 3306 flourished. We may feel confident, then, 

 that wherever the Root-rot is bad in California, the Riparia X Rupes- 

 tris 3306 will more than hold its own. 



*J. Dufour in "Chronique Agricole du Canton de Vaud," quoted by G. Foex, 

 " Cours Complet de Viticulture," 4th ed., page 603. 



t J. Bonjour: " Manuel Pratique du Vigneron," page 71. 



\ J. Jallabert: " Resistance du Rupestris du Lotet du Riparia X Rupestris 3306 au 

 Pourridie," Revue de Viticulture, tome XI, page 92. 



Loc. cit., page 5)4 et suiv. 



