12 UNIVERSITY OP CALIFORNIA. 



Time Required to kill Phylloxera in a vineyard by Submersion in Water. 



From the table it will be seen that, with the necessity of Continuous 

 submersion from 1 to 2 feet, the operation is not so simple as many sup- 

 pose. It will not do to leave too much of the trunk of the vine or canes 

 exposed above the water-level. Hence it is that in the case of high- 

 pruned vines the depth of the water must be greater than in the case 

 of short-pruned vines. The duration of the submersion depends, to a 

 certain extent, upon the climate. In very cold countries the duration of 

 the complete submersion may be considerably shortened. The table is 

 given for warm or temperate climates, such as that of California. 



Dangers of Submersion. It is to be remarked that submerged vines 

 speedily perish from " black knot." "gouty swellings," etc.; besides such 

 vines are extremely sensitive to the attacks of the "powdery mildew" 

 and other fungous diseases. It may be added that heavier fertilization 

 is required on vineyards that are submerged than otherwise would be 

 the case. 



PLANTING IN SAND. 



In this case, too, it is to be noted that a merely "sandy soil," as is 

 generally understood by the term in this State, is not sufficient to check 

 the spread or development of the phylloxera. There must be at least 

 85% of pure sand in a soil that is to be relied on as a phylloxera- 

 proof soil. But even this high percentage of sand is not sufficient, if 

 there be a slight admixture of clay. More or less lime does not make 

 much difference. It has been found that while the Vitis Vinifera will 

 grow well in sandy soils of the above description, yet they require heavy 

 fertilization and yield crops of an inferior quality, though heavy 

 quantity. 



RESISTANT VINES. 



It being, then, not economical, except in very special cases, to attempt 

 to destroy the phylloxera itself, we are inevitably driven to the con- 

 clusion that all of our vineyards on non-resistant roots will sooner or 

 later perish under the attacks of the insect. We can, however, replant 

 the vineyard on roots that, while tolerating the insect, suffer nothing or 

 little from its bites. This is the only reliable measure thus far found to 

 be of practical value to those who would grow grapes. While it involves 

 the loss of capital expended in a growing vineyard, it enables us for 

 the future to guard against further loss from the same cause; and, in the 

 case of new plantations, it shuts out the occurrence of the loss. 



Replanting of European Vines. It is mere folly to plant the Vitis 

 Vinifera, on its own roots, in vineyards where the phylloxera has already 

 destroyed the vines. While it is possible for a full-grown, healthy 



