24 UNIVERSITY OF CALIFORNIA. 



will develop vigorously in compact soils, as they have a powerful root- 

 system. Years of experiment have established this fact beyond the 

 possibility of dispute. 



Humidity. The humidity of the soil exercises considerable influence 

 upon the vegetation of the vine. An excess of humidity is very favor- 

 able for the development of fungous diseases, coulure, etc.; besides this, 

 it checks the proper development of the root-system. Plants growing 

 in a very moist soil frequently seem to give a more luxurious external 

 vegetation than those growing on drier soils. In such cases the root- 

 system is always more feeble than would have been the case had the soil 

 been less moist. This phenomenon is not peculiar to the vine, but is 

 observed with all plants. The root-system is always more developed in 

 dry soils (without excess, of course), because of the vine being forced to 

 seek moisture at a greater depth. It would seem, therefore, that in dry 

 soils such as may be said to be characteristic in the majority of Califor- 

 nia vineyards, the root-system must be very well developed, as its 

 enfeeblement counts heavily against the plant. It is, therefore, apparent 

 that on the dry soils of this State vines should be planted whose resist- 

 ance to the phylloxera is above the average. This consideration is 

 independent of other complicating considerations. For dry, gravelly, 

 or sandy soils only such species must be chosen as give a high resisting 

 power and well-developed root-systems. 



An excess of water in the soil presents another difficulty. Young 

 vines planted under such conditions will scarcely root at all, and though 

 they may give at first seemingly a good top-growth, yet when dry 

 weather comes they generally perish or suffer to such an extent that it 

 is impossible to get from them normal results. 



Humidity acts frequently in conjunction with compactness, as it does 

 with coldness, of the soil. The latter, however, generally is the result 

 of the two former. This combination of compactness, humidity, and 

 coldness of the soil will delay the starting of the growth in spring, and 

 thus injure the timely nourishment power of the vine. 



Fertility. Fertility is a powerful adjunct of the proper vegetation of 

 all plants; the more fertile a soil is, the better will be the vegetation 

 thereon. However, very great fertility of the soil is not necessary for 

 all kinds of American vines. The Rupestris is, perhaps, the species 

 which thrives the best in poor soils, especially if tending to dryness. It 

 attains considerable dimensions and supports the graft very well under 

 conditions in which other vines would scarcely grow at all. The Riparia 

 is far more exacting in this respect. The Lenoir and Herbemont 

 accommodate themselves very well to poor soils. 



Such are the principal conditions which influence the vegetation and 

 development of the vine in the generality of soils, such as are to be dealt 

 with in this State. As has been said, it will not be profitable to compli- 

 cate the study of the adaptation of resistants in this State at the present 

 time, with the numberless exceptions that arise when one has to deal 

 with soils in which there is a large excess of lime. There are few such 

 soils in the viticultural regions, so the consideration of these complica- 

 tions will be deferred to a more profitable time. 



The general considerations given above are, of course, easily modified 

 to suit particular cases. Lightness of the soil and, in consequence, permea- 



