PREVENTIVE METHODS OF CALIFORNIA VINE DISEASES 9 



CHAPTER II. 



Preventive Methods of California Vine Diseases. 

 1. Method. Selection of Proper Resistant Grafting-Stocks. 



There are four requirements with which good resistant stocks 

 should comply : 1. Resistance to California vine disease or greatest 

 possible range of adaptation to the changes from wet to dry in the 

 soil; 2. Resistance to Phylloxera; 3. Adaptation to other climatic 

 and soil conditions; 4. Affinity and good general behavior after 

 grafting to Viniferas. 



In order to overcome the weakness of the Vinifera top and as 

 any slight injury to the roots of a vine or tree may cause overbear- 

 ing, an augmenting factor to the disease, it is plain, that only graft- 

 ing stocks possessing the highest resistance against the Phylloxera 

 as well as the greatest flexibility of adaptation both to wet and dry 

 conditions of the soil, are perfectly safe. A resistance-coefficient of 

 16 is generally considered high enough for any soil, as it makes the 

 vine safe against any injury to its roots by the Phylloxera. This 

 does not say that a higher one is not preferable, providing the other 

 qualities of the stock in question are as good. I have been under the 

 impression for some time, that vines with thick fleshy roots are the 

 best for California conditions. Of two vines, having the same adapt- 

 ability, the one with the thickest roots will be the most dryness-en- 

 during. For this reason the Solonis, which has small roots but a 

 great adaptation to short changes from wet to dry and vice versa ; 

 as is attested to by French experience and that of Mr. T. V. Mun- 

 son, does not last at all during our long, dry summers. 



It does not matter materially, whether the main roots extend 

 themselves horizontally and the laterals run down deeply, or the 

 main roots approach a vertical direction. I believe, for rich, level 

 and irrigated lands I should prefer the former, as I think they will 

 give better results, and for loose gravelly soils the latter. In such 

 soils the moisture cannot rise to the surface by capillary attractions, 

 but settles down by gravity; the usefulness of a vine with very deep 

 vertical main roots is therefore apparent 



New vines intended for stocks can be tested in the following 

 manner: On a piece of level, clayey ground, either shallow or of 

 an even texture to a great depth, some of the vines should be planted 

 along with some Lenoir, Vinifera- and Riparia-Berlandieri for com- 

 parison. They should be either rooted cutting-grafts, or if ungraft- 

 ed should receive a Vinifera top as soon as large enough for graft- 

 ing, as testing stocks with their own tops would be of no importance, 

 because they act quite differently after being grafted. In order to 

 accelerate the testing it is best to. plant the vines rather close, about 

 six feet each way. The plot should be well cultivated the first two 

 years in order to enable the vines to get a quick start. The third 

 year the ground should also be well cultivated up to the last rain ; 

 after that it should not be stirred any more, in order to let a crust 

 form on the surface. During June it should be irrigated about once 

 a week, to soak it up well with water and the irrigating furrows left 



