1 8 How TO MAKE GRAPE CULTURE PROFITABLE IN CALIFORNIA 



part of summer. It is needless to say that the vines at grafting 

 must be perfectly healthy. 



Cutting down vines about an inch below the surface during 

 winter also has a salutary effect. It may be better in California 

 to do this towards spring, as the bleeding of the vines keeps back 

 the growth till the excess of moisture has disappeared from the soil. 

 This work should also be done in large tracts, as the moisture can 

 be held more uniformly in the ground than if done in small blocks. 

 It may also be that late pruning has a beneficial effect in this re- 

 spect as it decreases the vigor of the vines somewhat. 



8. Method. Irrigation. 



This is probably the best preventive of any, if properly applied, 

 but as it is generally practiced, i. e., filling up the ground with water 

 in the spring, when it is too wet already, it is apt to make matters 

 worse. Vines should not be irrigated, barring exceptional cases 

 irom this statement, till about two weeks after the bloom. As 

 irrigation during the summer creates shallow root-growth, this 

 must be kept alive and healthy by a repetition of the practice, at 

 least on heavy soils in some localities. Shallow root-growth can be 

 prevented by plowing deep furrows to let the water down into 

 the ^ubsoil and so avoid moistening of the surface. Care should 

 be takers not to cut any of the main roots during the summer, as 

 this would be apt to weaken the vine. It is self-evident that the 

 furrows should be well filled up with loose, dry soil, after the 

 ground is dry enough to do this properly. The water should al- 

 ways be applied in the same places. Young vines should not be 

 irrigated, unless it is impossible, as may be the case in some in- 

 terior localities, to keep them in healthy growing condition without 

 : t. In such cases it should be done early and not late. 



The cause of the trouble may also be explained thus : The 

 climatic and soil conditions of California being both very favorable 

 during the forepart of the season, cause the vine to make excessive 

 and soft growth in root and top ; while the climatic conditions re- 

 main the same, the soil condition becomes very adverse later on. 

 So a good way to strengthen vines again, which are weak already in 

 this respect, would be to hold only a fair amount of moisture in the 

 soil with spring cultivation and then irrigate heavily and frequent- 

 ly later in the season, where this can be done. For reasons ob- 

 vious from the above young vines are seldom attacked, even if the 

 cuttings used for their propagation were taken from vines, in which 

 a predisposition to the disease was already strongly developed, be- 

 cause they have plenty of moisture during the latter part of the sea- 

 son, as they do not make sufficient growth to exhaust the moisture 

 supply. 



All these preventive methods are given with regard to Vini- 

 feras on their own roots. Whether these, excepting proper irriga- 

 tion, would be of much avail for vines grafted on Rupestris, which 

 has a much weaker adaptation in this respect than the Vinifera 

 root has, I cannot tell. 



Resume: In order to prevent the disease, be very careful in 



