Causes. These facts seem to indicate that we can ascribe the failure 

 of the vines to a general cause acting over the whole district; a cause, 

 however, which was only effective where supplemented by one or more 

 contributory conditions. These conditions are: 



1. Excessively gravelly soil. 



2. Susceptibility of the variety of vine, due probably to heavy bearing 

 and perhaps to some peculiarity of wood and foliage, or roots. 



3. Large wounds made in pruning. 



4. Age of the vine. 



5. Severe cutting back of the young growth by spring frosts. 



The general cause seems to be the combined effect of the heavy crops of 

 1896 and 1897 and the four years of drought which followed. 



Rainfall and Crops. The following statistical table, made up from 

 data furnished by the Weather Bureau and by two of the largest vine- 

 growers in the most seriously affected districts, fortifies the above 

 position : 



Relation of Precipitation and Irrigation to Crop, in Vineyards in Santa Clara Valley. 



a Irrigated 35 acres. 



> Irrigated 300 acres. 



c Irrigated 70 acres in February. From 50 acres of the irrigated land were obtained 

 49 tons of grapes, and from the remainder of the vineyard only 45 tons. This indicates 

 about 1 ton per acre on the irrigated and about % ton per acre on the unirrigated 

 portion. 



d Estimated from the wine produced. 



If the figures given for these two vineyards are typical, which there 

 is every reason to suppose, they may help us to find a sufficient cause 

 for the death of the vines without taking refuge behind the mysterious 

 and highly unsatisfactory Anaheim disease. In 1896 the vines bore a 

 large crop, but were supplied with sufficient water by a rainfall of three 

 inches above the normal. They therefore entered the season of 1897 

 healthy, but probably not with an excess of reserve food-material laid 

 up in the stems and roots; for the weakening effect which a heavy crop 



