WINE-MAKING IN CALIFORNIA. 199 



ensues, by which the sap vessels below are extended to burst- 

 ing, the sap vitiates, and in oozing out through the bark, 

 forms these abnormal warty excrescences. Vines grown from 

 cuttings of very large, porous wood are also more subject to it 

 than those from medium, firm, short -jointed wood. I have 

 already referred to injudicious short pruning, reducing a vine 

 of say 300 buds, to eight or ten, as one, and the most preva- 

 lent, cause of black knot. Judicious pruning, and in case of 

 very destructive frosts in Fall or Spring, or the breaking of the 

 vine as may sometimes happen, grafting may prove a preven- 

 tative, as the scions will then serve as conductors and eleva- 

 tors of the superfluous sap. In resorting to this remedy in 

 large vines, it will be well to take them low down, and leave 

 several buds to the scions. 



CHAPTER XVI. 



INSECTS AND ANIMALS INJURIOUS TO THE VINE. 



Our most formidable insect enemy, the phylloxera, has al- 

 ready been discussed in a previous chapter. Other insect 

 enemies are not 'so formidable, though sometimes injurious 

 enough. Perhaps the worst of these is the little white thrip, 

 a leaf hopper, a little midge of a thing, which feeds on the 

 under side of the leaves, causing them to dry or drop, when 

 the fruit can not fully ripen, and therefore will not develop suf- 

 ficient sugar. Early summer pruning is one of the aids to pre- 

 vent exposure to the sun, as the young laterals will retain their 

 leaves much longer. But sulphuring with bellows will also 

 serve as a partial remedy, and kindling small fires in the 



