BULLETIN 197. 



GRAPE CULTURE IN CALIFORNIA. 



151 



Without mature green leaves the buds and canes do not receive the 

 stores of starch which they need for the new growth in spring, and 

 will either grow poorly the following year or fail to start at all. 



When a new growth of leaves in autumn follows summer defoliation 



FIG. 15. Brunissure on Tokay leaves. 



by hoppers, mildew, or other causes, the effect is even worse. The new 

 shoots which start exhaust what food reserves the vine possesses, 

 and the leaves are killed by the early winter frosts before they have 

 been able to return the supplies they have taken from the canes. 

 Similar, but less severe, effects have been observed following a bad 

 attack of Oidium. 



