OBSERVATIONS ON SOME VINE DISEASES IN SONOMA COUNTY. 



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grapes falls to the ground. Such is the progression of the disease in 

 the grapes while they are still green, but, when they begin to mature 

 the shrinkage becomes less total as the absolute percentage of sugar 

 increases in the fruit. 



The fruit of diseased vines, when it does not shrivel, often ripens 

 prematurely. This prematurely ripened fruit is frequently edible, 

 though sometimes quite distasteful. 



The manner in which the malady works on the different bunches of 

 the same cane is quite characteristic. The lower bunch of grapes is the 



FIG. 4. Bunches of grapes showing progress of Grape-shrivel. 



first to show signs of the disease; it is not rare for one to find the lowest 

 bunch much diseased, and the upper just beginning to show the first 

 nigns. We have even found, on canes bearing three bunches of grapes, 

 the first bunch completely desiccated, the second shriveled, and the 

 third absolutely sound. There are canes, however, in which the differ- 

 ences are less marked, and some even in which the progression of the 

 disease is reversed. 



Effect of the Disease on the Leaves. The disease does not show in the 

 foliage at first. The leaves of strong, healthy vines and strong, healthy 

 shoots remain turgid and green; the leaves of weaker vines and weaker 



