316 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



this year it reduced the crop of grapes in France over 75 per cent., in 

 many districts totally destroying the crop. 



Discovery of the Utility of Sulfur. After 1854, the grape growers 

 of France commenced to learn how to control the disease. The use of 

 sulfur for this purpose, discovered and perfected between 1850 and 

 1853, soon became general, and by 1859 the crop of grapes had reached 

 its normal volume in France. The effect of Oidium in diminishing the 

 crop and the effect of sulfur in controlling the disease in one depart- 

 ment of France is well shown by fig. 1. This figure, which is adapted 

 from one published in the nursery catalogue of F. Richter, Montpellier, 

 indicates also the destruction of French vineyards by Phylloxera and 

 their rehabilitation by means of resistant vines. The rapidity with 

 which sulfur enabled the French grape growers to reestablish their 

 vineyards is in contrast with the slow r er process of controlling the phyl- 

 loxera. In three or four years after the use of sulfur became general 

 in the Herault the crops had reached their normal volume. It has 

 taken twenty years to reestablish the same vineyards on phylloxera 

 resistant stocks. 



OIDIUM / X PHYLLOXERA 



SULFUR 



VINES 



RESISTANT 



Fig. 1. Showing (1) the reduction of crop of wine in the Herault from 3,900,000 

 hectoliters in 1850 to 1,000,000 hectoliters in 1856 by the attack of Oidium; 

 (2) the rapid increase of crop after the general use of sulfur; (3) the re- 

 duction by phylloxera of the crop from 15,200,000 hectos in 1869 to 2,100,- 

 000 hectos in 1885; and (4) the gradual increase due to the use of resistant 

 vines. 



Damage done by the Disease in California. In California the 

 Oidium has never produced such wide-spread and serious injury as 

 that indicated above. This arises principally from the dryness and 

 heat of the atmosphere during summer in most of our grape-growing 

 regions. The dryness of our climate is undoubtedly the cause of our 



