THE RAISIN INDUSTRY. 95 



Untinula also develops so-called peritheca. It is more than probable 

 that both fungi belong to the same species, but until these perithecal 

 organs have been found on the European Oidium, the proper name for 

 our mildew must be Untinula, and not Oidium. It is also probable 

 that the Untinula fungus is a native of this continent, and that it from 

 here has spread to Europe, where the natural conditions are such that 

 only the gonidial form of the fungus has been able to develop. In 

 general appearance and in their effects the Untinula and Oidium are 

 identical. 



The Oidium appears sooner on poor soil and on exhausted vines, and 

 vines in which the flow of the sap for some reason or other has been 

 checked are more subject to the mildew than those which are yet 

 in full growing vigor. Elevated vines on trellises which are much 

 exposed, and vines which are so covered up that the air has little access, 

 are the first ones to be attacked, and those which will suffer the most. 

 The powdery mildew affects all varieties of grapes, but some kinds 

 more than others. The Muscats are among those which suffer consid- 

 erably, and if not sulphured would in severe cases neither set nor 

 bear suitable grapes. The Malaga is less affected, and so is the Sul- 

 tana. In new districts the Uncinula does not appear until the vines are 

 older. Thus in the Fresno district the earliest vines did not suffer from 

 mildew until they became five years old, but now the mildew would de- 

 stroy the grapes every year, in case they were not treated with sulphur. 



Remedies. The most common and perhaps the best remedy is pow- 

 dered sulphur. The latter is applied either with the dust can or 

 " dredger," or with bellows. The dust can is used when the vines or 

 vine shoots are yet small, and the bellows when the vines are larger. 

 The first sulphuring should be done when the young shoots are six 

 inches long, immediately before the bloom, and the second time when 

 the berries are well set. Sulphuring as a regular vineyard operation 

 will be more fully discussed further on. 



DOWNY MILDEW OR PERONOSPORA. 



General Notes. The downy mildew is a fungus known botanically 

 as Peronospora mticola. Its native country is the United States, but its 

 greatest damage is done in Europe. It appears as white, downy 

 spots- on the underside of the grape leaves, which are gradually 

 destroyed, and later on attacks the berries, which shrivel and spoil. 

 In California the downy mildew occurs frequently on wild native 

 grapevines, but only very rarely on the cultivated Asiatic vines. 

 Dr. H. W. Harkness, the eminent mycologist, found it only once on 

 cultivated vines in the Sacramento river bottom. These vines were 

 growing close to native vines, from which the fungus had spread. 

 There is no fear that this fungus will ever spread and cause damage in 

 our State as long as the vineyards are given plenty of air. In France 

 the Peronospora has caused much damage, but is now being com- 

 bated with bluestone and lime solutions, according to the follow- 

 ing formula: Slake thirty pounds of lime in seven and a half gallons 

 of water, also mix sixteen pounds of bluestone (copper sulphate) in 

 twenty-five gallons of water. Mix the two together, and either sprinkle 



