WINE-MAKING IN CALIFORNIA. 185 



the propagation of oidium, and a good shower will do much 

 to remove and destroy the germs. 



As to temperature, .the disease begins its development 

 where the average of day and night runs up to 53 F.; it 

 spreads rapidly at 70 F., and is checked in its growth where 

 the thermometer indicates near 100 F. Above 100 its 

 damage is rapidly diminished, and at 112 a temperature 

 quite common throughout the interior vineyard districts of 

 California the germs loose their vitality and the effects of 

 the disease entirely cease. 



To be sure, where vines make a dense growth and are 

 trained high above the ground, the germs may be so sheltered 

 in shady spots as to escape the effects of the heat. Where, 

 on the contrary, the vines are trained along or close to the 

 ground and receive the reverberated in addition to the direct 

 heat of the sun, the manner in which vines should be trained 

 then, the high temperature above named accomplishes a 

 complete extermination of the parasite, a result which- has 

 often been noted in Algiers where such temperatures are fre- 

 quent throughout the early growing period of the vine. 



Let it be borne in mind generally that the propagation of 

 the oidium and other vegetable parasites of the vtne are great- 

 ly favored by trellises and high training. Short pruned vines 

 and those trained close to the ground are most exempt from 

 fungoid diseases. 



A hot north wind will sweep the oidium from a vineyard 

 well exposed to its effects. This forms one of nature's most 

 common remedies in California, and should be a consolation 

 to those who may otherwise lose by it in the grain field. 



Some varieties of vines are found more susceptible to the 

 attack of oidium than others, other conditions being similar 



This fact should influence the vineyardist as to the fre- 

 quency of Applying the remedy and the amount of sulphur 

 employed . 



