46; 



Journal of Agriculture, Victoria. 



[lo July, 191 i. 



VINE DISEASES IN FRANCE. 



{Continued from page 398.) 

 F. dc Castclla, Government Viticulturist. 



Mildew {Plasmopara viticola). 



Mildew, or Mildiou, as it is phonetically spelt in French (the " W " 

 in that language being pronounced like our " V "), is caused by a fungus 

 radically different from that of Oidium, in its botanical relationships, in- 

 its mode of life, and in the methods by which its ravages can best be 

 combated. 



Though its recognised botanical name is now Plasmopara viticola, it 

 was long known as Peronospora Viticola, and is 'Still often referred to 

 in France, as well as in America, as Peronospora. 



Botanically. it belongs to the family of Peronosporea and the great 

 fungus group of Oomycefes, and is closely allied to the potato blight 

 (PJi vtofhtlwra iiifestaiis). 



1 . 2. 



DOWNY MILDEW (Plasmopura viticola). 



I. L'nder surface of vine leaf showing characteristic white tufts (after Charter' n). 

 2. Diagrammatic section of leaf attacked by mildew showing mycelium (black) 

 between cells of tissue and summer spore-bearing hlanients on under side. The 

 large round bodies, buried in the tissues of the leaf, are oospores [after Vialla)- 



Though long known in the eastern States of the North American Union, 

 it was not until 1878 that mildew was observed in France; after this, its 

 spread was exceedmgly rapid, not only .in France, but throughout the 

 whole of Europe, the damage done varying much according to local climntic 

 conditions. Should these be suitable, it becomes one of the most serious 

 scourges that vignerons can have to fight against. 



In outward appearance the disease is easily recognised and distinguished 

 from other fungi. It attacks all growing parts of the vine, but it is on the 

 leaves that it can be most readily recognised. Its American name of 

 Downy Mildew verv aptly describes it, and ex])lains the chief difference 

 which distinguishes it from Powderv Mildew or Oidium. The latter 

 fungus has the appearance of a thin white or greyish powder, the general 



