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out or allowed to run wild on account of this disease, which, at the 

 time, was little understood. 



Although one of the most troublesome of the grape vine 

 diseases, it is at the same time one of the easiest to subdue, pro- 

 vided that the treatment be carried out with care. 



Like all powdery mildews, the parts attacked are covered over 

 by the web-like threads of the mildew fungus. It only attacks 

 those organs when green. It at first appears as a dirty white 

 powdery film, possessing a characteristic mouldy smell. It leaves 





Oidium of the Vine. 



stains on the wood. Should it appear early, the flowers will fail to 

 .set; then the more tender leaves will be covered with patches of 

 microscopic threads, which will stop their growth and cause them to 

 shrivel up and dry. The berries are most severely attacked. The 

 effect of the parasite on the skin is to tighten it and cause it to 

 loose its elasticity, so that the berries either dry up or burst open. 

 The ripening does not progress satisfactorily, and, when fermented, 

 the juice produces a nasty wine with a mouldy taste or flavour, and 

 one which does not keep well. 



Varieties most attacked by oidium, and cultivated in Australia, 

 are: Albilio, Cariguane, the Cabernets, Chasselas, Black Ham- 

 burgh, Gouais, the Muscats, (OEillade, Pedro Ximenes, Eiesling), 

 Roussanne (White Hermitage), Shiraz' (Black Hermitage), Tokay 

 (Green Hungary), Trebbiano (Ugni Blauc), Yerdeilho, and a great 

 many table grapes. 



Varieties not much attacked. Aramon, Dolcetto, Grenache 

 (Eoussillon), Mataro (Mourvedre), Marsanne (White Shiraz), the 

 Pinots (Burgundy), Sauvignon, Morrastel, Aspiran. 



Varieties least attacked. Malbec, Catawba, and Isabella, two 

 varieties of an American vine (F. Ldbrusca), and, in fact, most 

 American vines. 



