lo July,. 1911-] Vif/e Diseases in France. 463 



appearance gradually becomes darker owing to the discolouration of the 

 underlying tissues. This powdery appearance is distributed generally over 

 the leaves and other growing parts on the upper and under surfaces alike. 

 In the case of Mildew the white downy efflorescences, characteristic of 

 the fungus, are almost invariably situated on the under surface of the leaf. 

 The upper surface, at these points, presents a discolouration, slight, and 

 usually yellowish at first, but finally becoming of a dark reddish 

 brown colour. The downy tufts, usually of a milky white colour, but some- 

 times greyish, are very di.stinct, and cannot be mistaken for any other 

 fungus. In the case of a bad attack, the leaves fall off, sometimes together 

 with the leaf-stalk; at others, they detach themselves at the junction of 

 t"he limb and the stalk, leaving the latter adhering to the vine. 



The complete suppression of the leaves, when the berries are about the 

 size of buckshot, naturally entails the destruction of the crop, and this 

 would frequently be caused but for spraying with copper mixtures, which 

 have now become indispensable operations in all the vineyards of France. 

 By means of these sprayings, more or less complete protection of the foliage 

 is achieved. Injury to foliage, even when not sufficient to greatly reduce 

 the yield, may lead to a reduction in the quality of the wine. Pessimists 

 sometimes tell one that the wines of France are not equal to what they were 

 a generation ago; they attribute this to the fact of grafting on resistant 

 stocks, a contention which has been recently and abundantly proved to 

 be absolutely false.* Reduction of quality, if any, is due to the ravages 

 of Mildew, and, in certain seasons at least, there can be no doubt that 

 such reduction does occur. In addition to this indirect damage, the fruit of 

 the vine is subject to direct attack, and this at different periods of the 

 growing season. 



An early invasion of Mildew, about blos.soming time, or shortly after, 

 when the bunches are young and tender, may bring about the complete 

 destruction of the crops in the space of a couple of days. This form of the 

 disease is termed in French Mildiou de la Grappc (bunch mildew). Such 

 •disastrous visitations are sometimes experienced as a result of neglect of 

 the first preventive treatments, which, experience has shown, should in- 

 variably be applied. A little later in the season, the bunches may also be 

 attacked. Their appearance, more or less covered with the efflorescence 

 of the fungus, has led to the term Rot-Gris (Grey Rot) being used at this 

 stage. Berries thus attacked wither and dry up. If attacked before 

 maturity, when the fruit is about to change colour, the whole of the pulp 

 is invnde'd by the fungus. The fruit then becomes soft and discoloured. 

 This form, termed in French Rot-Brun (Brown Rot), may seriously injure 

 the quality of the wine. 



The diagram reproduced shows the mode of life of the Mildew fungus. 

 Its mvcelium grows exclusively in the interior of the tissues ; never on the 

 .surface, as is the case with Oidium. It is only the fructifications which appear 

 en the outside of the plant. These, as shown in the diagram, consist of much 

 "branched filaments bearing the conidia or summer spores by which the spread 

 of the fungus is carried on during the summer months. These are pio 

 dured in enormous numl>ers. They are light and easily carried Ijy the wind, 

 facts whicli explain the extraordinarily rapid spread of the di.sease. 

 These spore-bearing filaments constitute the milky white down, visible to the 



• Thi- cfTi-ct of uT.'iftin;,' i>n resistant stocks on Mif iinalit.v of tlio wiiif was fxliauslivtOy (HsiussihI at 

 the IntiTiiutional \ iticiiltiirol Conu'ross o( Antrcrs in li)(i7. The exiilonco tluTiM'ulU'fli'd from all parts o' 

 tiie w "rill proved that the fai't of jfraflinsr "n resistant stocks led to no re<luction in tlie nualitv of the 

 wine. 



