171 



-on, when the leaf dries, some of these spots remain green. 

 If, during this period, the weather is very dry, some of the 

 brown spots fall away, leaving a hole in the leaf. 



Mildew also occurs on all the green parts of the vine in 

 the shape of white patches. When on the flowers, it causes 

 non-setting; if on the shoots and grapes, it causes these 

 organs to become brown and fade away, but without ever 

 producing canker. 



The bunches of grapes are only attacked by mildew when 

 they are very young, and sometimes, but rarely, at their 

 turning point, when they are completely covered with fructi- 

 fications of mildew, which entirely stops their development. 

 If they are attacked later on, the skin becomes brown and 

 hard in places ; in this case the fructifications of the fungus 

 may not appear outside, but take place inside in the space 

 existing between the seed and the pulp, as Prillieux 

 ascertained. According to some authors the effects of this 

 disease are identical with those of the disease known in 

 America under the names of gray-rot and common-rot. 



The berries attacked by mildew sometimes become brown 

 around the pedicle, the alteration gradually reaching the top 

 of the berry. , Engelmann pointed out this difference in 

 America, where it is known under the name of brown-rot in 

 Missouri. When the peduncle and pedicle are attacked by 

 the disease they may dry and fall away. It was this action 

 of lesions which caused, in 1885, the loss of the greater part 

 of Jacqtiez crop in certain regions of the Herault. 



CE*PAGES MOST LIABLE TO MILDEW. 



The cepages of the old world which seem to suffer most 

 from mildew are Grenacke* Cariynane, Bobal, Cinsaut, Cot 

 or Malbeck, Opiman, Kawouri, Rosaki, Farrana, (Eillade, 

 Mataro, &c. 



Amongst the American vines, according to Meissner,f are V. 

 ^Estivalis: Elsinburgh^ Eumelan, V. Labrusca: Adirondac^ 



* Mildew is often confused with Erineum, which is the gall of an acarien para'ite. 

 (Phytoptm vitis or Phytocoptes vitig). The leaves attacked by mildew are never bulged, 

 and the erineum always attacks the leaf on the upper face. The parasite puucturesthe leaf, 

 which develops on the under face a dense felt of hair, coating the gall, always widely open. 

 These hairs are bright white at the beginning, and are often confused with the white 

 efflorescence of mildew. They never have the woolly white appearance of mildew, and are 

 adherent. The part of the leaf bulged by the puncture of the parasite always remains green 

 on the upper face. As the galls become older, the hairs become brownish, the tint 

 increasing in intensity. These stiff hairs are constituted by a few superposed cells with a 

 thick membrane, becoming thinner towards the top, the last one having the shape of a 

 point. They are much stouter than the fructiferous filaments of mildew, and naturally do 

 not bear any reproducing organs. 



t Bush and Meissncr, Illustrated descriptive catalogue of American Grape Vines 

 St. Louis, 1883. [Transls.] 





