38 AMERICAN VINES. 



intense, or at least of shorter duration, the third year t'.ian 

 it was in the second 



Maturation therefore takes place under better conditions 

 and during a longer time; also, at the fourth year, and 

 for the same reasons as previously given, the yellow colour 

 is less marked, if it has not totally disappeared. 



Chlorosis and Mildew. All causes placing an obstacle in 

 the normal functions of the cells of the vine hinder the 

 formation and accumulation of reserve matters, and there- 

 fore the subsequent development of the vine. An increase 

 of chlorosis results. Mildew, by prematurely causing the 

 leaves to fall, acts in this manner, as was apparent enough 

 in the years 1883, 1885, and 1886, when the chlorosis was 

 very intense, and the mildew, not yet combated with cupric 

 salts, had exceptional gravity. 



Chlorosis and Phylloxera. Phylloxera acts in the same 

 way, hindering the growth of the vine by the lesions it 

 determines on the roots. A marked weakness soon becomes 

 apparent, and, under the circumstances, it is less resistant to 

 the carbonate of lime. Everybody has seen phylloxerated 

 vines becoming intensely yellow in calcareous soils (never in 

 any other soils) before succumbing. The phylloxera, by 

 weakening the vine, renders it more sensitive to the action 

 of carbonate of lime; their effects however accumulate, and 

 this is why vines resist the phylloxera less in calcareous 

 soils than in clay-siliceous soil. 



The same phenomena take place with the American vines 

 not absolutely resistant, but to a lesser extent. The non- 

 success of many plantations made with American vines must 

 be attributed to the simultaneous action of phylloxera and 

 soil; in a word, phylloxera diminishes the facility of adap- 

 tation to soil of American vines which are not very resistant. 

 Consequently, the less resistant American vines should always 

 be planted in soils which are the least noxious to them. 



The lesions due to the white grub or any other parasite 

 attacking the roots is attended with the same consequences. 



Chlorosis and Grafting. Grafting results in a relative 

 diminution of the vigour of the vine (we will later on ex- 

 plain the reasons why), as well as its resistance to phylloxera, 

 and also induces it to become yellow. Every one has noticed 

 this. But this weakening effect is only produced when the 

 species or varieties grafted differ from each other. In very 

 calcareous soils, the Folle-Blanche grafted on its own roots 



