194 



MANUAL OF MODEKN VITICULTURE. 



Fig. 167. Section of a Vine Root attacked by 

 Rcesleria (after E. Prillieux). 



result may be obtained by deep cultivation and drainage r 

 which removes the excess of water, and renders the soil 



unfit for the develop- 



O. . . i> v f~~^ - - . . - . - 1 - 



, ^ftooife 



i2agioo 



ment of the disease.* 

 To clean the soil one 

 must carefully remove 

 all the roots and burn 

 them on the spot so 

 as to avoid the dif- 

 fusion of the spores, 

 which might take 

 place if the roots were 

 carried away. The 

 affected spot is sur- 

 rounded by a trench 

 18 inches deep, the 

 soil being thrown in- 

 wards, and a treat- 

 ment of bisulphide of 

 carbon at the rate of 600 Ibs, per acre applied. All the 

 fragments of roots and fungi in the ground are killed.. 

 A few days after the soil may be planted again. 



3RD. MALADIES. 



Chlorosis. Vines affected by chlorosis become yellow on 

 ace cunt of the insufficient formation of chlorophyl. 



Most American vines are much more sensitive than 

 European vines to the action of this malady; however, we 

 have seen (page 55) that some species are not affected. 



Th3 grafting of European vines on American stocks gene- 

 rally causes an increase in chlorosis, although sometimes, 

 but very rarely, it diminishes it. We may often notice 

 Riparias becoming yellow after grafting, although they 

 remain green when not grafted. On the other hand 

 chlorosed Herbemont were endowed with a fine vegetation 

 after being grafted with European vines. Amongst our 

 Southern ce"pages, those which seem to improve the condi- 

 tions of existence of varieties upon which they are grafted 

 are Clairette and Carignane. 



The chlorosis of American vines is generally due to the 

 presence of limestone in the soil ; this was studied when 



* See introduction to Trenching and Subsoiling for American Vines, by R. Duboia 

 and W. Peicy Wilkinson. Melbourne, 1901. 



