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133 



Fig. 69. Leaf of York -Madeira. 



resistance to phylloxera, contrary to what has generally been 

 said, is not high, and may be represented by the number n. 

 Its development is slow, even under conditions where the 

 phylloxera does not check it. It only thrives well in 

 northern regions, where it is an excellent graft-bearer, but 

 only in fresh, pebbly soil, composed of siliceous or hard 

 calcareous pebbles ; it is equal in .vigour to other graft- 

 bearers in stiff clay-siliceous soils. But, under these con- 

 ditions, Rupestris is far superior. 



In slightly fertile soil the York-Madeira remains very 

 weak; its grafts are not vigorous, although they bear much 

 fruit, but the fruit does not ripen well. In chalky calcareous 



