258 INJURIOUS INSECTS. 



SUSCEPTIBILITY OF DIFFERENT VINES TO THE DIS- 

 EASE. As a means of coping with the Phylloxera dis- 

 ease, a knowledge of the relative susceptibility of different 

 varieties to the attacks and injuries of the insect is of 

 paramount importance. As is often the case with injurious 

 insects, the Phylloxera shows a preference for and thrives 

 best on certain species, and even discriminates between 

 varieties; or, what amounts to the same thing, practi- 

 cally, some varieties resist its attacks, and enjoy a rela- 

 tive immunity from its injuries. It may be stated that 

 there is a relation between the susceptibility of the vine 

 and the character of its roots the slow-growing, more 

 tender-wooded, and consequently more tender-rooted 

 varieties succumbing most readily; the more vigorous 

 growers resisting best. The European Vine ( Vitis vini- 

 fera), in its many varieties, is little affected by the leaf- 

 inhabiting type, but it succumbs in a few years to the 

 root-lice. Varieties of the Northern Fox-grape ( V. La- 

 bruscd) vary much; some, like the Concord and others, 

 resist well, while others, like the Oatawba, suffer severe- 

 ly. Varieties derived from V. cestivalis and F. cordifo- 

 lia are nearly exempt from the root-form, but some of 

 them have the leaves much attacked by the gall-type. 

 The Southern Fox-grape ( V. vulpina) is entirely free 

 from Phylloxera in any form. 



EEMEDIES AND PREVENTIVES. Thus far, the only 

 practicable method of combating the insect when estab- 

 lished upon the root, is by drowning it by irrigating the 

 soil. In Europe, the method largely adopted is to graft 

 their vines upon varieties, the roots of which are Phyl- 

 loxera proof ; for this purpose American varieties have 

 been sent to Europe in immense numbers, as cuttings 

 and as rooted plants. An enterprising grape-growing 

 firm has even established nurseries in Europe for the pro- 

 duction of vines that resist the Phylloxera. 



