258 



I^^JUFJOUS INSECTS. 



SrSCEPTIBILITT OF DIFFEEZXT TrS"E5 TO THE DIS- 

 EASE. — As a means of cojiing with, the Phylloxera dis- 

 ease, a knowledge of the relative snsceptibility of different 

 Yai'ieties to the attacks and injuries of the insect is of 

 paramount importance. As is often the case with, injurious 

 insects, tlie Phylloxera shows a jn-ef erence for and thrives 

 best on certain species, and even discriminates between 

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

 cally, some vai'ieties resist its attacks, and enjoy a rela- 

 tive immunity from its injuries. It may be stated that 

 there is a relation l^etween the stisceptibility of the vine 

 and the character of its roots — the slow-gi'owing, more 

 tender-wooded, and consequently more tender-rooted 

 varieties sticcumbing most readily; the more vigorous 

 growers resisting best. The Etiropean Tine {Vitis vini- 

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

 inhabiting t^-j^e. but it succttmbs in a few years to the 

 root-lice. A'arieties of the Xorthem Fox-grape ( T. La- 

 hrusca) vary much: some, like the Concord and others, 

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

 ly. Varieties derived from Y. cpstivalis and F, cordifo- 

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

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

 The Southern Pox-grape [V. vul^jina) is entirely free 

 from Phylloxera in any form. 



PiE^rEDizs AXD Peevextives. — 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 Euroj^e for the pro- 

 duction of vines that resist the Phylloxera. 



