THE GR.\PES OF NEW YORK. 5 



relative from the eastern hemisphere, but these few are such as to make 

 them now and probably ever tlie only grapes possible to cultivate in America 

 in the commercial vineyards east of the Rocky Mountains. Indeed, but 

 for the fortunate discover}- that the vine of Vitis vinifcra could be grown 

 on the roots of any one of several species of the American grapes, the vine- 

 yards of the Old World grape would have been almost wholly destroyed 

 within the last half century because of one of its weaknesses. This destruct- 

 ive agent is the phylloxera,' a tiny plant louse working on the leaf and root 

 of the grape, which in a few years wholly destroys the European vine but 

 does comparatively little harm to most of the American vines. Three other 

 pests are much more harmful in the Old World vineyards than to the vines 

 of the New World; these are black-rot {Guignardia bidwellii (Ell.) V. & R.), 

 downy mildew {Plasmopara viticola (B. & C.) Berl. «& De Toni), and powdery 

 mildew (Uncimila necator (Schw.) Burr.). 



The susceptibility of the Old World grape to these parasites debars 

 it from cultivation in eastern America and so effectually that there is but 

 little hope of any pure-bred variety of it ever being grown in this region. 

 American viticulture must, therefore, depend upon the native species for 

 its varieties, though it may be hoped that by combining the good qualities 



' The phylloxera {Phylloxera vastatrix Planch.) has four forms: the leaf-gall form, the root 

 form, the winged form, and the sexual form. Individual leaf insects produce from 500 to 600 eggs, 

 the root insect about 100, the winged insect from 3 to 8, and the sexual insect but i. The last is laid 

 in the fall on old wood; the following spring a louse hatches from it and at once goes to the upper 

 surface of a leaf and inserts its beak. The irritation thus produced causes a gall to form on the lower 

 side of the leaf. In fifteen days the louse becomes a full-grown wingless female and proceeds to fill 

 the gall with eggs after which it dies. In about a week females hatch from the eggs and migrate to 

 form new colonies. Several generations of females occur in a summer. At the approach of winter 

 the lice go into the ground where they remain dormant until spring when they attack the roots 

 forming galls analogous to those on the leaves and passing through a series of generations similar to 

 those above ground. In the fall of the second year some of the root forms give rise to winged 

 females which fly to neighboring vines. These lay eggs in groups of two or four on the wood of 

 the grape. The eggs are of two sizes; from the smaller size, males hatch in nine or ten days; 

 from the larger, females. In the sexual stage no food is taken and the insects quickly pair. The 

 female produces an egg which fills its entire body and after three or four days lays it, this being the 

 winter egg, the beginning of the cycle. 



There are no remedies worthy the name and the only efficient preventive is to graft susceptible 

 varieties on resistant stocks. Species are resistant about in the order named: V. rotundijolia, V. 

 riparia, V. rupcstris, V. cordiloliii, V. berlandieri, V . tiiit-rt'd, I', aestivalis, V. candicans, V. labrusca, 

 V. vinifcra. 



