64 FOURTH ANNUAL REPORT OF 



Eiver Bank grape next, and the Summer grape the least affected. It woukl 

 likewise appear that galls are occasionally found on all of the species ex- 

 cept the European, and as they have in a few instances, been found on this 

 species in Europe, it cannot be considered entirely exempt.* Nevertheless, 

 in general terms, the Eiver Bank gi-ape must be considered the si^ecies which 

 the gall-louse prefers. Experience on this point will, no doubt, vary in dif- 

 ferent parts of the country, and more extended exjierience may modifj' some 

 of these deductions. 



We thus see that no vine, whether native or foreign, is exempt from 

 the attacks of the root-louse. Yet, on the principle that a small dose of poi- 

 son may prove harmless or even beneficial whore an over-dose will kill, we 

 find that a small number of root-lice produce no serious effects upon the 

 vine ; and that it is only where they are very numerous, and cause not onlj' 

 the fibrous roots, but even the larger ones to waste away, that their evil 

 effects are perceptible. With most of our native vines when the conditions 

 are normal, the disease seems to remain in the former mild state, and it is 

 only with the foreign kinds, and with a few of the natives^ under certain 

 conditions, that it takes on the more acute form. 



In France, according to M. Laliman, the American varieties which have 

 resisted the root-louse best are the Clinton, Taylor, lierbemont (known there 

 as Warren), and some others which are considered valueless here, such as 

 Pauline, Elsimboro, Lenoir, Mustang of Texas, and a kind of York-Madeira^ 

 while those which succomb are Isabella, Scuppernong, Concord, ]S"orton's 

 Virginia, Maxatawn}", Hartford Prolific, Cynthiana, etc. This exijerieuce 

 differs a little from ours, but shows that the Lahruscas suffer most there 

 also. 



MEANS OF CONTAGION FROM ONE VINE TO ANOTHER. 



The young lice, whether hatched upon the roots or in the galls, are 

 fj^uite active and crawl about for some time; and that they will spread from 

 one vine to another, either under ground upon the roots or on the surface 

 of the ground during the night, is highly probable. Such, however, cannot, 

 be the mode of spreading from one vinej-ard to another; for were it so, the 

 malady could not possibly have assumed such proportions in so short a time, 

 as it has done abroad. One method of transport is upon the roots of seed- 

 lings and cuttings, but the insect cannot in this manner find its way to an 

 old vineyard, and there must be still another means. Here we come to that 

 part of the natural history of our louse which must assume the form of hy- 

 pothesis until further observations shall be made. In this country the mal- 

 ady is general, but in France, where it is still spreading from one place to 

 another, they have a good opportunit}^ to watch its progress ; and Planchon 

 finds that it always commences at certain circumscribed points and spreads 

 from these points in more or less regular circles. There is no way of ac- 

 counting for these nuclei — these starting points in the center of an old vine- 



* Since this was written I have been informed bv Mr. Glover, of the Oepartment of Agrieulture, 

 tliat the leave.s of certain Kuroi)ean vines, in green-house, such as Muscat Hamburg und Madam Piine 

 were crowded with the galls, even as late as December; and that they had begun to spread on t.. so«- 

 ora and the Due de Malucqff'. 



