70 
THE GRAPE ROOT-WORM. 
Table XXV and indicate a much greater efficiency from the arsenate 
of lead application than from the application of arsenite of lime. 
Vineyardists throughout Erie County have practically abandoned 
the use of arsenite of lime as a poison spray against the grape root- 
worm beetle, and arsenate of lead is now used almost exclusively. 
RESULTS OF VINEYARD EXPERIMENTS WITH POISON SPRAYS. 
The field experiments of this investigation were carried on during 
the three consecutive seasons of 1907, 1908, and 1909, and in view 
of results obtained by spraying by the senior author during his single 
season of cooperative work with the late Prof. M. V. Slingerland 
the remedial measures tried out were almost entirely along the line 
of spray applications, it being his belief that the j^ost effective results 
could be obtained by this method of combat. Some of the principal 
points upon which information was desired were the effect of poison 
sprays in ridding the vines of the grape root-worm beetles, the effect 
of this application in preventing egg deposition by beetles, the rela- 
tive effect of this treatment on vines of different ages and different 
stages of infestation, the determination of the immediate seasonal 
benefit to the vines by prevention of egg deposition, and the cumu- 
lative benefit both in vigor of vines and crop yield obtained by 
following up a line of treatment for several consecutive seasons. 
A brief survey of vineyard conditions in the townships of North 
East, Pa., during the late summer of 1906 enabled us to make a 
selection of vineyard areas in the various stages of infestation and 
decline best suited to the working out of these problems. A block 
of vineyard owned by Mr. Roscoe Davidson, of North East, was 
selected for the experiment to determine the effect of poison appli- 
cations. The conditions existing in this vineyard were well suited 
to the plan of experiment. The area was about 12 acres, thus mak- 
ing it possible to secure results of commercial value. The vineyard 
(PI. VI) is situated on a northern slope and is divided into four 
blocks or sections. The soil is of a loose gravelly texture. The 
lower northern section consists of young Concord vines about 7 
years planted, the two sections immediately above are made up of 
vines about 20 years planted and are referred to as old Concords, and 
the south section consists of a block of 7-year-old Niagara vines 
referred to in these experiments as young Niagaras. At the time 
the experiment was undertaken the whole block showed a uniformly 
heavy infestation of larvae on the roots of the vines. With the excep- 
tion of the section of young Concords, however, the vines had not 
yet reached the stage of serious decline and were still producing 
fairly profitable crops. With the young Concords the case was 
different. Our attention had been called to these vines late in the 
summer of 1906 at the time when the fruit was commencing to color. 
