10 DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 
was carried. The cause of this great variation in pressure was due 
to the fact that it is impossible to wet the underside of all of the 
leaves if the machine is stopped at frequent intervals. 
The spray was applied to the underside of the foliage by means 
of what is known in vineyard spraying operations as a “ trailer ”— 
that is, instead of delivering the spray to the foliage from nozzles 
attached to a fixed rod upon the spraying machine a 4-inch hose 
from 20 to 40 feet long is attached to the discharge of the pump. To 
the free end of this lead of hose is connected a 41-inch rod about 
24 feet long carrying either one or two nozzles of the cyclone type set 
upward at right angles to the rod. This short rod is held by the 
operator and is thrust in among the leaves of the vine and quickly 
moved about and withdrawn, requiring rapid movements in order 
to cover the underside of all of the leaves and at the same time not 
waste much of the liquid. The operator must always bear in mind 
that the spray liquid must come in contact with each individual 
nymph that is to be destroyed. This is the only method known to us 
at present of making a liquid spray application effective. We have 
made several attempts to deliver the spray to the underside of the 
foliage by means of nozzles fixed to the machine but have achieved 
only partial success by that method. 
By many vineyardists this “trailer” method of application has 
been considered slow and expensive. Yet, as worked out this season 
on the experimental plats of the Bureau of Entomology it has not 
proved more so than applications made for other vineyard pests. 
The cost of the application on the vineyard of Mr. H. H. Harper 
at North East, Pa., was as follows: Blackleaf tobacco extract at a 
dilution of 1 to 150 cost approximately one-half cent per gallon. 
The area of vineyard covered per day was 3 acres, and the items 
of expense were as follows: 
Onenman*toloperate spray rode 22 eee per day—— $1. 75 
Team@etovhaul ‘Sprayers. 222s. ee eee Gost p25 25) 
One boy to drive team. ee doses 00 
Cost, ofispray, liquid for 3°acres=] === eee eee dons — "2540 
Total Cost. for .3:aCheS-_ 2.8 Se ee 7.40 
Total cost per acre 22825222) 2 ee ee ee 2.47 
A block of 11 acres of badly infested vineyard belonging to Mr. 
G. E. Pierce was sprayed July 14 to 16 with blackleaf extract, using 
1 gallon of the extract to 100 gallons of water. The “ trailer ” method 
of application was employed as in the previous experiment. In this 
instance, however, two nozzles were used and about 200 gallons of 
liquid were applied per acre. This increase in the strength of the 
liquid and of the quantity employed raised the total cost of the appli- 
cation to $3.75 per acre. <A part of this increased cost of application, 
however, was occasioned by trouble with the water supply during 
