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 J-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 J-inch rod about 

 2J 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 moved about and withdrawn, requiring rapid movements in order 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: 



One man to operate spray rod per day $1. 75 



Team to haul sprayer do_J 2. 25 



One boy to drive team do 1.00 



€ost of spray liquid for 3 acres do 2.40 



Total cost for 3 acres 7. 40 



Total cost per acre 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 



