590 ANNUAL REPORT OF THE Off. Doc. 



the most injurious insect to be found in the vineyards of that sec- 

 tion. This insect injuries the grape vine by sucking the juice from 

 the foliage. The winged adult -hoppers" winter to some extent 

 among trash and rubbish present ii^ vineyards, but by far the greater 

 number of them migrate from the vineyards in the fall and hiber- 

 nate beneath leaves and dense grass in adjoining wood lots, sod 

 lauds, and fence rows. When the gi-ape vines unfold their leaves 

 in the spring these winged adults return to the giape vines and after 

 feeding for a few weeks deposit their eggs beneath the pubescence 

 on the underside of the leaves. 



The nymphs or youug "hoppers" connuence to appear on the 

 underside of the leaves about the middle of June. Usually by 

 the end of June they are present in lai-ge numbers varying in size 

 from those just hatched to those with fully developed Aving pads. 

 It is in this nymphal stage that this pest may be most successfully 

 controlled by the application of a contact spiay. Since the insect 

 obtains its foods by inserting its proboscis into the tissue of the leaf 

 and sucking the juices therefrom, poison applications to the surface 

 of the foliage are of no avail. The nymphs must be actually hit 

 and covered by some spray substance which will cause death by con- 

 tact. 



In a number of field experiments which have been conducted in 

 the township of JS^orth East, Pa., during the past two years, the 

 tobacco extracts, such as Black leaf extract and a more concentrated 

 form of Black Leaf 40, have given very satisfactory results. The 

 chief requisites for success being that the applications be made be- 

 fore nymphs have changed to the winged or adult form, and that 

 the under side of practically all the infested leaves be made thoroughly 

 wet by the spray. 



The Black Leaf Extract was found to be effective at a dilution 

 of 1 to 150 parts of water and the Black Leaf 40 at a dilution of 

 1 to 1,500 parts of water. All of tHe applications were made by the 

 "trailer" method. That is, a man operates a nozzle by hand to 

 apply the spray to the underside of the grape foliage. This nozzle 

 throws the spray upward by being set at right angles to a short rod 

 held by the operator and is connected to the spray pump by means 

 of about 20 feet of trailing hose. The spray is applied to the under- 

 side of the leaves by thrusting the nozzle into the foliage upon the 

 trellis by a series of rapid movements on the part of the operator. 



Effective results have been obtained by several types of sprayer. 

 For economy and expedition, however, a pressure of not less than 

 100 pounds should be available. Although effective Avork can be 

 done at even a lower pressure. With high power outfits two leads 

 of hose can be operated thus greatly expediting the work. W^ith a 

 single lead of hose from 2^ to 3 acres of vineyards per day can be 

 covered. With two leads this area can be about doubled. The 

 amount of liquid applied varies from 175 gallons to 275 gallons per 

 acre depending on the density of the foliage to be sprayed. 



The total cost of labor and material varied from about $."^.00 

 to 15.00 per acre according to the amount of liquid applied and the 

 efficiency of the machinery employed. The net benefit in several of 

 these experiments varied from .|9.00 to 117.00 per acre in the in- 

 creased yield of grapes as the result of one application for a single 

 season. 



