88 THE GEAPE ROOT-WOKM. 



PRESSURE TO BE MAINTAINED IN SPRAY APPLICATIONS. 



In order that effective results may be obtained with poison sprays 

 it is A^ery desirable that, as nearly as possible, all of the foliage be 

 covered with a mistlike spray. (See fig. 30.)' Since in many vine- 

 yards having thrifty growing vines the foliage is quite dense during 

 the latter part of June and early July it is necessary that this finely 

 divided spray be thrown into the vines with considerable force. For 

 effective work a steady pressure of not less than 100 pounds should 

 be maintained and if this can be increased to 125 or 150 pounds still 

 better work may be accomplished. 



SPRAYING APPARATUS. 



In order to cover vineyard areas of several acres in this manner it 

 has become necessary to use power sprayers and during the past few 

 years several types of power vineyard sprayers have come into use. 



Horsepower sprayers. — Geared sprayers operated by horsepower (PI. X, figs. 4, 5) 

 are in general use in many vineyard sections. There are a number of sprayers of 

 this type upon the market. With many of them, however, it is difficult to maintain 

 a sufficiently high pressure to cover thoroughly all of the foliage without driving 

 through the vineyard at too rapid a rate. In addition to this the nozzle arrangement 

 is not adjusted so as to cover the foliage on the top of the trellis. A very unpleasant 

 feature in the operation of many of these machines is that the driver is seated directly 

 between the nozzles which are attached to the sides of the machine and consequently 

 is drenched with the spray. It would seem however, that with a little ingenuity on 

 the part of the manufacturers this unpleasant seating position and ineffective nozzle 

 arrangement could be satisfactorily adjusted. 



Gasoline-engine sprayers. — Many vineyardists prefer to have the power for pro- 

 viding pressure independent of the rate at which the machine travels through the 

 vineyard and more directly under the control of the operator than it is with the geared 

 sprayers. Since, however, the regulation gasoline-engine outfit used for spraying 

 orchards is too heavy and cumbersome to use in the narrow rows of vineyards it has 

 become necessary to mount the tank and machinery on a specially constructed shortened 

 truck having low front wheels to admit of easy turning into the narrow vineyard rows. 

 Plate X, figure 2, is an illustration of this type of gasoline-engine vineyard outfit and 

 is the sprayer used for the past three seasons in making the application of poison 

 sprays in the field experiments conducted during this investigation. An outfit of 

 this kind has the additional advantage of being adaptable for use as an orchard outfit 

 by simply disconnecting the fixed nozzles at the pump and connecting a lead of hose 

 and rod when wishing to spray trees. It was for the purpose of tree spraying that the 

 derrick or platform was erected above the tank. When used for vineyard work the 

 derrick proved useful as an elevated seat where the driver would be clear of the spray. 

 (See PI. X, fig. 2.) 



Compressed-air outfits. — Compressed-air outfits are a type of sprayer which find 

 favor with a number of vineyardists and perform excellent work. The air is com- 

 pressed by means of a stationary engine at the loading station and one of the cylin- 

 drical tanks is charged with air and the other filled with the spray liquid. The two 

 tanks are connected so that the air may pass into the tank containing the liquid and 

 force it out through the nozzles in the form of a fine spray. Since there is no machin- 

 ery connected with this sprayer except at the loading station there is practically 

 no danger of delay from machinery getting out of order while working in the field. 



