II March. 1918. 



Vin eya rd Sp railing. 



14o 



Potato-growers, on tlie other hand, have to deal with a low-growing 

 crop, Avliich can he rapidly saturated with the spray. Several fixed 

 nozzles are so arranged that one or tAvo will treat a row of potatoes ; 

 several rows are thus simultaneously treated, thus enabling a large 

 area to be treated in a short time by a continuously advancing outfit. 

 The machine shown in Fig. 5 can be used for spraying potatoes or 

 low-growing vines. 



The vine really occupies a position intermediate betAveen the fruit 

 tree and the potato, both as regards the size of the plant itself and the 

 time required to treat it. Even among vines requirements vary greatly, 

 according to the distance between the rows, the size of the vines, and 

 the arrangement of the vines in the row. In trellised vines, the growing 

 portions of which are in contact throughout the whole length of the 

 row, continuous spraying is possible. In staked vines, on the other 

 hand, the work is preferably intermittent ; a continuously acting spray 

 would, mean a loss of spraying material at the interval between the vines. 



Fig. 7. — Vermorel's Modification of the Riley 

 Nozzle (after Viala). 



Knapsack Sprays. 



Since the introduction of spraying in French vineyards, knapsack 

 spray pumps have, until recently, been most generally used. (Fig. 6.) 

 Before passing on to the consideration of the larger machines which 

 are gradually displacing them, these may be briefly described; the 

 essential parts of both are similar, and can more conveniently be sum- 

 marily described in connexion with the smaller knapsack naachines. 



All spray innnps consist of three essential parts — (1) a reservoir to 

 contain the spray mixture; (2) a nozzle l>y which the liquid is converted 

 into a fine spray or mist; (3) a punij) Iv nu ans of which the liquid is 

 conveyed under pressure to the nozzle. Fi i use with copper mixtvire, the 

 reservoir must be made of copper or soir.e metal on which these liquids 

 have no action. It is usually proviJ d with an agitator, which serves 

 to keep the sediment — really the active portion of the mixture — in 

 ^us])ension. 



Most of the nozzles now in use are modifications of Riley's original 

 cyclone nozzle (Fig. 3), which onsists of a small, hollow cylinder, into 

 which the liquid is brought under pressure by the oblique passage A. 

 The cylinder is closed by a metal cap, pierced in its centre by a small 

 aperture. It will be seen that the liquid is forced in tangentially, this 



