660 INSECTS AFFECTING VEGETATION 



the work. The platform can be arranged with a roadway on its up- 

 per side so that the lime and bluestorie can be delivered there, while 

 the spray tank is filled from the lower side. (F. B. 243.) 



The Water Supply. A water supply of some sort is necessary ; 

 a tank filled by a windmill pump and elevated so as to be a few feet 

 above the dilution tanks is a great advantage. Hose may be used to 

 fill the dilution tanks, or an iron pipe with a spigot may be placed 

 over each tank. Each dilution tank should hold half the quantity 

 it is desired to make up at one time that is, if a 200-gallon spray 

 tank is to be filled the dilution tanks must hold about 100 gallons 

 each. There is no objection to adding a few extra gallons of water, 

 but it is better to have the tanks hold just the right quantity. 



Methods of Mixing the Solutions. Either of two methods of 

 mixing can be employed : One in which the spray material is con- 

 ducted directly from the dilution tanks into the spray tank and act- 

 ually mixed in this tank; the other in which a mixing tank sits just 

 below the dilution tanks and from which the spray, after being 

 mixed up, is conducted by gravity into the spray tank. In certain 

 ways the latter is more convenient than mixing directly into the tank, 

 but unless the operations are somewhat extensive it will hardly justify 

 the extra expense. In very large operations, however, a separate 

 mixing tank is recommended or perhaps even two of them side by 

 side so that batches of the mixture can be kept on hand for a few 

 moments awaiting the spray wagons. 



Testing Bordeaux Mixture. When Bordeaux mixture is prop- 

 erly prepared it is of a brilliant sky-'blue color. If the lime is air- 

 slaked or otherwise inferior in quality, resulting in a bad mixture, 

 the preparation will have a greenish cast, and if this is very pro- 

 nounced, the mixture will injure the foliage. 



In order to make certain that the copper sulphate is properly 

 neutralized by the lime, the yellow prussiate of potash test may be 

 used. A small bottle containing a 10 per cent solution of yellow 

 prussiate of potash can be secured from a druggist. After stirring 

 the Bordeaux mixture, a drop of this solution is allowed, to fall on 

 the surface of the preparation. If free copper is present, the drop 

 will immediately turn reddish-brown in color. Lime should then be 

 added until the brown color fails to appear. If the reaction is com- 

 plete, the yellow prussiate of potash solution will remain a clear yel- 

 low until it disappears in the mixture. 



Adding Insecticides. One advantage of Bordeaux mixture is 

 the possibility of adding arsenical insecticides to the preparation and 

 thus of spraying at the same time for diseases and for the codling 

 moth and leaf-eating insects. Paris green, at the rate of one-quarter 

 pound to 50 gallons of Bordeaux mixture, may be considered as the 

 standard formula for this purpose. London purple, arsenate of lead, 

 and other arsenicals may be used in the same way. Bordeaux mix- 

 ture may be considered as so much water in the formulas for this 

 class of insecticides. As a matter of fact, the slight excess of lime 

 in the standard mixture renders it an especially suitable medium for 

 distributing these insecticides. 



