POTATOES 357 



dangerous to handle than formaldehyde, although it, too, is a 

 deadly poison. ' Both solutions must be used with the utmost care. 



Spraying. The fact that the early, varieties of potatoes used by 

 truck farmers and market gardeners are as a rule dug before full 

 maturity renders the necessity for spraying somewhat less impera- 

 tive than in the more northern sections, where large yields depend 

 upon maintaining growth as late in the fall as possible. 



Spraying with arsenicals for the beetle is necessary except in 

 the extreme South, and injuries from arsenical poisoning, tipburn, 

 and the early-blight fungus are so general that spraying with Bor- 

 deaux mixture and an arsenical combined should become the estab- 

 lished farm practice. The poison may be either Paris green or 

 arsenate of lead, from 2 to 4 pounds to 50 gallons of water. The 

 former burns the leaves when used alone and in large quantities, 

 but not when applied with Bordeaux mixture. The Bordeaux 

 mixture is not a poison to the beetle, but acts as a partial deter- 

 rent. It also diminishes the tipburn, probably by protecting the 

 plants against excessive loss of water and by direct stimulation. 



Preparation of Bordeaux mixtttre. To make the Bordeaux mix- 

 ture on a small scale take two half-barrel tubs, one for the copper- 

 sulphate solution and the other for the milk-of-lime solution. Place 

 5 pounds of lime in one tub and slake this with sufficient water to 

 break up thoroughly the lime without allowing it to burn. After 

 the lime is thoroughly slaked dilute it to 25 gallons. Into the other 

 tub pour 2 5 gallons of water and suspend in it 5 pounds of copper 

 sulphate in a gunny sack or other porous sack from 24 to 48 hours 

 before the solution is required. Bordeaux mixture is then made by 

 pouring these two solutions through a wire-cloth sieve which has 

 about 1 8 or 20 meshes to the inch, equal quantities of the two so- 

 lutions being poured at the same time through the strainer, which 

 should be suspended over a barrel or other receptacle sufficiently 

 large to hold 50 gallons of the mixture. In making this combi- 

 nation it is best to have two men dipping simultaneously from the 

 two receptacles and pouring the two solutions together into the 

 strainer. The milk-of-lime and the copper solutions should at all 

 times be kept thoroughly stirred. 



When large quantities of Bordeaux mixture are required, stock 

 solutions are made in 5<D-gallon casks, the concentration of the 



