Third Report on Potato Culture. 



179 



Records of Potato Plats, 1898. 



Spraying operations. — Early in the growth of the potatoes 

 spraying became necessary. In addition to the Colorado potato 

 beetle (Doryphora decemlineata), the leaf-flee-beetle (Crepidodera 

 cucumeris) early began its depredations. Bordeaux mixture and 

 Paris green used freely served to check both insects. Several 

 farmers have informed us that the Bordeaux mixture has failed 

 with them to check the work of the leaf-fiee-beetles, but with us 

 for three years in succession it has proven effective in checking, 

 although it has not entirely driven them away, Bordeaux mix- 

 ture made and tested with the ferrocyanide of potassium proved 

 very satisfactory. 



Directions for making Bordeaux rnixture. — Directions were 

 given in Bulletin 140 for making Bordeaux mixture. We have 

 found that the ferrocj^anide of potassium test is much simpler 

 and so the following directions are given : 



Into a barrel of w^ater suspend a gunny sack or other porous 

 bag, containing two pounds of copper sulfate for every gallon of 

 water in the barrel. If this is suspended near the surface of the 

 water at night it will all be in solution by morning and ready for 

 use. Into a water tight box or other open receptacle place some 

 fresh burned caustic lime, the amount to be determined somewhat 

 by the amount of spraying to be done, but from 40 to 50 pounds 

 of lime can be easil}^ slaked at one time. Add sufficient water to 



