EXPERIMENT STATION BULLETINS. 537 



sui-e enough lime has been used. If raris-greeii, arsenate of h'ad, or any 

 other poison is to be used, make it into a thin paste with a little water 

 and add it to the Bordeaux-mixture, which is now ready to be used. 



COPPER SULPHATE SOLUTION, 



Copper sulphate solution is copper-sulphate dissolved in water. It is 

 used by some growers to si)ray peach trees to prevent the leaf curl where 

 a spraying for scale insect is not required. Two pounds of copper- 

 sulpliate to 50 gallons of water is strong enough for this purpose. 



Prepared Bordeaux. There are many brands of prepared Bordeaux- 

 mixtures upon the market, sold under various proprietary names. Some 

 of them also contain arsenical poisons. In our tests of thes(» materials, 

 we have not found them as efficient or as economical in controlling fung- 

 ous diseases as a properly home-made Bordeaux. 



POISONS USED IN SPRAYTNO. 

 Far Injects That Chew. 



ARSENATE OF LEAD. 



This poison is used very extensively. It can l)e obtained cillier as a 

 paste or as a dry powder. The powder is alunit twice as strong as iIm' 

 paste, and only half as much of it is re(iuired in preparing spray mix 

 tures. Consequently it usually costs about twice as much as the paste 

 per pound. Arsenate of lead is ready for use at any time and does not 

 readily injure foliage. Furthermore, this poison can l)e safely used in 

 the lime-snl[)hur sprays. Injuiy to tender foliage lil<<' tlie peacii lias 

 occasionally occurred after spraying with arsenate of lead .nn] walci- 

 when the foliage was moist fi-om dew oi- i-ain. AVhcn it is lu'ccssary lo 

 spray such tender foliage as that of i>eaches or .Japanese plums, it is well 

 to add from three to five pounds of freshly slaked or of hydrated lime 

 it) 50 gallons of poison spray, 



A simple easy way to work the thick pasty arsenate of lead into a 

 thin, smooth paste is to put the amount required in a keg, add water and 

 churn with a dasher, such as is used in an oMI'ashioned stone churn. 

 The mixture is made much more quickly than when a paddle is used 

 for stirring. 



ARSENATE OF CALOIT'M. 



A new arsenical spraying material is coming into the market at the 

 present time — arsenate of calcium. It has been tested to some extent 

 during the past season, notably on potatoes and apples, and seems to 

 reseinlde arsenate of lead in its nature and in its action on chewing in 

 sects. It costs a little less than arsenate of lead and is designed to 

 take the place of the latter poison. This substitution would be desiralde 

 because of the necessity for using lead in ..thei- ways. Arsenate of 

 calcium is sold as a very finely ground powder, and when used at the 

 rate of 15% with hydrated lime or with other diluent it seems to be 

 entirely successful in dusting operations. It can also be combined with 



