DUSTS 31 



Early experiments in dusting- trees were made 

 with dry Bordeaux and an arsenical. In this mix- 

 ture the copper was the essential fungicide. The 

 following is a formula ^^ (Scott's), for this dust: 



4 lbs. copper sulphate in 4 gals, water 

 4 lbs. lime in 4 gals, water 

 60 lbs. slaked lime dust 



Dissolve the sulphate in the 4 gallons water and 

 slake the lime in the 4 gallons. When cool pour 

 together and allow it to settle. Decant or pour off 

 the liquid, put the wet mass in a strong- bag and 

 squeeze out the remaining water. Then spread out 

 and allow to dry in the sun. Pulverize this dry ma- 

 terial and pass it through a sieve with 80 meshes to 

 the inch and then mix with the 60 pounds of slaked 

 lime. For Bird's formula see Mo. Bull. 60 or Cor- 

 nell Bull. 216. 



Comparative early experiments indicated that six 

 applications of the dry material could be made as 

 cheaply as four with liquid. The dust is more easily 

 transported about an orchard, especially if the 

 orchard is roug-h. It does not appear to have any 

 other advantage, accordino^ to early experiments. 



The dust did not control fungous diseases as well 

 as liquid Bordeaux. The dust proved irritating to 

 workmen, getting into their lungs. 



Crandall ^^ says the ''dust spray is absolutely in- 

 effective as a preventive of injury from prevailing 

 orchard fungi, and that it is considerably less effi- 

 cient as an insect remedy than is the liquid method 

 of applying arsenites." 



It must be remembered that these experiments 

 were made with a Bordeaux dust. 



64 Scott— U. S. Dept. Agr., Far's' Bull. 243, p. 11. 

 Craig— Cornell Univ. Expt. Stat.. Bulls. 216, 245. 

 Close — Delaware Expt. Stat., Bulls. 72 and 76. 



65 Crandall— Illinois Expt. Stat., Bull. 106. 



