PROCEEDINGS 1918 37 



and arsenic, have yet to be worked out for various plants. It 

 is unlikely that the dust can be used for the first application 

 after the blossoms on the apple, because of the liability of rus- 

 seting the fruit. It is likely that it will be several years be- 

 fore the best proportions for this dust for various plants and dis- 

 eases are worked out. We are still working with liquid Bor- 

 deaux mixture and still have much to learn in regard to it, and 

 if we have the new dust down to a good working basis in five 

 years we shall have done well. 



In looking up the literature on Bordeaux in preparing an 

 article for this publication, it was noted that Millardet the 

 French Chemist, who developed Bordeaux mixture, conducted 

 in 1886 an extensive series of experiments with dusts. Among 

 the several dusts tried was one composed of anhydrous copper 

 sulphate, air slaked lime, and sulphur. This particular dust 

 was reported as giving the best fungus control of any of the 

 dusts used. The dust method of applying fungicides was ap- 

 parently dropped because it could not be put on a commercial 

 basis. If hydrated lime had been on the market at that time, 

 and available for mixing with the anhydrous copper sulphate, 

 the result might have been quit3 different. 



The dust here described has proved promising in experi- 

 ments, and is worth further trial, particularly in testing the 

 proportions of copper and arsenic; but it will be some time be- 

 fore its relative efficiency with liquid Bordeaux mixture will be 

 definitely known, and before it can be generally recommended. 



