Slimmer Meeting. 63 



spray we have one or two, or three elements, according as we put the 

 materials in. In mine the Bordeaux is the poison and lime the carrier. 



W. L. Howard — Bordeaux mixture proper is a chemical union and 

 in a solution combines with the lime. In the dust form it is ordinarily- 

 separate, there is no real union but only a mechanical mixture. 



E. H. Favor. — If quick lime is ground up and the sulphate of cop- 

 per ground, when the mixture is applied the moisture on the leaf forms 

 the chemical union. But with air-slaked lime such a union will not be 

 formed, if the ground quicklime stands exposed to the air it will become 

 slaked. 



T. H. Todd. — When I use air-slaked lime and the powdered sul- 

 phate I find the same color when the moisture strikes the dust as in 

 regular Bordeaux, the color is blue in the dust, I use twenty-five pounds 

 of copper sulphate to one hundred of lime. 



Mr. Favor. — The insoluble compound is greenish, but we get the 

 blue color a great deal. If w^e could use quicklime it might do, but we 

 cannot get it. The air-slaked and the copper do not make true Bordeaux. 



Mr, Todd. — The powdered lime would burn the hands. 



Mr. Favor. — If the lime burns it must be quicklime as it gives off 

 heat, but no amount of heat is given off with air-slacked lime. 



B. C. Auten. — It is impractical to pulverize copper sulphate so that 

 it will carry in the air. The copper sulphate is heavy and descends pure 

 on the men, hence the blue color. Does the lime counteract the scalding 

 of the copper ? 



Mr. Favor. — This mechanical dust mixture burns more than the 

 liquid because the copper is not finely divided and the particles do not 

 scatter as well but stick together. The lime and copper sulphate cling 

 together in separate balls and the burning that results is as bad as the 

 fungi. The liquid scatters the particles better. We have been using at 

 the experiment station both Mr. Maxiwell's and Dr. Bird's formulas. 



Mr. Todd. — I made the trees white with the powder and now the 

 leaves are blue but healthy. 



Mr. Favor. — The air-slaked lime and the copper give an insoluble 

 compound, and consequently does not burn the foliage. 



J. M. • Irvine. — Mr. Maxwell used the mechanical mixture and 

 burned his foliage. He sprayed seven times and yet has scab in his 

 orchard, the spray w-as ineffective and both apples and trees have the 

 scab. Have you scab on your sprayed trees? 



Mr. Favor. — Yes, the sprayed trees have the scab badly this year. 

 If the spraying is carried out faithfully we may control the scab next 

 year. If we quit spraying early it gives the scab all summer to grow. 



