NEW YORK EXPERIMENT STATION BULLETINS. 369 



No. 13. Sulphate of copper, \ pound dissolved in 22 gallons of water. 



Dates of 

 applica- 

 tions. 



July 13. 



" 28. 



Aug. 11. 



" 20. 



Plants used. 



Apple (Alexander) ... 



Pear (Hoivell) .*... 



Quince (Champion) ... 



Peach (Doivnton) 



Grape (Moore's Early) 



Egg-plant 



Potato (Early Rose)... 



Dates of observation and per cent, 

 of injury. 



July 23. Aug. 8. Aug. 22. Sept. 5 





 

 

 25 

 

 

 





 

 

 40 

 

 

 



No. 14. Sulphate of copper, \ pound dissolved in 22 gallons of water. 



Dates of 

 applica- 

 tions. 



July 23. 



" 28. 

 Aug. 11 



" 20. 



Plants used. 



Apple (Alexander) . 



Pear (Howell) 



Quince (Champion) . 

 Peach (Hardwick) ._ 

 Grape (Rochester) _ . . 



Egg-plant 



Potato (Early Rose) 



Dates of observation and per cent, 

 of injury. 



July 22. Aug. 8. Aug. 22. Sept. 



5 



10 

 

 50 

 

 

 



10 

 20 

 

 60 

 

 

 



These tables show that all the plants were injured except the quinces, 

 egg-plants, and potatoes, a result which was unexpected, since the use of 1 

 pound of the sulphate of copper dissolved in 25 gallons of water has been 

 recommended for mildew on grapes. 



Two combinations were made with each of the above formulas, using 

 Paris green and London purple at the rate of 1 pound in 200 gallons of 

 water, with each one. The combinations containing Paris green caused on 

 the average 20 per cent, more injury than when the arsenite was not used. 

 The London purple combinations increased the injury of the sulphate only 

 10 per cent. As the varieties treated were not the same, this result can not 

 be regarded as conclusive. The effect of these solutions upon fungi was 

 unsatisfactory. 



Conclusions. — The action of the commercial sulphate of copper upon 

 foliage is uncertain. 



The injury done by the sulphate of copper solutions is increased from 

 10 to 20 per cent, by the addition of arsenites. 



HYDEATE OF COPPER (FROM LABORATORY) AND ARSENITES. 



Copper appears in the Bordeaux mixture in the form of the hydrate. 

 The following shows the reactions which take place in preparing the Bor- 

 deaux mixture, and its final composition when prepared according to the 

 formula: 



6 pounds copper sulphate. 



4 " lime. 



22 gallons of water. 



47 



