EXPERIMENT STATION BULLETINS. 



DC) 



form) it is necessary to multiply by the factor (I. If the amount of lead 

 arsenate is expressed in terms of arsenic oxide (As.^O.,) then it is' neces- 

 sary to multiply by the factor 3.93. 



Example. A sample of Bordeaux-Lead Arsenate was guaranteed by the 

 manufacturer to contain 1.50 per cent copper (Cu) and 5.25 per cent 

 arsenic oxide (AsoOj). Using the method already described we find that 

 the mixture should contain 5.90 per cent crystallized copper sulfate (1.50 

 X 3.93=5.90) and 20.04 per cent lead arsenate (5.25x3.93=20.61). The 

 manufacturers recommend that 8 pounds of this particular material be 

 diluted with water to 50 gallons. Therefore, when ready for spraying the 

 50 gallons would contain 0.47 pound of crystallized copper sulfate (0.059 

 X 8=0.47) and 1.05 pounds of lead arsenate (0.2004x8=1.05). The 

 equivalent amount of lead arsenate paste is approximately double that of 

 the dry form. 



As previously stated the formula most generally recommended for mak- 

 ing bordeaux is 4-4-50 though for some purposes a 2-2-50 formula may be 

 used. When it is desired to conibiue an insecticide witli the fungicide lead 

 arsenate is usually employed at the rate of 2 to 5 pounds of the paste 

 or 1 to 2l^ pounds of the dry powder to 50 gallons of the diluted bor- 

 deaux mixture. 



As a general rule it will be found tliat the commercial bordeaux:- 

 arsenate preparations do not contain the essential ingnMlieuts in the 

 I)roportions that have been found by practice to give the best results. The 

 poison is usually greatly in excess of the fungicide and when used accord- 

 ing to the usual recommendations of the manufacturers tlie preparations 

 could hardly be expected to possess very powerful fungicidal powers. 



BORDEAUX MIXTURES 



