188 



EXPERIMENTAL FARMS 



9-10 EDWARD VII., A. 1910 



AGRICULTURAL BLUESTONE. 



Under variou? names substitutes for copper sulphate as a fungicide are continu- 

 ally being put upon the market. These are for the most part mixtures of sulphate of 

 iron and sulphate of copper. As we have rei)eatedly shown that the former is much 

 inferior as a fungicide to the copper compound, and especially so in the destruction 

 of smut spores in the treatment of wheat, these mixtures must be regarded as far 

 less efficacious than bluestone. Occasionally the claims made for these preparations 

 are of an exceedingly extravagant character, and the prices asked exorbitant and out 

 of all proportion to their composition. It is well, therefore, for the farmer and fruit 

 grower to remember, when these compounds are offered him, that sulphate of iron is a 

 very much cheaper material — and a much less valuable compound as a fungicide — 

 than bluestone. 



In our last annual report the analysis of ' Anti-Fungi ' — a material of this nature 

 manufactured in New York and widely advertised in northwestern Canada for the 

 treatment of grain — was given ; this year we present data respecting three samples of 

 materials of like character forwarded to the laboratory for examination and report : — 



Analysis of Agricultural Bluestone. 



A. ' Agricultural bluestone," forwarded by a correspondent in Brandon, Man., 

 ■who -writes as follows : — ' The wholesale house handling this compound state " that it 

 gives equally good results as sulphate of copper as a fungicide and is considerably 

 cheaper." ' The claim that it is the equal of sulphate of copper for fungicidal pur- 

 poses is far from correct, for it contains nearly 60 per cent sulphate of iron, a com- 

 pound, as we have pointed out, of much lower fungicidal qualities. 



B. ' Agricultural powder J — This is most probably identical with the sample dis- 

 cussed in the preceding paragraph. It was sent to us by a large wholesale and import- 

 ing house in Montreal, who were anxious to know whether, as claimed, it could be 

 recommended to take the place of copper sulphate. 



C. ' Copper sulphate hi-product.' — The firm sending the material under this 

 name state that ' it is about to be offered to the agriculturists and fruit growers of 

 Canada as a substitute for sulphate of copper,' and are anxious to know ' if it would 

 be effective in the making of Bordeaux mixture.' The data show the presence of sul- 

 phate of iron to the extent of almost 50 per cent. It would not, therefore, have the 

 same efficiency, weight for weight, as sulphate of copper for the treatment of wheat. 

 Further, we do not consider that this material could be used effectively as a substitute 

 for copper sulphate in the preparation of Bordeaux mixture, for not only would the 

 spray be of little value as a fungicide but the hydrated oxide of iron precipitated by 

 lime would tend to clog the nozzle, making the application of the spray a difficult 

 operation. 



Samples * A ' and ' C ' had somewhat effloresced ; that is, lost a part of their water 

 of crystallization by exposure to dry air. This furnishes the explanation for the sum 

 of the amounts of their constituents being greater than 100, the percentages of iron 

 and copper sulphate being calculated to the crystalline form. 



