162 BOARD OF, AGRICULTURE. [Pub. Doc. 



in the case of the Bordeaux mixture, but in a state of complete 

 solution. As soon as the ammonia evaporates, which is very 

 quickly, the insoluble oxide of copper only remains. The 

 action of other preparations in which the carbonate of copper 

 is dissolved in cither caustic ammonia or the carbonate, is 

 almost precisely similar, the carbonate being as insoluble in 

 water as the oxide. They are applied in a state of solution, 

 but become at once insoluble as soon as the moisture is fully 

 evaporated. 



Notwithstanding the unscientific character of these various 

 preparations of copper for the purpose in view, there is no 

 question but that much good has come out of their use, 



although the results contain a good deal of contradiction 



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among themselves. I think it possible to reconcile some of 

 these, but do not care to occupy your time to speculate upon 

 the subject now. In their place I venture to propose, as a 

 complete substitute, the use of the simple solution of sulphate 

 of copper. It is free from most of the objectionable features 

 that apply to other preparations of this metal. Its operation 

 as a fungicide is decided and unquestioned. The substance 

 readily dissolves, and is in no way detrimental if properly 

 applied, either by its present or ulterior effects, and does 

 not disfigure the foliage. The only difficulty heretofore has 

 been that it was used at such a degree of strength as to act 

 as a caustic, and thus destroy more or less of the substance 

 of the leaves to which it was applied. This is easily avoided, 

 although it has been a matter of much careful experiment to 

 ascertain the strength at which its ill effects are entirely 

 wanting. It has this peculiarity, that it does not show all of 

 its injurious action for some days or even weeks after appli- 

 cation, and we are therefore liable to be misled in its use. 

 Although my experiments, more especially during the past 

 season, need repetition and verification before too much 

 confidence is based upon them, I feel prepared to recommend, 

 as the best general fungicide now available, a solution of 

 sulphate of copper, one pound to eight hundred gallons of 

 water, two ounces to one hundred gallons, one ounce to the 

 barrel of fifty gallons. So far as I have learned, no injurious 

 effects have followed from an application of this strength, 

 while as a fungicide it contains one part of metallic copper 



