i9c6] AS A FUNGICIDE. 163 



Sprayed with solution of sulphuric acid i to looo, on December 7, 

 8, 9, 10, .12, 14, 16 and 19, with the result that the mildew was com- 

 pletely eradicated, the new growth was vigorous and the mildew 

 did not reappear. 



A few months later another lot of roses growing in the green- 

 house were treated. These included pink rambler, crimson rambler, 

 Victoria rambler, bridesmaid, golden gate, liberty, American beauty 

 and Carnot. The plants were sprayed with sulphuric acid solution, 

 I to 1000, on January 9, 10, 11, 12, 15 and 17, with results similar 

 to those obtained in the previous experiments. I have also used 

 the spray since with similar results. 



In conclusion I may add that it appears that dilute solutions of 

 sulphuric acid have a beneficial effect on the plants treated apart 

 from their fungicidal action. In fact they seem to act as a tonic to 

 the host plant while they kill the mildew. 



Should subsequent experiments confirm the results here recorded, 

 it will be found that sulphuric acid has certain advantages over 

 sulphur, in that it does not discolor the foliage as sulphur does, its 

 employment is more easily controlled, and it does not have the dis- 

 agreeable odor of certain other compounds associated with sulphur. 



Inasmuch as the antiseptic properties of sulphurous acid are well 

 established, it may be possible that a combination of sulphuric and 

 sulphurous acids in solution would be more effective than sulphuric 

 acid alone. Taking the proportions in which these acids are formed 

 when sulphur is heated, it may be that a solution containing i part 

 of sulphuric acid and o.i to 0.0 1 part of sulphurous acid to 1000 

 parts of water, would be more effective than sulphuric acid alone 

 in the proportion given. 



