•274 Fungicidal Properties of Certain Spray-Fluids 



2. Experiments with "Lime-Sulphur" and its Constituents. 



Tliese experiments — preliminary to a contemplated study of the 

 fungicidal and insecticidal properties of a mixture of lime-sulphur and 

 arsenates — were for the purpose of ascerta,imng to which constituent or 

 constituents of lime-sulphur the fungicidal property of this spray-fluid 

 is due, and also to determine the exact strength of such constituents 

 fungicidal for the "powdery" conidial stage of S. Humidi. 



It was found(20) that the addition of a solution of calcium caseinate 

 — a substance first used with a fungicide, apparently, by Vermorel and 

 Dantony(i3) — increased the wetting powers of lime-sulphur so satis- 

 factorily that its fungicidal properties at various dilutions could be 

 accurately measured. Concordant results were obtained when a solution 

 of lime-sulphur of a certain strength, to which a solution of calcium 

 caseinate had been added, was compared, using the method described 

 below, with a hme-sulphur solution alone of the same strength. Some of 

 the details of these experiments may be given here, since they serve also 

 to show the close approximation of the lower hmit of the fungicidal con- 

 centrations and the upper hmit of the non-fungicidal concentrations of 

 hme-sulphur for the particular fungus. 



The method employed was — since a soap solution cannot be used 

 with hme-sulphur for chemical reasons — first to spray the mildew with a 

 1 per cent, soft soap solution (which removed the air entangled among 

 the conidia and conidiopkores and wetted all the parts), then to spray 

 thoroughly with water to remove the soap solution, and immediately 

 afterwards with the hme-sulphur solution. Observations showed that 

 the treatment with soft soap and then with water had no deleterious 

 effect on the mildew, since by the fourth day after treatment (and often 

 earher) the sprayed mildew-patches were fully as vigorous and as 

 powdery as the imsprayed ones on the "control" leaves. 



In the following two experiments the Ume-sulphur solution was 

 applied after the preliminary treatment described above. A commercial 

 brand of hme-sulphur ("Sulfinette") of 1-30 sp. gr. and containing 

 16-57 per cent, of polysulphide sulphur was used. 



Experiment 10. Lime-sulphur, 1 part to 99 parts of water (0-16 per 

 cent, polysulphide sulphur). The solution proved completely fungicidal. 

 Experiment 9. Lime-sulphur, 1 : 199 (0-08 per cent, polysulphide 

 sulphur). On the fourth day after sprajnng the mildew- patches were all 

 barren. By the sixth day scattered conidiophores had appeared from 

 some of the patches, while the remaining patches were still barren. These 



