998 



Lime-Sulbhur as a Fungicide. 



[Feb., 



In the experiments, where a substance was added to lime- 

 salphur in order to increase its wetting powers, calcium casemate 

 was found to give very satisfactory results. This substance, 

 which has been used by A. Peterson (12) in conjunction with 

 lime-sulphur as an insecticide, has not hitherto, we believe, been 

 used for improving lime-sulphur as a fungicide for use in 

 summer. It may be mentioned here that the substance known as 

 saponin considerably increases the wetting properties of lime- 

 sulphur (13) but the mixture was not found satisfactory for deter- 

 mining the fungicidal values of lime-sulphur solutions, whereas 

 calcium casemate gave admirably consistent results. In the 

 first experiments 1 per cent, of calcium casemate was used with 

 lime-sulphur (1.30 sp. gr.) at the dilutions 1 : 99, 1 : 149 and 

 1 : 199, containing, respectively, 0.16, 0.11 and 0.08 per cent, of 

 poly sulphide sulphur. At the first two strengths, the solution 

 proved fungicidal, all the patches of mildew on the sprayed 

 leaves being dead when examined 24 hours after spraying, while 

 the mildew-patches on the " control " leaves, sprayed with 1 per 

 cent, of calcium casemate alone were as vigorous as before. At 

 the strength 1 : 199. the lime-sulphur solution was clearly not 

 quite fungicidal — many of the patches were killed but several 

 survived and produced new conidiophores and chains of eonidia. 



In another experiment the same lime -sulphur was used at the 

 dilution 1 : 99 with 0.5 per cent, of calcium caseinate, and here 

 again proved completely fungicidal.* 



It seems probable, therefore, that the strengths at which 

 lime-sulphur is being used in this country against mildews, viz., 

 1 part of the concentrated wash (1.30 sp. gr.) to 29. or 59, parts 

 of water are to be regarded as super-fungicidal and that weaker 

 strengths, viz., 1 to 74, or 1 to 99, will be found to be fungicidal 

 when used with calcium caseinate in order to secure complete 

 wetting. t Should this prove to be the case, and with regard to 



* In one experiment a calcium polysulphide solution, made in the laboratory, 

 was used at the dilution 1 : 75 (when it contained 0.33 per cent, of poly- 

 sulphide sulphur) with 1 per cent, of calcium caseinate and found to be 

 completely fungicidal. 



f The calcium caseinate solution was prepared by stirring two parts of 

 commercial casein and one part of slaked lime in twenty parts of water for 

 about two hours and allowing any undissolved solid to settle. The supernatant 

 liquid, used without filtration (which is extremely slow and unsatisfactory), 

 is, roughly, a 10 per cent, solution of calcium caseinate, and half a gallon 

 or one gallon of it is used in the preparation of ten gallons of lime-sulphur 

 wash according as one desires to have 0.5 or 1 per cent, of calcium caseinate 

 present. The preparation by the farmer of the calcium caseinate solution 

 would be a tedious process ; it is confidently expected, however, that this 

 substance will be put on the market in this country by manufacturing horticul- 

 tural chemists, as a similar substance, for use with arsenate of had, is 

 sold commercially in the United States of America. 



