300 Fniu/lcidal rropertlcH of Certain Spray-fliiMh 



patches were killed, but a few on each leaf produced a very few conidio- 

 phores at the edges), while on these leaves sprayed with the lime-sulphur 

 solution although some of the patches were killed, most regrew some 

 clustered conidiophores. On leaves 7, 8, 9, the ammonium sulphide 

 solution had the same effect as that described above for the leaves 2-5 

 sprayed with lime-sulphur, while the lime-sulphur solution on leaves 

 7, 8, 9 was decidedly less effective, most of the patches regrowing densely 

 clustered conidiophores. On leaves 6 and 10 both solutions had this same 

 almost non-fungicidal effect. 



As has been mentioned, at neither strength were the solutions 

 completelv fungicidal. Since the action was less marked at the higher 

 concentration of the solution, it seems clear that some new factor was 

 operative, perhaps that of a reduced spreading power. 



Comparison of Lime-sulphur Solvtions XII and XIII 

 (both with I % saponin). 



In Experiment 41 Solution XII, with 0-17 % polysulphide sulphur, 

 was fungicidal for nine out of the eleven leaves. The two leaves on 

 which the mildew lived and produced powdery patches of conidiophores 

 were mildewed over practically their whole surface at the time of 

 spraying. It is possible that under such conditions the inferior spreading 

 powers .of saponin did not ensure contact everywhere with the solution. 

 In Experiment 4-5 the solution, at the same concentration, was fungicidal 

 for seven leaves; on three leaves a few of the patches regrew a few 

 scattered conidiophores, and on one leaf (at the third node) some patches 

 regrew clustered conidiophores. 



With 0-23 % polysulphide sulphur both solutions proved completely 

 fungicidal. Used at this strength with 1 % saponin both these lime- 

 sulphur solutions leave no visible deposit on the sprayed parts, — a point 

 of considerable economic importance when such fruits as gooseberries 

 are sprayed. 



At the present time lime-sulphur solutions are invariably used in 

 this country as a "summer spray" (without the addition of saponin 

 or any other spreading agent) at a dilution of 1 in 30, the concentrated 

 solution having the specific gravity of 1-30. With such a commercial 

 brand as that used in the above experiments, such a dilution gives 

 0-77 % of polysulphide sulphur. 



If the result obtained in the above experiments (where a concentra- 

 tion of 0-23 % polysulphide sulphur proved fungicidal) holds good when 

 mildews on plants growing in the open are sprayed, it is obvious that 



