5U(j Fanijlcidal I'ropcrtivs of Certain Sprtiji-Fltiidfi 



compare Expcrs. 1 and 2) would d(']M)sit ()-178grm. of sulphur; and 

 100 c.c. of the yellow annnoniutn sulj)hide spray-fluid (containing 

 0-13% sulphide-sulphur: compare Expers. 9 and 10. p. 194) would 

 deposit 0-160 grm. of sulphur. 



This experiment was repeated three times and closely similar 

 results were obtained in each case showing that the amount of sulphur 

 actually deposited from these two kinds of alkaline sulphide solutions 

 is not widely different. It would seem therefore that a larger deposition 

 of sulphur occurred in the case of our Expers. 1 and 2 with ammonium 

 hydrosulphide than in Expers. 9 and 10, p. 494 with yellow ammonium 

 sulphide. In view of the considerable interest attaching to this part 

 of the subject, it is proposed to repeat and extend these experiments 

 during the coming season. 



From the results so far obtained the conclusion is reached that 

 yellow amnioni\un sulphide is valuable as a fungicide because of the 

 polysulphides contained in solution and that these probably act as such 

 and not by virtue of sulphur which is deposited. It is thought that 

 when a solution of ammonium hydrosulphide is allowed to evaporate 

 in the air the oxidation which takes place does not largely lead to 

 the formation of polysulphides but mainly to the direct deposition of 

 sulphur. 



General Su.mm.\ky .vxd Conclusions. 



1. Solutions of such substances as '"liver-of-sulphur' and 

 ammonium sulphide w^hen used against the "powdery mildews" (Erysi- 

 phuceae) in the actively-growing conidial stage recjuire the addition of 

 some substance such as soft soap in order to increase their wetting 

 properties and so secure complete fungicidal action. 



2. Solutions of "liver-of-sulphur" of the strength recommended 

 by authors generally (0-2% to 0-4 %) for use against the "powdery 

 mildews" are not fungicidal against the growing mycelium. When 

 the concentration is increased to 0'6 % or 0-8 % this substance begins to 

 be fungicidal. 



3. A solution of yellow ammonium sulphide has proved to be 

 completely efficacious against the Hop-mildew (in the greenhouse) and 

 the American Gooseberry-mildew (in the open). The use of this material 

 has the distinct advantage that, unlike lime-sulphur, it leaves no visible 

 deposit and does not therefore disfigure the fruit. Solutions of definite 

 fungicidal strength have caused no "scorching" injury (o the foliage 

 of the Hop or Gooseberry. 



