29S Fnurficidal Properties of Certain Sjira/f-fiulds 



AitiiHotuinii hudrosulfhidc (coiitaininy 3-12 % sulphide aulphiir) compared 

 with Ammonium polysuiphide Solution XI {diluted to contain 0-038 % 

 sulphide sulphur ami 0-1 13 % poii/sulphide sulphur) (both Molutions 

 with 1 % soap). 



With ammoniuoi hydrosulphide there was at tirst a severe cliecking 

 action, so that on the fifth day after spraying seven of the leaves were 

 'still sterile, and on the three remaining leaves only. a very few conidio- 

 phores had been produced at the edges of the patches. By the ninth 

 day it was clear that that ammonium hydrosulphide was non-fungicidal 

 for at least some leaves; while Solution XI was everywhere fungicidal^. 

 The material on the whole was rather poor, which makes the non- 

 fungicidal action of the ammonium hydrosulphide the more remarkable. 

 On the 11 th day the leaves were classified as follows: 



Aniinoniiim hydrasulphiik' Solution XI 

 No. of leaf No. of leaf 



Fungicidal ... — 1^1" 



Non-fungicidal (several "powdery" patches) 2, 3. 7, 8, 'J, 11, 14 — 



Checked; clu.stered conicliophores from seve- 

 ral patches 1, l>, 10 — 



Severely checked; a very few eonidio])hores 



from a few patches (poor material) ... 4, 5 — 



Leaves discarded (injury) ... ... ... 12,13 — 



Solution. XI (auuuonium poli/sulphidc) compared u'ilh Solution. XII (lime- 

 sulphur) — both with 1 % saponin (Table 3). 



These solutions behaved very similarly. 



With 0-078 % polysulphide sulphur the two mixtures appeared to 

 be identical in action. This was shown by the fact that the four leaves 

 on which the patches were all killed by each solution were at the same 

 nodes on the same plants, as was also the case with the six leaves on 

 which many patches produced more or less clustered conidiophores 

 round their edges. 



With 0-113 % polysulphide sulphur the action of the two solutions, 

 although very similar, was slightly more fungicidal in the case of the 

 ammonium sulphide, as the following details show. On leaf 1 the 

 action of the two solutions was identical; on leaves 2, 3, 4, 5 the am- 

 ^iionium sulphide solution proved almost fungicidal (i.e., most of the 



1 Four leaves, Nos. 11-14, oppo.site to those sprayed with the ammonium hydro- 

 sulphide, were left unsprayed as "controls." On the fifth day only on one leaf. No. 14, 

 were the patches powdery, on the remaining three leaves the mildew appeared to be 

 dying away. 



