490 Fungicidal Fropertics of Certain S/iriiji-l'liiidn 



Gooseberries. 1915. 



In one experiment two shoots of a Gooseberry bush in the open 

 infested with the American Gooseberry-mihlew (SpJiaerolhcca iitors-uvae) 

 in its "powdery" conidial stage were sprayed in July, witii respectively 

 a solution of "liver-of-sulphur" containing 0-13% sulphide-sulphur 

 and a solution of ammonium sulphide containing ()-13% sulphide- 

 sulphur, both solutions containing 1 % soft soap. On the 7th day 

 after spraying the shoots were examined; the "liver-of-sulphur" 

 solution had had no more effect on the mildew than water, the mildew 

 being now densely "powdery" with fresh conidiophorcs and conidia; 

 the mildew on the shoot sprayed with aininouium sulphide was entirely 

 sterile and obviously dying. No injury was caused to the foliage. 



Summary of Observations. IV. 



The experiments afford clear evidence that a 0-3 % solution of 

 "liver-of-sulphur" — which, as already observed^, is the strengtli wliicli 

 in this country has been generally recommended for use — is quite 

 inefficacious as a fungicide against Hop and Gooseberry mildews. The 

 patches are checked, more or less, for the first few days, but by about 

 the 3rd day a fresh growth of conidiophorcs has taken place and, by 

 the 5th to 8th day after spraying, the patches have become "powdery" 

 again. The worthlessness of the 0-3% solution of "liver-of-sulphur" 

 (containing 0-13 % sulphide-sidphur) as compared with solutions of 

 ammonium sulphide containing either 0-08 % or 0-16 % sulphide-sulphur 

 was shown clearly in those experiments with Hops (Nos. 3 and 1) where 

 mildewed leaves on the same plant were sprayed with the two solutions 

 and also in the case of the Gooseberries sprayed in the open. 



A solution containing 0-4 % of "liver-of-sulphur" (0-17 % suipliidc- 

 sulphur) without the addition of soft soap has no greater fungicidal 

 value than the 0-3 % solution ; with the addition of soft soap the patches 

 are checked, but they are not killed entirely and are able to produce 

 conidiophores by the 8th to 10th day. 



A solution containing 0-6% "liver-of-sulphur" (0-2G % sulphide- 

 sulphur) greatly checks the mildew, which may remain dormant 

 permanently or may produce a few tiny clusters of conidiophores. In 

 two experiments, however, where this solution was used with respectively 

 1 % and 0-5 % soft soap, the ]iatches of mildew after being greatly 



• See p 474. 



