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The fungicidal properties of certain spray-fluids. II

Published online by Cambridge University Press:  27 March 2009

J. Vargas Eyre ,
E. S. Salmon  and
L. K. Wormald
J. Vargas Eyre
Affiliation:
(Research Department, South-eastern Agricultural College, Wye, Kent.)
E. S. Salmon
Affiliation:
(Research Department, South-eastern Agricultural College, Wye, Kent.)
L. K. Wormald
Affiliation:
(Research Department, South-eastern Agricultural College, Wye, Kent.)
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Extract

1. The resistance of the hop-mildew (Sphaerotheca Humuli (DC.) Burr.) to polysulphide solutions varies according to its stage of development. The earliest stages after infection and antecedent to the production of conidiophores are the most resistant, requiring approximately a solution of double the concentration lethal for the “powdery” conidial stage. The “powdery” conidial stage occurring on young leaves is more resistant than the same stage on older leaves.

2. Conclusive proof has been obtained that with polysulphide solutions neither the total sulphur content nor the sulphide sulphur content gives an index of their fungicidal value.

3. The percentage of polysulphide sulphur in polysulphide solutions appears to be the factor determining their fungicidal value.

4. The fungicidal value of such solutions does not depend upon the nature of the polysulphides present.

Type
Research Article
Information
The Journal of Agricultural Science , Volume 9 , Issue 3 , September 1919 , pp. 283 - 307
Copyright
Copyright © Cambridge University Press 1919

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References

Page 283 note 1 Eyre, J. Vargas and Salmon, E. S., “The Fungicidal Properties of Certain Spray fluids,” Journ. Agric. Science, 7, 473–507 (1916).CrossRefGoogle Scholar

Page 283 note 2 Eyre, J. Vargas and Salmon, E. S., loc. cit., p. 477.Google Scholar

Page 287 note 1 Several of the solutions used were made according to the details given by Bloxam, . Vide “The Sulphides and Polysulphides of Ammonium,” Trans. Chem. Soc., 67, 1895, pp. 277–309.CrossRefGoogle Scholar

Page 288 note 1 The method used was that given by Bloxam, . Vide Trans. Chem. Soc., 1895, p. 289.Google Scholar

Page 294 note 1 In these experiments, as in all the following ones in which two solutions were compared with each other, the leaves sprayed with the two solutions were always at the same node.

Page 297 note 1 Sufficient force was used in this experiment practically to drench the leaves.

Page 298 note 1 Four leaves, Nos. 11–14, opposite to those sprayed with the ammonium hydrosulphide, 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.

Page 301 note 1 In an experiment on May 18, 1918, three leaves (at the 7, 8 and 9 nodes) bearing powdery patches were sprayed with 1% Chiswick soft soap. On the next day only a few of the patches showed less than normal vigour, and by the third day all the patches were as powdery as before spraying.