J. V. Eyre and E. 8. Salmon 477 



proved a jjowerful fungicide against the Apple '"scab" fungus {Fusi- 

 cladiinn). An "iron sulphide spray^" has been used by W. H. Volck^ 

 with success in field experiments against the Apple powdery mildew. 

 M. B. Waite reports^ the successful use of an "iron sulphide mixture" 

 (to which arsenate of lead was added) against fungous diseases of the 

 Apple. The striking results obtained in our experiments with a mixture 

 of iron sulphide and soft soap are recorded below at p. 501. 



Methods. 



The plants used in testing the fungicidal value of the various solutions 

 were 1- or 2-year old seedlings of the Hop (Humulus Lupidus Linn.) 

 bearing the "powdery mildew" Sphaerotheca Huiimli (DC.) Burr. The 

 plants stood in an unheated greenhouse, kept as well ventilated as 

 possible. In a few exjjeriments in 1915 Gooseberry bushes in the 

 02:)en, bearing the American Gooseberry-mildew {S. mors-uvae (Schwein.) 

 Berk.), were used. 



The hop-plants used in the experiments were kept close together, 

 and under the conditions of culture became severely infected with 

 the hop-mildew. The spraying was done during the months of May, 

 June and July. The plant used for spraying was carefully selected 

 as bearing on a number of its leaves young and vigorously-growing 

 patclies of the mildew in its conidial stage. In order to make the 

 experiments as strictly comparable as possible only those patches of 

 mildew were used where the growth was so vigorous that the abundant 

 conidiophores had produced masses of ripe, free conidia*. On each 

 plant from 2 to 4 leaves, each bearing a large number (10-20) of 

 "powdery" patches, were sprayed (using a hand "atomiser") with 

 the solution, while the same number of leaves bearing exactly similar 

 patches were reserved as " controls." The solution was applied in the 

 finest spray with sufficient force and (quantity to wet thoroughhj all 

 the patches of mildew. The "control" leaf was always on the same 

 plant, and was usually the opposite leaf at the same node. In every 

 experiment made, the mildew on the control leaves continued to grow 

 and extend its patches; it is therefore unnecessary to mention the 



1 Tlie spray used is described by the author as beint; "a mixture of iron sulphide, 

 gypsum and precipitated sulphur." Arsenate of lead was added to it. The percentage 

 of iron sulphide in the various spray-fluids used was, apparently, from 0-2 % to 0-6 %. 



- Volck, W. H., in Better Fruit, p. 39 (1911). 



3 Waite, M B., U.S. Dept. Agric. Bureau of Plant Industry Circular, 58 (1910). 



* This stage is denoted by the term "powderj'" in the details of the experiments 

 given below at p. 480 and sqq. 



