Abstract
IT is an essential prerequisite of a fungicidal spray that it should not itself cause damage on the plants to which it is applied. This is, unfortunately, not always the case, for lime-sulphur sometimes causes early leaf-drop on the apples Cox's Orange Pippin and Worcester Pearmain. M. H. Moore has shown (J. Pom. and Hort. Sci., 23, 3 and 4, Dec. 1947) that this damage can be greatly reduced by adding 4 Ib. of ferrous sulphate crystals to every gallon of lime-sulphur concentrate before dilution. Sprays against apple scab were made according to the usual schedule. The relative effects of calcium arsenate and lead arsenate separately mixed with lime sulphur as post-blossom sprays were also estimated. Calcium arsenate powder proved more toxic to the apple leaves than lead arsenate paste of much less arsenic oxide equivalent. The inclusion of ferrous sulphate in the mixtures, however, reduced the leaf-drop ; but did not markedly prevent fruit-drop. Zinc sulphate provided no suitable alternative to ferrous sulphate ; it was highly phytotoxic.
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Mitigation of Spray Injury. Nature 162, 408–409 (1948). https://doi.org/10.1038/162408e0
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DOI: https://doi.org/10.1038/162408e0