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Factors in testing fungicides against powdery mildews. II. Tests against oat powdery mildew in the greenhouse
Author(s) -
ZARACOVITIS C.
Publication year - 1965
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/j.1744-7348.1965.tb07942.x
Subject(s) - powdery mildew , fungicide , biology , captan , lauric acid , triadimefon , fatty alcohol , inoculation , alcohol , acetone , fatty acid , horticulture , food science , biochemistry
SUMMARY Some factors affecting fungicidal efficiency were studied during greenhouse tests with Erysiphe graminis on oat seedlings. In a comparison of non‐ionic, cationic and anionic surface‐active compounds, for formulating chemicals for testing, 'Ethylan CP' at 0·0025% in demineralized water at 30°C., plus 1–2% of acetone or ethyl alcohol, was found satisfactory and was used throughout later work. Studies of the effect of time of eradicant application on the efficacy of 'dinocap', lauric acid and a captan analogue demonstrated that these chemicals applied 24 hr. after inoculation were significantly less effective than at 48 and 72 hr. Fungitoxicity trials using a homologous series of n‐alkyl fatty acids and related compounds showed that lauric acid applied at 2·5 X 10 ‐4 m as an eradicant 48 hr. after inoculation gave 99% reduction of infection. Of the related compounds, n‐alkylamines with 11–13 carbon atoms equalled the acids in activity, but the amides and fatty alcohols at the same molar concentration were inactive.