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The behaviour of systemic insecticides in plants: A survey of results obtained with 32 P‐labelled schradan and demeton‐s
Author(s) -
Thomas W. D. E.
Publication year - 1956
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740070901
Subject(s) - coleus , absorption (acoustics) , phloem , botany , chromosomal translocation , biology , horticulture , chemistry , materials science , biochemistry , composite material , gene
Experiments on the behaviour under glasshouse conditions of schradan and demeton‐S applied to different species of plants are reviewed. Following application of schradan to leaves, some was absorbed and some evaporated. Absorption occurred both in light and darkness but higher temperatures accelerated initial absorption. Whilst the two surfaces of broad bean and Coleus leaves were equally absorptive, the lower surface of apple and chrysanthemum leaves absorbed more than their upper surface. Application of demeton‐S to leaves was followed by three processes—evaporation, change into less volatile, toxic derivatives, and absorption, and the chemical was effectively removed from the leaf surface within a few hours. The products derived from demeton‐S were also absorbed but at a slower rate. The evaporation of demeton‐S gave rise to a fumigant effect. Translocation of schradan from treated leaves to other parts of the plant occurred, mainly in an upward direction and in amounts sufficient to kill aphids. Schradan was also found in the nectar of borage and mustard flowers following leaf application before the flowers had opened. The schradan appeared to be translocated in the phloem. Translocation from leaves treated with demeton‐S was never sufficient to kill aphids feeding elsewhere on the plant, and no unchanged demeton‐S and only small amounts of its toxic derivatives were found in untreated leaves or nectar. Species differences were found in the rate of breakdown of schradan after absorption from leaves and in the relative rate of breakdown of schradan in treated leaves and in those receiving schradan by translocation. The primary derivatives of demeton‐S were retained for several weeks, especially within treated leaves. The breakdown rates of both schradan and demeton‐S slowed down towards the end of the growing season. Following root application to broad beans in sand or soil, unchanged demeton‐S was absorbed and detected in the shoot tip where concentrations of demeton‐S and its primary derivatives were present in amounts sufficient to kill Aphis fabae. Movement in xylem following root application seems to occur freely.