Abstract14C‐Methylene labelled phorate was added to nutrient solutions supplying the roots of young broad bean plants and after 24 h absorption, fresh nutrient was substituted. The radiolabel accumulated at the leaf margins was initially associated with solvent‐soluble toxic metabolites. Radiolabel extracted from foliage which developed after the treatment was mainly in water‐soluble form. The maximum concentration of toxic material occurred in the marginal areas of the leaves after 5 or 6 days and in the central portions after 2 days. The concentrations declined to half of their peak values in 4–6 days from leaf‐margin tissue and in 2 days from the central tissues. Water‐soluble label did not accumulate to any significant extent. Most was found in the marginal areas but concentrations built up slowly reaching a maximum after about 2 weeks, declining slowly
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