The effect of organophosphorus insecticidal sprays on the growth and phosphorus content of brussels sprouts

No evidence was found that the insecticides schradan or demeton directly increase the growth of plants. The dry weight of Brussels sprouts plants grown in soil supplying little phosphorus was unaffected by spraying six times with schradan or demeton, or with sodium phosphate solution supplying the same amount of phosphorus as the insecticides. The dry weight of larger plants grown in soil supplying more phosphorus was unaffected by spraying with demeton or inorganic phosphorus solutions; schradan spray decreased it in one experiment but not in the other. Spraying with schradan, or with the equivalent amount of phosphorus as sodium phosphate, in one experiment increased the phosphorus content of plants grown in soil supplying little phosphorus. With high phosphorus supply in the same experiment, sodium phosphate solution, but not schradan, increased phosphorus content of the plants slightly, but not significantly. Phosphorus content was not affected either by schradan sprays in the other experiment or by demeton sprays in both experiments.