Herbicidal properties of benzene and certain methyl derivatives

This paper reports some recent studies on the toxicity of benzene and several methyl derivatives for three plant species. Toxicity in both vapor and spray experiments increased in the order benzene, toluene, xylene, trimethylbenzenes; plant resistance in the order tomato, barley, carrot. The physical basis of the acute toxic action of these hydro-carbons is indicated by the narrow concentration range of toxicity, change in activity with different diluents, and correlation of toxicity with water solubility, water-oil partition coefficients, and boiling points. Benzenes are good fat solvents; the mechanism of acute toxicity probably involves disorganization of the outer plasma membrane of the cell, due to solvent action on the lipoid constituents. Partition phenomena determine concentration of hydrocarbon at point of action. Carrots showed relative resistance in all treatments. Basis of selectivity may lie in the character of the cell wall or of the outer plasma membrane.