Cuticular Wax Solubility and Leaf-Cell Membrane Permeability of Petroleum Solvents

Abstract

Information on petroleum solvent interaction with cuticular wax and with leaf-cell membranes may be useful in selecting the most effective solvents for pesticide formulation. Experiments were conducted with corn and green foxtail to determine petroleum solvent recoil from cuticular leaf wax, relative solvency for cuticular wax, leaf-cell membrane permeability as influenced by petroleum solvents, and fluazifop-P absorption, translocation and phytotoxicity when applied with various petroleum solvents. The solvent recoil test procedure was not reproducible. The relative solvency of petroleum solvents for cuticular leaf wax tended to be similar for both corn and green foxtail. Aromatic 100, Aromatic 200, EXXSOL D 80, NORPAR 15, and VARSOL 1 had greater solvency than ISOPAR L, ISOPAR M, ISOPAR V, ORCHEX 796, and distilled water for leaf wax. Correlations based on solvent structure are made. Solvency for cuticular wax correlated positively with leaf-cell membrane permeability. Both solvency for leaf wax and leaf-cell permeability correlated positively with solvent phytotoxicity. Fluazifop-P did not affect petroleum solvent phytotoxicity. Fluazifop-P had a negligible affect on petroleum solvent solubility for cuticular leaf wax but did reduce solvent volatility. Absorption and translocation of 14C-fluazifop in both corn and green foxtail were not greatly affected by the solvents tested. The solvent which enhanced fluazifop-P phytotoxicity the most was different for corn and green foxtail. Solvents tested differed in relative wax solubility and in their affect on leaf-cell membrane permeability, but no obvious relationship occurred among these factors and the absorption, translocation and phytotoxicity of fluazifop-P.