CHARACTERIZING PESTICIDE AND SURFACTANT PENETRATION WITH ISOLATED PLANT CUTICLES

A survey is presented of the use of isolated leaf and fruit cuticles i n studying foliar penetration. Isolated cuticles, which represent the prime barrier to penetration, provide a physical system with which tra nsport studies can be conducted under well-defined and highly controll ed conditions while avoiding the physiological effects of biologically active compounds on the system. Most studies with isolated cuticles h ave focused on sorption, desorption and infinite-dose cuticular transp ort of compounds in aqueous systems. Partition coefficients can be cal culated for pesticides from sorption data, thereby yielding informatio n on the solubility of the compounds in the cuticle. Permeance and dif fusion coefficients can be calculated from cuticular transport studies . These transport parameters provide for a better understanding of the mechanisms of cuticular penetration. Further, they are useful in comp aring both the penetration characteristics of selected compounds and p ermeability of cuticles. Transport systems, using isolated cuticles, m ay be used to quantify the effects of spray additives on pesticide pen etration. A finite-dose system is described that may be useful in stud ying spray droplet/deposit interactions with the cuticle and, concurre ntly, following transcuticular penetration from droplets/deposits on t he surface. These systems may prove useful in optimizing spray formula tions and spray parameters, leading to more efficient pesticide develo pment and application.