Transcuticular Penetration of Foliar-Applied Pesticides — Its Analysis by a Logistic-Kinetic Penetration Model

New Perspectives on the Metabolism and Detoxification of Synthetic Compounds in Plants

“…Depending on their route of application, hydrophobic compounds will pass directly into leaf cells by passive diffusion through the waxy cuticle, whereas more polar compounds have the potential for systemic uptake and movement throughout the plant via transport in the phloem or xylem depending on their physical chemical characteristics (Watanabe 2002). In the case of systemic transport, xenobiotics will pass from the symplast or apoplast across the plasma membrane either by passive diffusion, or more rarely by active transport being mistaken for essential solutes (Watanabe 2002). In any cells, internalised xenobiotics then immediately pose a potential toxic threat to the cell by disrupting membrane integrity or metabolic pathways and must therefore be rapidly safely sequestered, extruded or detoxified through biotransformation (Fig.…”

Mechanisms of cuticular uptake of xenobiotics into living plants: 1. Influence of xenobiotic dose on the uptake of three model compounds applied in the absence and presence of surfactants into Chenopodium album, Hedera helix and Stephanotis floribunda leaves

“…The effective cuticular thickness ( lx ) can be greater than the apparent or measured thickness ( x ). Isolated cuticle studies have confirmed the factors involved5, 6 and recently an excellent overview has been written on the different models that have been used to study cuticular penetration 7…”

“…Fick's first law of diffusion as modified for plant cuticles in vitro (Eqn (4)) may not be appropriate for in vivo situations where the applied quantity is a finite dose (from a droplet deposit). Watanabe7 found that the models dealing with non‐equilibrium transcuticular penetration kinetics did not fully quantify all the kinetic parameters involved in penetration from a droplet, and he has recently developed a non‐steady state, non‐equilibrium model,7 termed ‘the logistic‐kinetic penetration model’.…”

Factors influencing the association between active ingredient and adjuvant in the leaf deposit of adjuvant‐containing suspoemulsion formulations

“…It is clear that in many cases deposits are heterogeneous, and this should be considered when interpreting uptake. Combining this knowledge of the deposit form and its effective uptake surface with newer uptake models39, 56 will help with understanding the effect of annuli on AI uptake in the presence of adjuvants. Here, both the distribution of the AI within the deposits and the distribution of the adjuvant(s) relative to the AI will be important.…”