Title: Development of mathematical models for the uptake of agrichemicals through plant leaves; influence of adjuvants on plant and product interactions
Industry Partner: Plant Protection Chemistry NZ Ltd. (PPCNZ)
The uptake of systemic pesticides in weeds is crucial for biological efficacy of the pesticide spray. For example, it has been demonstrated recently that the bioefficacy of the herbicide glyphosate is 30-50% related to retention (the overall capture by plants of spray droplets after loss due to run-off) and 50-70% related to uptake. However, the knowledge of the mechanisms of pesticide uptake into plant foliage (and models for this) is much less advanced than for retention.
There is a need to develop process-driven, mathematical models for the diffusion of agrichemicals into plant leaves. These models will be used to gain a better understanding of chemical uptake by plants and hence aid in the development of improved agrichemical spray formulations leading to the reduction in the amount of active ingredient required. Less chemical use leads to improved efficiencies in crop production and lower residues in crops, enhancing market access for growers and improving the environmental sustainability of essential pesticide use in food production.
To increase foliar uptake, surfactant adjuvants are added to pesticides. The lipophilicity of the active ingredient and the surfactant, as well as their concentrations also affect active ingredient uptake and would need to be accounted for in models for uptake into plant foliage. Mathematical models that have enough of the physical and chemical mechanisms incorporated into them to be realistic but are not so detailed that they contain numerous parameters that are impossible to resolve, are precisely what is required from this project.