Measuring Leaf Penetration and Volatilization of Chlorothalonil and Epoxiconazole Applied on Wheat Leaves in a Laboratory-Scale Experiment

Abstract

Estimation of pesticide volatilization from plants is difficult because of our poor understanding of foliar penetration by pesticides, which governs the amount of pesticide available for volatilization from the leaf surface. The description of foliar penetration is still incomplete because experimental measurements of this complex process are difficult. In this study, the dynamics of leaf penetration of C-chlorothalonil and C-epoxiconazole applied to wheat leaves were measured in a volatilization chamber, which allowed us to simultaneously measure pesticide volatilization. Fungicide penetration into leaves was characterized using a well-defined sequential extraction procedure distinguishing pesticide fractions residing at different foliar compartments; this enabled us to accurately measure the penetration rate constant into the leaves. The effect of pesticide formulation was also examined by comparing formulated and pure epoxiconazole. We observed a strong effect of formulation on leaf penetration in the case of a systemic product. Furthermore, the penetration rate constant of formulated epoxiconazole was almost three times that of pure epoxiconazole (0.47 ± 0.20 and 0.17 ± 0.07, respectively). Our experimental results showed high recovery rates of the radioactivity applied within the range of 90.5 to 105.2%. Moreover, our results confirm that pesticide physicochemical properties are key factors in understanding leaf penetration of pesticide and its volatilization. This study provides important and useful parameters for mechanistic models describing volatilization of fungicides applied to plants, which are scarce in the literature.

Insights into the Relationships Between Herbicide Activities, Molecular Structure and Membrane Interaction of Cinnamon and Citronella Essential Oils Components

“…To verify that, EO emulsions, CitA, CitO, and CIN effectively penetrate the leaves and evaluate whether any biological conversion occurs during the test period, the following experimentation was undertaken, adapted from Lichiheb et al [51].…”

Heterogeneous atmospheric degradation of pesticides by ozone: Influence of relative humidity and particle type

“…Atmospheric pesticide contamination was observed in urban and rural areas with concentration levels from some picogram per cubic meter (pg m -3 ) to several nanogram per cubic meter (µg m -3 ) (Coscollà et al, 2013(Coscollà et al, , 2014Estellano et al, 2015;Zivan et al, 2016Zivan et al, , 2017. This contamination can be due to spray drift during pesticide applications (about 15 to 40%;Sinfort et al, 2009;Yates et al, 2015;Zivan et al, 2016Zivan et al, , 2017, post-application volatilization from treated plants (Zivan et al, 2016(Zivan et al, ,2017, soil (White et al, 2006) or aquatic surfaces (Luo et al, 2012) (about 0.1 to several dozen %; Lichiheb et al, 2015), and wind erosion (Glotfelty et al, 1989).…”

The Effects of Formulation on Imidacloprid Dissipation in Grapes and Vine Leaves and on Required Pre-Harvest Intervals under Lebanese Climatic Conditions

“…Furthermore, Lichiheb et al [ 23 ] and Fernández and Eichert [ 24 ] mentioned that leaf cuticle (permeability of leaf surface) and pesticide lipophilicity are two of the main factors influencing pesticide penetration in plants. Possingham et al [ 25 ] studied wax structure and composition of leaves and fruit of Vitis vinifera and found a “considerable qualitative difference between the waxes of leaves and fruits”, where grapes’ cuticular wax consisted of a “hard” wax component (70%); i.e., oleanolic acid; and a “soft” wax component, i.e., mixture of long chain acid, alcohols, aldehydes, ester and hydrocarbons; meanwhile, leaves had only the “soft” fraction.…”