Leaching and sorption of neonicotinoid insecticides and fungicides from seed coatings

Journal of Environmental Science and Health - Part B Pesticides, Food Contaminants, and Agricultural Wastes
By: , and 

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Abstract

Seed coatings are a treatment used on a variety of crops to improve production and offer protection against pests and fungal outbreaks. The leaching of the active ingredients associated with the seed coatings and the sorption to soil was evaluated under laboratory conditions using commercially available corn and soybean seeds to study the fate and transport of these pesticides under controlled conditions. The active ingredients (AI) included one neonicotinoid insecticide (thiamethoxam) and five fungicides (azoxystrobin, fludioxonil, metalaxyl, sedaxane thiabendazole). An aqueous leaching experiment was conducted with treated corn and soybean seeds. Leaching potential was a function of solubility and seed type. The leaching of fludioxonil, was dependent on seed type with a shorter time to equilibrium on the corn compared to the soybean seeds. Sorption experiments with the treated seeds and a solution of the AIs were conducted using three different soil types. Sorption behavior was a function of soil organic matter as well as seed type. For most AIs, a negative relationship was observed between the aqueous concentration and the log Koc. Sorption to all soils tested was limited for the hydrophilic pesticides thiamethoxam and metalaxyl. However, partitioning for the more hydrophobic fungicides was dependent on both seed type and soil properties. The mobility of fludioxonil in the sorption experiment varied by seed type indicating that the adjuvants associated with the seed coating could potentially play a role in the environmental fate of fludioxonil. This is the first study to assess, under laboratory conditions, the fate of pesticides associated with seed coatings using commercially available treated seeds. This information can be used to understand how alterations in agricultural practices (e.g., increasing use of seed treatments) can impact the exposure (concentration and duration) and potential effects of these chemicals to aquatic and terrestrial organisms.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Leaching and sorption of neonicotinoid insecticides and fungicides from seed coatings
Series title Journal of Environmental Science and Health - Part B Pesticides, Food Contaminants, and Agricultural Wastes
DOI 10.1080/03601234.2017.1405619
Volume 53
Issue 3
Year Published 2018
Language English
Publisher Taylor & Francis
Contributing office(s) New Jersey Water Science Center, California Water Science Center
Description 8 p.
First page 176
Last page 183