Imazapic, imazamox, imazaquin, and imazethapyr are herbicides commonly used on corn and soybean plants in the Midwest. In previous studies of imidazolinone herbicides, photolysis has been shown to be a major pathway of degradation in the environment. The purpose of this study was to determine the rate at which each herbicide degraded under different conditions and to propose photoproducts of the degradation. Two different systems were used for study: irradiation of the herbicides in aqueous solution and the epicuticular waxes of corn and soybean leaves.  Using ultraviolet light, these herbicides were irradiated in a series of solutions with different pH values, in solutions at pH 7 with varying amounts of natural organic matter (NOM), or after being deposited on epicuticular wax layers. The rates of degradation were analyzed using an HPLC.  Photoproducts were identified using a combination of QTOF-LC-MS and LC-MS-MS. Future work will include obtaining more data on the corn and soybean waxes, identifying photoproduct pathways, and observing how the herbicides degrade when analyzed on intact corn and soybean plant leaves.

Photodegradation of imidazolinone herbicides and pesticides in aqueous solution and on plant surfaces

248th National Meeting (2014)

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