Physiological basis for tolerance of corn hybrids to foramsulfuron

Abstract

Foramsulfuron (AE F130360) is a sulfonylurea herbicide for postemergence control of grasses and some broadleaf weeds in corn. Greenhouse and laboratory experiments were conducted to determine the physiological basis for differential tolerance of corn hybrids to foramsulfuron. Differences in corn tolerance were quantified by determining the herbicide rate required to cause injury and reduce corn height by 15% (GR15). Seven hybrids were screened in the greenhouse where GR15 values indicated that the some of the corn hybrids were sensitive to foramsulfuron. All but one of these hybrids exhibited an increase in tolerance when the safener, isoxadifen-ethyl, was applied with foramsulfuron. Experiments using 14C-foramsulfuron were conducted to determine whether isoxadifen-ethyl affected foramsulfuron absorption, translocation, and metabolism in two of the corn hybrids. There was no difference in absorption between a sensitive hybrid Novartis 58D1 and a more tolerant hybrid Novartis 59Q9, but the addition of isoxadifen-ethyl increased foramsulfuron absorption in both hybrids 24 h after treatment. Less than 1 and 3% of the 14C-foramsulfuron was translocated to plant portions above and below the treated leaf, respectively. Differences in hybrid tolerance were primarily due to differential herbicide metabolism. Foramsulfuron metabolism, with and without isoxadifen-ethyl, was similar at 4 h after treatment for both the sensitive and tolerant hybrids. However, by 24 h after treatment the more tolerant hybrid metabolized foramsulfuron to more polar compounds to a greater degree than the sensitive hybrid.

Tolerance of Maize (<i>Zea mays</i> L.) and Soybean [<i>Glycine max</i> (L.) Merr.] to Late Applications of Postemergence Herbicides

“…Conversely, up to 16% injury 3 DAT has been found in maize treated with twice the labeled dose of foramsulfuron and 23% injury 7 DAT for maize treated with twice the dose of dicamba/diflufenzopyr [10]. Maize tolerance to foramsulfuron can vary considerably by application timing and maize hybrid [20] [21]. In the current study, the visible injury was transient with reduced injury observed at 21, 28, and 56 DAT.…”

Selectivity of Iodosulfuron-Methyl to Oat Cultivars

“…Direct methods involve chromatography to evaluate the decomposition of the herbicide and/or the formation of the metabolites (Hosseini et al, 2011;Yu and Powles, 2014). Indirect methods may involve the use of inhibitors of herbicide detoxification, such as malathion and chlorpyrifos (Kaspar et al, 2011;Beckie et al, 2012), or the use of stimulators of herbicide metabolization, also called crop safener (Bunting et al, 2004).…”

Commercial Safened ALS‐herbicide Formulation Effects on ALS‐sensitive Field Corn Hybrids

“…In 2002, the crop safener isoxadifen was released in a formulation with foramsulfuron. Studies have shown that the addition of isoxadifen to foramsulfuron, nicosulfuron, and rimsulfuron containing formulations successfully reduced corn phytotoxicity (Bunting et al, 2004; Effertz et al, 2001). Isoxadifen increases the concentration of cytochrome P450 enzymes in the corn plant.…”