Abstract
Field and greenhouse experiments were conducted to characterize the response of a waterhemp population from McLean County, IL to foliar-applied 4-hydroxyphenylpyruvate dioxygenase (HPPD) –inhibiting herbicides and determine the population's sensitivity to herbicides from other site-of-action groups. In the field, 10 to 15–cm-tall waterhemp treated with mesotrione at 105 g ai ha−1, tembotrione at 92 g ai ha−1, or topromezone at 18 g ai ha−1had significantly greater biomass (≥ 10%) 14 d after treatment (DAT) than waterhemp harvested the day of herbicide application, indicating growth had occurred following herbicide application. Waterhemp growth stage at the time of herbicide application influenced control. Mesotrione applied at 105 g ha−1alone or combined with atrazine at 560 g ai ha−1provided significantly greater waterhemp control (≥ 66%) when applied to small waterhemp plants (2 to 5 cm tall) compared with applications made to plants 5 to 10 or 10 to 15 cm tall. Glyphosate, glufosinate, fomesafen, lactofen, or acifluorfen provided greater waterhemp control (≥ 68%) 7 and 14 DAT than mesotrione, dicamba, or 2,4-D. Control of this population with atrazine, chlorimuron, and imazethapyr did not exceed 12%. Results of a greenhouse experiment with waterhemp plants grown from field-collected seed were similar to field data, and confirm the McLean County population was poorly controlled with HPPD, photosystem II, and acetolactate synthase inhibitors.
Highlights
Field and greenhouse experiments were conducted to characterize the response of a waterhemp population from McLean County, IL to foliar-applied 4-hydroxyphenylpyruvate dioxygenase (HPPD) –inhibiting herbicides and determine the population’s sensitivity to herbicides from other site-of-action groups
Plantas de A. tuberculatus de 10 a 15 cm de altura, tratadas con mesotrione a 105 g ai haÀ1, tembotrione a 92 g ai haÀ1, o topramezone a 18 g ai haÀ1, tuvieron una biomasa significativamente mayor (!10%) 14 d despues del tratamiento (DAT) que A. tuberculatus cosechado el dıa de la aplicacion del herbicida, indicando que hubo crecimiento despues de la aplicacion del herbicida
In greenhouse and laboratory research, waterhemp grown from seed collected at the McLean County, IL location demonstrated resistance to foliar-applied mesotrione, tembotrione, and topramezone at rates of 105, 92, and 18 g ai haÀ1, respectively, and resistance to the photosystem II (PSII) inhibitor atrazine (Hausman et al 2011; Ma et al 2013)
Summary
Field and greenhouse experiments were conducted to characterize the response of a waterhemp population from McLean County, IL to foliar-applied 4-hydroxyphenylpyruvate dioxygenase (HPPD) –inhibiting herbicides and determine the population’s sensitivity to herbicides from other site-of-action groups. Nomenclature: Acifluorfen; atrazine; chlorimuron; dicamba; fomesafen; glufosinate; glyphosate; imazethapyr; lactofen; mesotrione; tembotrione; topramezone; 2,4-D; waterhemp, Amaranthus tuberculatus (Moq.) Sauer var. In greenhouse and laboratory research, waterhemp grown from seed collected at the McLean County, IL location demonstrated resistance to foliar-applied mesotrione, tembotrione, and topramezone at rates of 105, 92, and 18 g ai haÀ1, respectively, and resistance to the PSII inhibitor atrazine (Hausman et al 2011; Ma et al 2013). Additional greenhouse research revealed the Illinois waterhemp population demonstrated a 10 to 35–fold level of resistance to the HPPD inhibitor mesotrione (Hausman et al 2011). McMullan and Green (2011) reported similar greenhouse results with the Iowa waterhemp population, which demonstrated an 8-fold level of resistance to mesotrione as well as resistance to atrazine (10fold) and thifensulfuron (28-fold)
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