Confirmation and Control of HPPD-Inhibiting Herbicide–Resistant Waterhemp (Amaranthus tuberculatus) in Nebraska

Abstract

Field and greenhouse experiments were conducted in Nebraska to (1) confirm the 4-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting resistant-waterhemp biotype (HPPD-RW) by quantifying the resistance levels in dose-response studies, and (2) to evaluate efficacy of PRE-only, POST-only, and PRE followed by POST herbicide programs for control of HPPD-RW in corn. Greenhouse dose-response studies confirmed that the suspected waterhemp biotype in Nebraska has evolved resistance to HPPD-inhibiting herbicides with a 2-to 18-fold resistance depending upon the type of HPPD-inhibiting herbicide being sprayed. Under field conditions, at 56 d after treatment, ≥90% control of the HPPD-RW was achieved with PRE-applied mesotrione/atrazine/ S-metolachlor + acetochlor, pyroxasulfone (180 and 270 g ai ha −1 ), pyroxasulfone/fluthiacet-methyl/ atrazine, and pyroxasulfone + saflufenacil + atrazine. Among POST-only herbicide programs, glyphosate, a premix of mesotrione/atrazine tank-mixed with diflufenzopyr/dicamba, or metribuzin, or glufosinate provided ≥92% HPPD-RW control. Herbicide combinations of different effective sites of action in mixtures provided ≥86% HPPD-RW control in PRE followed by POST herbicide programs. It is concluded that the suspected waterhemp biotype is resistant to HPPD-inhibiting herbicides and alternative herbicide programs are available for effective control in corn. The occurrence of HPPD-RW in Nebraska is significant because it limits the effectiveness of HPPD-inhibiting herbicides. Nomenclature: Acetochlor, atrazine, glyphosate, clopyralid, dicamba, diflufenzopyr, dimethenamid-P, flumetsulam, fluthiacet-methyl, glufosinate, isoxaflutole, mesotrione, metribuzin, pyroxasulfone S-metolachlor, saflufenacil, rimsulfuron, tembotrione, thiencarbazone-methyl, topramezone, waterhemp, Amaranthus tuberculatus (Moq.) Sauer, corn, Zea mays L. Key words: 4-hydroxyphenylpyruvate dioxygenase, pigment inhibitors, PRE, POST, triketone, weed management, weed resistance. Se realizaron experimentos de campo y de invernadero en Nebraska para (1) confirmar un biotipo de Amaranthus tuberculatus resistente a inhibidores de 4-hydroxyphenylpyruvate dioxygenase (HPPD) (HPPD-RW) cuantificando el nivel de resistencia con estudios de respuesta a dosis, y (2) evaluar la eficacia de programas de herbicidas para el control de HPPD-RW en maíz con sólo herbicidas PRE, sólo POST, y herbicidas PRE seguidos por POST. Los estudios de respuesta a dosis en invernadero confirmaron que el biotipo de A. tuberculatus en Nebraska ha evolucionado resistencia a herbicidas inhibidores de HPPD con 2 a 18 veces mayor resistencia dependiendo del tipo de herbicida inhibidor de HPPD que se aplicó. Bajo condiciones de campo, a 56 d después del tratamiento, se alcanzó ≥90% de control de HPPD RW con aplicaciones PRE de mesotrione/ atrazine/S-metolachlor + acetochlor, pyroxasulfone (180 y 270 g ai ha), pyroxasulfone/fluthiacet-methyl/atrazine, y pyroxasulfone + saflufenacil + atrazine. Entre los programas de herbicidas con sólo POST, glyphosate, una premezcla d...

Reversing resistance to tembotrione in an Amaranthus tuberculatus (var. rudis) population from Nebraska, USA with cytochrome P450 inhibitors

“…In the HPPD‐S, the H 50 and H 80 were 26 and 43 HAT, respectively (Table ). The smaller difference between HPPD‐R and HPPD‐S tembotrione metabolism is likely due to the moderate resistance level to tembotrione (6×), as demonstrated in previous research . Nonetheless, there was a strong synergistic effect of P450 inhibitors on the efficacy of tembotrione on the HPPD‐R population.…”

“…A field experiment was conducted in 2014 and 2016 at a Platte County field location near Columbus, NE, USA, where the HPPD‐R was reported . The soil type at the study location was a silty clay loam (12% sand, 60% silt, 28% clay) with 3.3% organic matter and a pH of 6.8.…”

“…A population of A. tuberculatus (HPPD‐R) with resistance to POST application of three HPPD‐inhibitor herbicides (mesotrione, tembotrione, and topramezone) was reported in a seed corn/soybean rotation field in northeast Nebraska . This population was highly resistant to mesotrione (18×), followed by (fb) tembotrione (6×), and topramezone (2×).…”

Evolution of resistance to HPPD‐inhibiting herbicides in a wild radish population via enhanced herbicide metabolism

“…Noticeably, this Palmer amaranth population had never been treated with HPPD inhibitors, but had a long history of ALS and PSII herbicide selection. HPPD‐inhibiting herbicide resistant Amaranthus populations have been reported in Iowa, Nebraska and Arkansas . Mechanistic studies have revealed that the predominant mechanism for HPPD‐inhibiting herbicide resistance in both Amaranthus species is enhanced herbicide metabolism .…”

“…Resistance to HPPD‐inhibiting herbicides has thus far only been reported in North America in waterhemp ( Amaranthus tuberculatus ) and Palmer amaranth ( Amaranthus palmeri ) . Among these resistant populations, most of them have been selected by HPPD‐inhibiting herbicides, with the exception of a Palmer amaranth population .…”