Mechanistic basis for synergism of 2,4-D amine and metribuzin in <i>Avena sterilis</i>

Abstract

The combination of herbicides with different modes of action has been adopted not only to improve weed control but also to increase the environmental sustainability of plant-protection products. In this study, we showed a synergistic effect of the auxin herbicide 2,4-D amine with the PSII-inhibiting herbicide metribuzin to control the global grass weed wild oat (Avena sterilis) population and investigated the underlying mechanisms. Pretreatment with 2,4-D amine did not change the foliar absorption of metribuzin but did increase metribuzin translocation to the roots and new leaves, although enhancement of the metribuzin metabolism was also observed. Considering that the expression level of the target site psbA gene is significantly higher in leaves than in roots, increased metribuzin translocation to new leaves is likely the major cause of the observed synergism, even though enhanced metribuzin metabolism may offset the metribuzin efficacy. This is the first report on the synergistic mechanism between 2,4-D amine and metribuzin in weed control.

The Joint Action of Some Broadleaf Herbicides on Potato (Solanum tuberosum L.) Weeds and Photosynthetic Performance of Potato

“…The 14 C-halosulfuron translocation in treated leaves of corn (Zea mays L.) was 96% [31]. In contrast, the 14 C-metribuzin translocation was limited in wild oat (Avena Sterilis L.) [32].…”

“…The 14 C-halosulfuron translocation in treated leaves of (Zea mays L.) was 96% [31]. In contrast, the 14 C-metribuzin translocation was limit wild oat (Avena Sterilis L.) [32]. Choice of appropriate rates and tank-mix partner(s) is critical for weed control.…”

Herbicide mixtures: interactions and modeling

“…However, the mixture resulted in enhanced metribuzin translocation to the roots and new leaves. Since new leaves express high levels of the psbA gene to prepare this nascent tissue for photosynthesis, the synergism is most likely due to the increased metribuzin translocation to new leaves, even though enhanced metabolism may offset some of the effect (Han et al, 2020).…”

Biologically effective dose of pyraflufen-ethyl/2,4-D, applied preplant alone or mixed with metribuzin on glyphosate-resistant horseweed in soybean

“…All other interactions were additive (Table 4). Han et al (2020) found that sequential applications of 2,4-D amine followed by metribuzin caused a synergistic interaction with increased metribuzin movement to the newly developed leaves in wild oats [Avena sterilis (L.)]. In corn, the co-application of 2,4-D with atrazine, a photosystem II-inhibitor, resulted in a synergistic improvement in the control of prostrate knotweed [Polygonum aviculare (L.); Ludwig 1973].…”