Performance of tank-mix partners with isoxaflutole across the Cotton Belt

Abstract

BASF Corporation has developed P-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor-resistant cotton and soybean that will allow growers to use isoxaflutole in future weed management programs. In 2019 and 2020, a multi-state research project was conducted non-crop to examine weed control following isoxaflutole applied preemergence alone and with a number of tank mix partners at high and low labeled rates. At 28 DAT, Palmer amaranth was controlled ≥95% at 6 of 7 locations with isoxaflutole plus the high rate of diuron or fluridone. These same combinations provided the greatest control 42 DAT at 4 of 7 locations. Where large crabgrass was present, isoxaflutole plus the high rate of diuron, fluridone, pendimethalin, or S-metolachlor or isoxaflutole plus the low rate of fluometuron controlled large crabgrass ≥95% in 2 of 3 locations 28 DAT. In 2 of 3 locations, isoxaflutole plus the high rate of pendimethalin or S-metolachlor improved large crabgrass control 42 DAT when compared to isoxaflutole alone. At 21 DAT, morningglory was controlled ≥95% at all locations with isoxaflutole plus the high rate of diuron and at 3 of 4 locations with isoxaflutole plus the high rate of fluometuron. At 42 DAT at all locations, isoxaflutole plus diuron or fluridone and isoxaflutole plus the high rate of fluometuron improved morningglory control compared to isoxaflutole alone. These results suggest that isoxaflutole applied preemergence alone or in tank mixture is efficacious on a number of cross-spectrum annual weeds in cotton and extended weed control may be achieved when isoxaflutole is tank mixed with a number of soil residual herbicides.

HPPD-resistant cotton response to isoxaflutole applied preemergence and postemergence

“…It is important to note, like 2019, IFT alone caused 0% cotton injury 9 to 14 DA PRE. Cotton injury observed in this study is similar to that observed by Cahoon et al (2015a) and Foster (2021). Previous research carried out in North Carolina found that cotton was injured ≤3% 18 to 27 DA PRE by acetochlor, diuron, fomesafen, and fluometuron and two- and three-way combinations of the residual herbicides (Cahoon et al 2015a).…”

“…IFT, applied alone or in combination with other herbicides, caused minimal cotton injury, thus demonstrating potential for safe use at either timing. These findings are further reinforced by research conducted in Arkansas and Texas, which also reported no decrease in cotton stand, minimal injury, and no reductions in lint yield from IFT applied PRE or EPOST when used alone or combined with other herbicides (Fleming et al 2021; Foster 2021). Additionally, the experimental cotton cultivar demonstrated tolerance to commonly used cotton herbicides PRE and POST.…”

“…EPOST applications of VLCFA inhibitors can cause cotton injury, but even in cases in which moderate or severe early season injury has been documented, cotton lint yield remains unaffected (Cahoon et al 2014; Eure et al 2013; Everman et al 2007, 2009; Inman et al 2014; Samples 2020). In Texas, Foster (2021) observed similar response of HPPD-resistant cotton to EPOST applications of dimethenamid -P + glufosinate, which resulted in 6% to 10% cotton injury 14 DA EPOST across 4-site years. However, Foster (2021) reported greater cotton injury following IFT + glufosinate (6% to 9%) applied EPOST compared to 2% to 4% injury from the combination in this study.…”

“…In Texas, Foster (2021) observed similar response of HPPD-resistant cotton to EPOST applications of dimethenamid -P + glufosinate, which resulted in 6% to 10% cotton injury 14 DA EPOST across 4-site years. However, Foster (2021) reported greater cotton injury following IFT + glufosinate (6% to 9%) applied EPOST compared to 2% to 4% injury from the combination in this study.…”

“…Previous research carried out in North Carolina found that cotton was injured ≤3% 18 to 27 DA PRE by acetochlor, diuron, fomesafen, and fluometuron and two- and three-way combinations of the residual herbicides (Cahoon et al 2015a). Foster (2021) evaluated HPPD-resistant cotton in Texas and reported 1% injury 14 DA PRE from IFT + fluometuron and IFT + pendimethalin.…”