Sweetpotato Tolerance and Palmer Amaranth Control with Metribuzin and Oryzalin

Abstract

Field studies were conducted in Clinton, NC in 2007 and 2009 to determine sweetpotato crop response and Palmer amaranth control with metribuzin and oryzalin. Treatments consisted of 140 and 202 g ai ha−1metribuzin applied immediately after transplanting [0 wk after transplanting (WAP)] or 2 WAP, 560 and 1121 g ha−1oryzalin 0 WAP, and tank mixes of metribuzin (140 or 202 g ha−1) and oryzalin (560 or 1,121 g ha−1) 0 WAP. At 2 WAP, metribuzin alone applied 0 WAP resulted in greater crop injury (33%) than oryzalin alone (1%), and the tank mix of metribuzin plus oryzalin resulted in greater crop injury (49%) than either herbicide applied alone. Greater crop injury occurred when metribuzin was applied at 202 g ha−1(54%) than 140 g ha−1(34%). Levels of injury were similar at 4 WAP (34, 8, and 52% for metribuzin, oryzalin, and the tank mix, respectively). At 4 WAP, injury from metribuzin was greater when it was applied 0 WAP (34%) compared to 2 WAP (18%). By 10 WAP, injury from metribuzin applied at 2 WAP was only 4%. At 4 WAP, Palmer amaranth control was excellent for all treatments and ≥98%. At 10 WAP, control among treatments ranged from 77% to 85%. Palmer amaranth control provided by metribuzin was similar for applications made 0 WAP (78%) and 2 WAP (77%). Oryzalin alone provided similar control (85%) to metribuzin alone 0 WAP, but greater control than the tank mix (77%). Neither metribuzin nor oryzalin rate differed in weed control provided at 10 WAP. Oryzalin 0 WAP and metribuzin 2 WAP provided no. 1 sweetpotato yields equivalent to the hand-weeded check. No. 1 yields of all other treatments were less than the hand-weeded check but greater than the weedy check.

Recent Discovery of Amaranthus palmeri S. Watson in Italy: Characterization of ALS-Resistant Populations and Sensitivity to Alternative Herbicides

“…The recommended field rates of glyphosate, metribuzin and metobromuron completely controlled the three ALS-resistant A. palmeri populations. Glyphosate and metribuzin are known to control A. palmeri [27,28], whereas little information is available on the efficacy of metobromuron applied alone. Our results show that all three herbicides should be considered valuable options to control these A. palmeri populations.…”

Improved herbicide selectivity in tomato by safening action of benoxacor and fenclorim

“…by up to 96% at 21 days after treatment (Bond et al 2006). Metribuzin, a photosystem II inhibitor, controls several broadleaf weeds, including up to 75% control of Palmer amaranth when applied PRE (Meyers et al 2017). Steele et al (2005), on the other hand, reported greater than 97% control of Palmer amaranth plants using pyroxasulfone PRE, whereas Geier et al (2006) reported 85% and 99% control of Palmer amaranth at rates of 125 to 332 g ha −1 , respectively.…”

Response of Sweetpotato to Oryzalin Application Rate and Timing

“…Overall, these results indicate that early-season sweetpotato injury following oryzalin application is temporary, and sweetpotato is able to recover from injury with no effect on yield when compared to a nontreated check, regardless of application rate and timing. Based on these results demonstrating crop tolerance and the findings of others (Glaze and Hall 1990;Gossett et al 1992;Meyers et al 2017) demonstrating efficacious weed control in sweetpotato production systems, oryzalin has the potential to be a useful herbicide in an overall weed management program. Nelson et al (1983) reported that herbicide placement with respect to the germinating seed and soil moisture content are important factors for oryzalin efficacy.…”

“…Both leaf distortion and stunting from all treatments was transient and no injury was reported later in the season at 10 and 14 WAP (data not shown). Similarly, Meyers et al (2017) reported less than 10% sweetpotato injury from oryzalin applied immediately after sweetpotato transplanting at 560 or 1,121 g ha -1 .…”

“…Glaze and Hall (1990) reported that oryzalin at 0.8 kg ha -1 did not injure 'Georgia Jet' sweetpotato and provided 69 to 95% weed control over 4 years depending upon environmental conditions and weed species present. Meyers et al (2017) reported that oryzalin applied immediately after sweetpotato transplanting at 560 or 1,121 g ha -1 resulted in less than 10% crop injury and ≥ 98% Palmer amaranth control until 4 wk after treatment. Crop injury was transient, and no.…”