Bromoxynil, Prometryn, Pyrithiobac, and MSMA Weed Management Systems for Bromoxynil-Resistant Cotton (Gossypium hirsutum)¹

Abstract

Field studies were conducted at two locations in North Carolina in 1999 and 2000 to evaluate weed and bromoxynil-resistant cotton response to bromoxynil, pyrithiobac, and MSMA applied early postemergence (EPOST), alone or mixtures in all combinations (two way and three way), and to prometryn plus MSMA applied late postemergence directed (LAYBY). Trifluralin preplant incorporated followed by fluometuron preemergence controlled common lambsquarters, eclipta, and smooth pigweed at least 90%. These herbicides also provided greater than 90% common ragweed control at two locations but only 65% control at a third location. Pyrithiobac and pyrithiobac plus MSMA EPOST increased sicklepod control more than did bromoxynil or bromoxynil plus MSMA EPOST. Bromoxynil and pyrithiobac were more effective for sicklepod control when applied in mixture with MSMA. Bromoxynil plus pyrithiobac EPOST or with MSMA controlled (≥ 90%) common lambsquarters, common ragweed, entireleaf morningglory, prickly sida, and smooth pigweed early season. But the LAYBY treatment of prometryn plus MSMA frequently improved late-season control of entireleaf morningglory, large crabgrass, prickly sida, and sicklepod. A tank mixture of MSMA plus bromoxynil or pyrithiobac and the three-component tank mixture (bromoyxnil, MSMA, plus pyrithiobac) provided a broader weed control spectrum than did either bromoxynil or pyrithiobac alone. Cotton lint yields were increased with all postemergence systems, and the LAYBY treatment of prometryn plus MSMA increased cotton yields in 13 out of 16 comparisons. High cotton yields were indicative of high levels of weed control.

Weed Control and the Use of Herbicides in Sesame Production

“…Prometryn has been widely used as a residual soil-applied and postemergence-directed herbicide in cotton grown west of the Mississippi River in the U.S. (Byrd, 2000) and controls many annual grasses and broadleaf weeds (Corbett et al, 2002;Burke & Wilcut, 2004). Prometryn is the only registered herbicide in the U.S. that provides excellent broadspectrum control of weeds such as little mallow (Malva parviflora L.), shepherdspurse (Capsella bursa-pastoris L.), common purslane (Portulaca oleracea L.), and burning nettle (Urtica urens L.) in celery (Apium graveolus L.) (Daugovish et al, 2007).…”

Soybean Response to Residual and In-Season Treatments of Trifloxysulfuron

“…Tolerant species are able to rapidly metabolize the herbicide (Askew and Wilcut 2002). Until the registration of trifloxysulfuron, pyrithiobac was the only registered selective POST herbicide for control of annual broadleaf weeds in nontransgenic cotton that does not risk reductions in yield or maturity delays (Corbett et al 2002;Dotray et al 1996;Wilcut 1998). Additionally, pyrithiobac and trifloxysulfuron are the only POST tankmixture options for annual broadleaf and perennial sedge weed control in transgenic herbicide-resistant cotton cultivars, including glufosinate-resistant, glyphosate-resistant, and bromoxynil-resistant cultivars (Corbett et al 2002;McElroy et al 2003;Richardson et al 2003;Troxler et al 2003).…”

“…Pyrithiobac controls a number of important weeds in cotton (Corbett et al 2002(Corbett et al , 2004Dotray et al 1996;Jordan et al 1993a). However, pyrithiobac does not control common lambsquarters (Chenopodium album L.), common ragweed (Ambrosia artemisiifolia L.), sicklepod [Cassia obtusifolia (L.) Irwin and Barneby], and tall morningglory [Ipomoea purpurea (L.) Roth] (Corbett et al 2004;Porterfield et al 2002a;Sunderland et al 1995).…”

Influence of Pyrithiobac Application Rate and Timing on Weed Control and Cotton Yield in Greece1

“…However, the degree of tolerance may depend on cotton variety and crop growing conditions (Harrison et al 1996;Shankle et al 1996). Efficacy of pyrithiobac against broadleaf weeds can be increased when applied in mixture with MSMA, but crop injury may also increase after that treatment (Corbett et al 2002;Monks et al 1999).…”

“…Weed and cotton response to pyrithiobac has been extensively evaluated under conditions in the United States and particularly in crops grown in fields with soil pH from 5.5 to 6.4 (Corbett et al 2002;Monks et al 1999;Porterfield et al 2002Porterfield et al , 2003. However, there has been no published data examining black nightshade and common purslane response to pyrithiobac used worldwide as well as data on weed and cotton response to pyrithiobac applied in nontransgenic cotton planting area of the eastern Mediterranean, where the soil pH of most fields grown with cotton ranges from 7.0 to 8.0 and the prevailing conditions are warm, dry, with low rainfall and low humidity.…”