Dunk Porterfield

Weed management with CGA-362622, fluometuron, and prometryn in cotton

Abstract An experiment conducted at five locations in North Carolina during 1998 and 1999 evaluated weed management systems in cotton with CGA-362622 and pyrithiobac. Weed management systems evaluated different combinations with or without fluometuron preemergence (PRE) followed by (fb) CGA-362622 early postemergence (EPOST), postemergence (POST), or EPOST + POST; or pyrithiobac EPOST fb prometryn plus MSMA late postemergence directed (LAYBY) or no LAYBY treatment. The weed species evaluated include common ragweed, entireleaf morningglory, pitted morningglory, prickly sida, sicklepod, tall morningglory, and yellow nutsedge. Fluometuron PRE improved the control of all weed species by at least 17 percentage points and increased cotton lint yield compared with the systems that did not use fluometuron PRE. Prometryn plus MSMA LAYBY improved the control of all weed species and increased lint yield compared with the systems that did not use prometryn plus MSMA LAYBY when PRE or POST herbicides were used. Control with CGA-362622 at all application timings was greater than 70% for all weed species evaluated (common ragweed, entireleaf morningglory, pitted morningglory, sicklepod, tall morningglory, and yellow nutsedge), except prickly sida. Control of all three morningglory species and prickly sida was at least 70% with pyrithiobac, whereas control of common ragweed, sicklepod, and yellow nutsedge was lower. The only cotton that yielded over 800 kg ha−1 was treated with fluometuron PRE fb CGA-362622 EPOST, POST, or EPOST + POST fb prometryn plus MSMA LAYBY. Cotton treated with pyrithiobac EPOST gave yields that were similar to those given by cotton treated with CGA-362622 EPOST in systems with fluometuron PRE and less than those given by cotton treated with CGA-362622 EPOST in systems without fluometuron PRE. Early-season injury with CGA-362622 was greater than 60% at Clayton and Rocky Mount in 1998, whereas 12% or less injury was observed at the other locations. Pyrithiobac resulted in 25 to 45% injury at these two locations. No injury was observed 45 d after treatment. Nomenclature: CGA-362622; fluometuron; MSMA; prometryn; pyrithiobac; common ragweed, Ambrosia artemisiifolia L. AMBEL; yellow nutsedge, Cyperus esculentus L. CYPES; entireleaf morningglory, Ipomoea hederacea var. integriuscula Gray IPOHG; pitted morningglory, Ipomoea lacunosa L. IPOLA; tall morningglory, Ipomoea purpurea (L.) Roth PHBPU; sicklepod, Senna obtusifolia (L.) Irwin and Barnaby CASOB; prickly sida, Sida spinosa L. SIDSP; cotton, Gossypium hirsutum L. ‘Stoneville 474’.

CGA-362622 Antagonizes Annual Grass Control with Clethodim1

Abstract: Field and greenhouse experiments were conducted to evaluate clethodim, CGA-362622, mixtures thereof, and sequential treatments for control of broadleaf signalgrass, fall panicum, goosegrass, and large crabgrass. In greenhouse experiments, clethodim alone provided 93 and 100% control of three- to four-leaf goosegrass at the low (105 g ai/ha) and high (140 g/ha) rates, respectively, whereas CGA-362622 did not control grasses in greenhouse or field experiments. Control of six- to eight-leaf goosegrass in the greenhouse with clethodim was 75% for the low rate and 89% for the high rate. Control of goosegrass in greenhouse studies was reduced at least 43 percentage points with CGA-362622 and clethodim at the high rate in mixture compared with control provided by clethodim at the high rate alone. When CGA-362622 and clethodim were applied in mixture in field studies, the effectiveness of the graminicide was decreased from > 97 to < 57% control for all annual grasses. Antagonism of clethodim activity was greater than that of the tank mixture when clethodim was applied 1 d after CGA-362622 on large crabgrass, goosegrass, and fall panicum. Clethodim applied 7 d before or after CGA-362622 controlled the four grass species as well as did clethodim applied alone. When CGA-362622 was applied to goosegrass alone, fresh weight accumulation stopped for a period of 4 d compared with untreated plants. Normal growth resumed after 4 d. Nomenclature: CGA-362622, N-[(4,6-dimethoxy-2-pyrimidinyl)carbamoyl]-3-(2,2,2-trifluoroethoxy)-pyridin-2-sulfonamide sodium salt; clethodim; broadleaf signalgrass, Brachiaria platyphylla (Griseb.) Nash #3 BRAPP; fall panicum, Panicum dichotomiflorum (L.) # PANDI; goosegrass, Eleusine indica (L.) Gaertn. # ELEIN; large crabgrass, Digitaria sanguinalis (L.) Scop. # DIGSA. Additional index words: Antagonism, growth analysis, orthogonal contrasts. Abbreviations: ALS, acetolactase synthase (EC 4.1.3.18); DAT, days after treatment; POST, postemergence.

Weed-Free Yield Response of Seven Cotton (Gossypium hirsutum) Cultivars to CGA-362622 Postemergence1

Field studies were conducted in 1998 and 1999 to evaluate the response of seven cotton cultivars to CGA-362622 applied postemergence at 7.5 and 15 g ai/ha to three- to five-leaf cotton. The cultivars evaluated included Deltapine 51, Deltapine NuCotn 33B, Paymaster 1220 RR, Paymaster 1220 BG/RR, Stoneville bromoxynil-resistant 47, Stoneville 474, and Sure-Grow 125. At 1 to 2 wk after treatment (WAT), CGA-362622 at 7.5 and 15 g/ha injured all cotton cultivars 7 to 9% and 13 to 15%, respectively. Cotton injury symptoms included chlorosis and minor stunting. At 3 to 4 WAT, injury from CGA-362622 at 7.5 and 15 g/ha was 2 to 6% and 7 to 9%, respectively. Except for Paymaster 1220 RR, Deltapine NuCotn 33B, and Stoneville 474, all cotton cultivars were injured more by the higher rate than by the lower rate of CGA-362622. Injury was not visibly apparent 6 to 8 WAT. CGA-362622 at either rate had no effect on cotton lint yield. Nomenclature: CGA-362622 (proposed common name trifloxysulfuron), N-[(4,6-dimethoxy-2-pyrimidinyl)carbamoyl]-3-(2,2,2-trifluoroethoxy)-pyridin-2-sulfonamide sodium salt; cotton, Gossypium hirsutum L. ‘Deltapine 51’, ‘Deltapine NuCotn 33B’, ‘Paymaster 1220 RR’, ‘Paymaster 1220 BG/RR’, ‘Stoneville BXN 47’, ‘Stoneville 474’, ‘Sure-Grow 125’. Additional index words: Crop injury, crop yield. Abbreviations: ALS, acetolactate synthase; BXN, bromoxynil-resistant; LAYBY, late postemergence directed; POST, postemergence; WAT, weeks after treatment.

Weed management with CGA-362622 in transgenic and nontransgenic cotton

Abstract Field studies conducted at three locations in North Carolina in 1998 and 1999 evaluated crop tolerance, weed control, and yield with CGA-362622 alone and in combination with various weed management systems in transgenic and nontransgenic cotton systems. The herbicide systems used bromoxynil, CGA-362622, glyphosate, and pyrithiobac applied alone early postemergence (EPOST) or mixtures of CGA-362622 plus bromoxynil, glyphosate, or pyrithiobac applied EPOST. Trifluralin preplant incorporated followed by (fb) fluometuron preemergence (PRE) alone or fb a late POST–directed (LAYBY) treatment of prometryn plus MSMA controlled all the weed species present less than 90%. Herbicide systems that included soil-applied and LAYBY herbicides plus glyphosate EPOST or mixtures of CGA-362622 EPOST plus bromoxynil, glyphosate, or pyrithiobac controlled broadleaf signalgrass, entireleaf morningglory, large crabgrass, Palmer amaranth, prickly sida, sicklepod, and smooth pigweed at least 90%. Only cotton treated with these herbicide systems yielded equivalent to the weed-free check for each cultivar. Bromoxynil systems did not control Palmer amaranth and sicklepod, pyrithiobac systems did not control sicklepod, and CGA-362622 systems did not control prickly sida. Nomenclature: Bromoxynil; CGA-362622, N-[(4,6-dimethoxy-2-pyrimidinyl) carbamoyl]-3-(2,2,2-trifluoroethoxy)-pyridin-2-sulfonamide sodium salt; fluometuron; glyphosate; MSMA; prometryn; pyrithiobac; trifluralin; broadleaf signalgrass, Brachiaria platyphylla (Griseb.) Nash BRAPP; entireleaf morningglory, Ipomoea hederacea var. integriuscula Gray IPOHG; large crabgrass, Digitaria sanguinalis (L.) Scop. DIGSA; Palmer amaranth, Amaranthus palmeri S. Wats. AMAPA; prickly sida, Sida spinosa L. SIDSP; sicklepod, Senna obtusifolia (L.) Irwin and Barneby CASOB; smooth pigweed, Amaranthus hybridus L. AMACH; cotton, Gossypium hirsutum L. ‘Paymaster 1220 RR’, ‘Stoneville BXN 47’, ‘Stoneville 474’.

Weed Management with S-Metolachlor and Glyphosate Mixtures in Glyphosate-Resistant Strip- and Conventional-Tillage Cotton (Gossypium hirsutum L.)'

Five studies were conducted at Clayton, Rocky Mount, and Lewiston-Woodville, NC, in 2001 and 2002, to evaluate weed management, crop tolerance, and yield in strip- and conventional-tillage glyphosate-resistant cotton. Cotton was treated with two glyphosate formulations; glyphosate-IP (isopropylamine salt) or glyphosate-TM (trimethylsulfonium salt), early postemergence (EPOST) alone or in a mixture with S-metolachlor. Early season cotton injury was minimal (3%) with either glyphosate formulation alone or in mixture with S-metolachlor. Weed control and cotton yields were similar for both glyphosate formulations. The addition of S-metolachlor to either glyphosate formulation increased control of broadleaf signalgrass, goosegrass, large crabgrass, and yellow foxtail 14 to 43 percentage points compared with control by glyphosate alone. S-metolachlor was not beneficial for late-season control of entireleaf morningglory, jimsonweed, pitted morningglory, or yellow nutsedge. The addition of S-metolachlor to either glyphosate formulation increased control of common lambsquarters, common ragweed, Palmer amaranth, smooth pigweed, and velvetleaf 6 to 46 percentage points. The addition of a late postemergence-directed (LAYBY) treatment of prometryn plus MSMA increased control to greater than 95% for all weed species regardless of EPOST treatment, and control was similar with or without S-metolachlor EPOST. Cotton lint yield was increased 220 kg/ha with the addition of S-metolachlor to either glyphosate formulation compared with yield from glyphosate alone. The addition of the LAYBY treatment increased yields 250 and 380 kg/ha for glyphosate plus S-metolachlor and glyphosate systems, respectively. S-metolachlor residual activity allowed for an extended window for more effective LAYBY application to smaller weed seedlings instead of weeds that were possibly larger and harder to control. Nomenclature: Glyphosate-IP (isopropylamine salt); glyphosate-TM (trimethylsulfonium salt); S-metolachlor; MSMA; prometryn; broadleaf signalgrass, Brachiaria platyphylla (Griseb.) Nash. #3 BRAPP; common lambsquarters, Chenopodium album L. # CHEAL; common ragweed, Ambrosia artemisiifolia L. # AMBEL; entireleaf morningglory, Ipomoea hederacea var. integriuscula Gray. # IPOHG; goosegrass, Eleusine indica (L.) Gaertn. # ELEIN; jimsonweed, Datura stramonium L. # DATST; large crabgrass, Digitaria sanguinalis (L.) Scop. # DIGSA; Palmer amaranth, Amaranthus palmeri S. Wats. # AMAPA; pitted morningglory, Ipomoea lacunosa L. # IPOLA; smooth pigweed, Amaranthus hybridus L. # AMACH; velvetleaf, Abutilon theophrasti Medicus # ABUTH; yellow foxtail, Setaria glauca (L.) Beauv. # SETLU; yellow nutsedge, Cyperus esculentus L. # CYPES; cotton, Gossypium hirsutum L. Additional index words: Economic returns, herbicide-resistant crops, tillage systems. Abbreviations: fb, followed by; PDS, postemergence-directed; PREBAN, pre-emergence-banded.

Peanut (Arachis hypogaea L.) Response to Residual and In-Season Treatments of CGA-3626221

Experiments were conducted to determine peanut tolerance to CGA-362622 applied preemergence (PRE) and postemergence (POST) and to determine the potential for CGA-362622 applied PRE and POST to cotton to injure peanut grown in rotation the following year. CGA-362622 at 3.75 and 7.5 g ai/ha applied PRE visually injured peanut 11 and 16%, respectively, at 5 wk after treatment (WAT) but did not influence peanut yield. POST treatments at 3.75 and 7.5 g/ha injured peanut 63 and 93%, respectively, at 4 WAT and reduced peanut stand by 53 and 89% at 11 WAT, respectively. Peanut pod yield was reduced 73.1 and 97.9% by CGA-362622 POST at 3.75 and 7.5 g/ha, respectively, compared with the untreated weed-free control. CGA-362622 PRE at 3.75 and 7.5 g/ha reduced peanut pod yield 7.5 and 12.6%, respectively. Cotton was injured 9% or less by CGA-362622 PRE or POST at 3.75 or 7.5 g/ha and up to 25% with CGA-362622 POST at 15 g/ha. However, CGA-362622 did not influence weed-free cotton lint yields, regardless of method or rate of application. Peanuts grown in rotation were not injured, and yields were not influenced by CGA-362622 applied PRE or POST the previous year to cotton. Nomenclature: CGA-362622, N-[4,6-dimethoxy-(2-pyrimidinyl)carbamoyl]-3-(2,2,2-trifluoroethoxy)-pyridin-2-sulfonamide sodium salt; cotton, Gossypium hirsutum L.; peanut, Arachis hypogaea L. Additional index words: Carryover, crop injury, sulfonylurea herbicide. Abbreviations: ALS, acetolactate synthase; EPOST, early postemergence; LPOST, late postemergence; MPOST, mid postemergence; POST, postemergence; PRE, preemergence; WAT, weeks after treatment.

Weed Management and Crop Response with Glyphosate, S-Metolachlor, Trifloxysulfuron, Prometryn, and Msma in Glyphosate-Resistant Cotton

Field studies were conducted in five states at six locations from 2002 through 2003 to evaluate weed control and cotton response to early POST (EPOST), POST/POST-directed spray (PDS), and late POST-directed (LAYBY) systems using glyphosate-trimethylsulfonium salt (TM), s-metolachlor, trifloxysulfuron, prometryn, and MSMA. Early POST applications were made from mid May through mid June; POST/PDS applications were made from early June through mid July; and LAYBY applications were made from early July through mid August. Early season cotton injury and discoloration was minimal (< 1%) with all treatments; mid- and late-season injury was minimal (< 2%) except for trifloxysulfuron POST (11 and 9%, respectively). Annual grasses evaluated included barnyardgrass, broadleaf signalgrass, goosegrass, and large crabgrass. Broadleaf weeds evaluated included entireleaf morningglory, pitted morningglory, sicklepod, and smooth pigweed. For the EPOST, POST/PDS, and LAYBY applications, weeds were at cotyledon to 10 leaf, 1 to 25 leaf, and 2 to 25 leaf stage, respectively. Annual broadleaf and grass control was increased with the addition of s-metolachlor to glyphosate-TM EPOST systems (85 to 98% control) compared with glyphosate-TM EPOST alone (65 to 91% control), except for sicklepod control where equivalent control was observed. Annual grass control was greater with glyphosate-TM plus trifloxysulfuron PDS than with trifloxysulfuron POST or PDS, or trifloxysulfuron plus MSMA PDS (90 to 94% vs. 75 to 83% control). With few exceptions, broadleaf weed control was equivalent for trifloxysulfuron applied POST alone or PDS alone or in combination with glyphosate-TM PDS or MSMA PDS herbicide treatments (81 to 99% control). The addition of a LAYBY herbicide treatment increased broadleaf weed control by 11 to 36 percentage points compared with systems without a LAYBY. Cotton lint yield increased 420 kg/ha with the addition of s-metolachlor to glyphosate-TM EPOST treatments compared with systems without s-metolachlor EPOST. Cotton lint yield was increased 330 to 910 kg/ha with the addition of a POST herbicide treatment compared with systems without a POST/PDS treatment. The addition of a LAYBY herbicide treatment increased cotton lint yield by 440 kg/ha compared with systems without a LAYBY. Nomenclature: Glyphosate-TM, MSMA, prometryn, s-metolachlor, trifloxysulfuron, barnyardgrass, Echinochloa crus-galli (L.) Beauv. ECHCG, broadleaf signalgrass, Brachiaria platyphylla (Griseb.) Nash. BRAPP, entireleaf morningglory, Ipomoea hederacea var. integriuscula Gray. IPOHG, goosegrass, Eleusine indica (L.) Gaertn. ELEIN, arge crabgrass, Digitaria sanguinalis (L.) Scop. DIGSA, pitted morningglory, Ipomoea lacunosa L. IPOLA, sicklepod, Cassia obtusifolia L. CASOB, smooth pigweed, Amaranthus hybridus L. AMACH, cotton, Gossypium hirsutum L. ‘DP 458 RR/BG’, ‘DP 555 RR/BG’, ‘FM 989 RR/BG’, ‘PM 2344 RR/BG’, ‘ST 4793 RR’

Bromoxynil, prometryn, pyrithiobac, and MSMA weed management systems for bromoxynil-resistant cotton (Gossypium hirsutum).

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. Nomenclature: Bromoxynil, fluometuron, MSMA, prometryn, pyrithiobac, trifluralin, common lambsquarters, Chenopodium album L. #3 CHEAL; common ragweed, Ambrosia artemisiifolia L. # AMBEL; eclipta, Eclipta prostrata L. # ECLAL; entireleaf morningglory, Ipomoea hederacea var. integriuscula Gray # IPOHG; large crabgrass, Digitaria sanguinalis (L.) Scop. # DIGSA; prickly sida, Sida spinosa L. # SIDSP; sicklepod, Senna obtusifolia (L.) Irwin and Barneby # CASOB; smooth pigweed, Amaranthus hybridus L. # AMACH; cotton, Gossypium hirsutum L. ‘Stoneville BXN 47’. Additional index words: Crop injury, herbicide-resistant cotton, Brachiaria platyphylla, BRAPP. Abbreviations: EPOST, early postemergence; fb, followed by; LAYBY, late postemergence directed; PDS, postemergence directed; PRE, preemergence; PPI, preplant incorporated.

Tobacco Response to Residual and In-Season Treatments of CGA-3626221

Experiments were conducted to determine tobacco tolerance to CGA-362622 applied pretransplant (PRE-T) and postemergence (POST) to tobacco and applied the previous year preemergence (PRE) and POST to cotton. CGA-362622 applied at 3.75 or 7.5 g ai/ha PRE-T injured ‘K326’ flue-cured tobacco 1%, whereas POST treatments resulted in 4 to 5% injury. Tobacco injury was transient with no mid- or late-season injury noted. Tobacco yields from all CGA-362622 POST treatments were not different from the nontreated weed-free check. Tobacco treated with 7.5 g/ha CGA-362622 PRE-T yielded greater than nontreated weed-free tobacco or tobacco treated with CGA-362622 POST. When grown in rotation, tobacco was not injured, and yields were not influenced by CGA-362622 applied PRE or POST to cotton the previous year. Nomenclature: CGA-362622; cotton, Gossypium hirsutum L.; tobacco, Nicotiana tabacum L. Additional index words: Carryover, crop injury, sulfonylurea herbicide. Abbreviations: ALS, acetolactate synthase; LAYBY, late POST-directed; POST, postemergence; PPI, preplant incorporated; PRE, preemergence; PRE-T, pretransplant.

Corn (Zea mays L.) Response to Trifloxysulfuron1

Experiments were conducted in weed-free environments to determine corn tolerance to trifloxysulfuron applied PRE or POST, and to determine the potential for trifloxysulfuron applied PRE or POST to cotton to injure corn grown in rotation the following year. Trifloxysulfuron at 3.75, 7.5, or 15 g ai/ha applied PRE or POST resulted in 98% stand reduction of imidazolinone-tolerant (IT) corn and 100% stand reduction in conventional corn. No injury occurred to imidazolinone-resistant (IR) corn. A corn cultivar yield response was observed, with conventional nontreated corn yielding 8,850 kg/ha and greater than nontreated IT corn at 7,900 kg/ha. Nontreated IR corn yielded the least, at 6,400 kg/ha, and these yields were equivalent to trifloxysulfuron-treated IR corn at 6,590 kg/ha. Cotton treated with trifloxysulfuron PRE at any rate was injured less than 8%. Both trifloxysulfuron at 7.5 g/ha POST and pyrithiobac at 70 g ai/ha POST injured cotton 11% early in the season. Neither trifloxysulfuron nor pyrithiobac influenced weed-free cotton lint yields. When grown in rotation, corn was not injured by trifloxysulfuron or pyrithiobac applied the previous year to cotton, and yields were not influenced. Nomenclature: Trifloxysulfuron; cotton, Gossypium hirsutum L.; corn, Zea mays L. Additional index words: Carryover, crop injury, sulfonylurea herbicide. Abbreviations: ALS, acetolactate synthase.