Benghal dayflower and sicklepod are weeds of economic importance in peanut in the southeastern United States due to their extended emergence pattern and limited effective herbicides for control. Field studies were conducted near Jay, Florida, in 2022 and 2023, to evaluate the effect of planting date and herbicide combinations on Benghal dayflower and sicklepod control in peanut crops. Peanut planted in June was exposed to a higher Benghal dayflower density than peanut planted in May. Sicklepod density was similar between May and June planting dates at 28 d after preemergence and early postemergence herbicide applications, but density was greater in peanut that was planted in June, 28 d after the mid-postemergence application. A preemeergence herbicide application followed by (fb) an early postemergence application of S-metolachlor or diclosulam + S-metolachlor controlled Benghal dayflower 84% to 93% 28 d after early postemergence in peanut that was planted in May, but control was reduced to 58% to 78% in the crop that had been planted in June. Regardless of planting date, a preemeergence application fb S-metolachlor or diclosulam + S-metolachlor applied early postemergence provided <80% sicklepod control 28 d after early postemergence. Imazapic + dimethenamid-P + 2,4-DB applied postemergence improved Benghal dayflower control to at least 94% 28 d after mid-postemergence, but sicklepod control was not >85%. Regardless of the planting date, paraquat + bentazon + S-metolachlor applied early postemergence was required to achieve ≥95% sicklepod control. However, herbicide combinations that included paraquat + bentazon + S-metolachlor reduced peanut yield when planting was delayed to June. In fields that are infested with Benghal dayflower and sicklepod, it is recommended that peanut be planted in early May to minimize the potential impact of these weeds and to increase peanut yield. Late-planted peanut required more intensive herbicide applications to obtain the same peanut yield as the May-planted peanut.

Sicklepod is one of the most difficult to control weeds in peanut production in the southeastern United States due to its extended emergence pattern and limited effective herbicides for control. Growers rely on preemergence herbicides as the foundation of their weed control programs; however, postemergence herbicides are often needed for season-long weed control. The objectives of this study were to evaluate the effect of planting pattern and herbicide combinations for sicklepod control in peanut crops. Due to rapid canopy closure, twin-row planting improved late-season sicklepod control by 13% and peanut yield by 5% compared with a single-row pattern. A preemergence application of fluridone, flumioxazin, or fluridone + flumioxazin provided 76% to 89% control of sicklepod 28 d after preemergence. Regardless of the herbicide applied preemergence, paraquat + bentazon + S-metolachlor applied early postemergence was required to achieve ≥90% sicklepod control 28 d after early postemergence. All preemergence herbicide treatments followed by (fb) S-metolachlor or diclosulam + S-metolachlor applied early postemergence provided <90% control 28 d after early postemergence. A mid-postemergence application of imazapic + dimethenamid-P + 2,4-DB controlled sicklepod by 67% to 79% prior to peanut harvest, and biomass reduction was unacceptable (<80%), resulting in difficulty in peanut digging. The highest peanut yield was observed when paraquat + bentazon + S-metolachlor was applied early postemergence fb imazapic + dimethenamid-P + 2,4-DB applied mid-postemergence. Based on the results of this study, a herbicide combination of paraquat + bentazon + S-metolachlor is an important early-season tool for controlling sicklepod in peanut crops. The results also showed that a twin-row planting pattern improved late-season sicklepod control but did not reduce herbicide input to protect peanut yield.

Pink purslane is often ranked as one of the most troublesome weeds in vegetable production systems in Georgia. Pink purslane encroachment along field edges and in-field of agronomic crops has recently increased. Postemergence herbicides are an effective component of agronomic crop weed management. However, little research has addressed pink purslane control in agronomic crops. Therefore, greenhouse and field studies were conducted from 2022 to 2023 in Tifton, Georgia, to evaluate the response of pink purslane to postemergence herbicides commonly used in agronomic crops. Greenhouse screening provided preliminary evidence whereby 13 of the 21 postemergence herbicides evaluated provided ≥80% aboveground biomass reductions. These 13 herbicides were then used for field studies. Results from the field studies, pooled across two locations, indicated that only three of the 13 herbicides provided aboveground biomass reductions of ≥70% compared to the nontreated control. Those herbicides included atrazine at 1,682 g ai ha−1, glufosinate at 656 g ai ha−1, and lactofen at 219 g ai ha−1 with 79%, 70%, and 83% biomass reduction, respectively (P < 0.05). This research suggests that many of the postemergence herbicides used on agronomic crops will not effectively control pink purslane. Thus, when trying to manage pink purslane with postemergence herbicides in agronomic crops, growers should plant crops or cultivars that are tolerant of either atrazine, glufosinate, lactofen, or a combination of these.

Cover crops can provide many benefits to peanut and cotton crops planted in rotation including suppressing weeds, conserving soil moisture after termination, increasing soil organic matter, and reducing soil erosion. However, herbicide carryover can affect cover crop establishment. The objective of this study was to investigate the responses of 6 cover crops (daikon radish, cereal rye, oat, crimson clover, winter wheat, and common vetch) to 12 soil residual herbicides. A multiyear (2016–2018), multilocation study was conducted in Macon and Henry counties, Alabama. Herbicide treatments included S-metolachlor, acetochlor, pyroxasulfone, diclosulam, imazapic, chlorimuron-ethyl, bentazon plus acifluorfen, pyrithiobac-sodium, trifloxysulfuron-sodium, diuron, prometryn, and flumioxazin, each applied at 10% of the full-labeled rate. At 42 to 52 and 145 to 149 d after planting (DAP), cover crop plant heights and stand counts were evaluated, as was biomass at 145 to 149 DAP. Treatments varied from year to year but not locations. In 2016, significant stand reductions (P ≤ 0.10) of 36% to 43% in rye and 44% to 75% in wheat were observed at 48 to 52 DAP for S-metolachlor, acetochlor, pyroxasulfone, imazapic, and bentazon plus acifluorfen compared with nontreated plants. Vetch had stand reductions ranging from 14% to 80% for all treatments 50 DAP except for plants treated with prometryn. S-metolachlor, pyroxasulfone, and acetochlor reduced stands of rye, wheat, and vetch more than any other herbicides. In 2017, at 147 to 149 DAP, clover stands were reduced by 29% with diclosulam and by 38% with trifloxysulfuron-sodium. Similarly, radish stands were reduced by 64% with diclosulam treatment. No significant biomass reductions were observed for any cover crop species either year. Oat showed the most tolerance with no treatments reducing any growth parameters either year. Although initial injury and stunting may occur, biomass at termination of cover crops were not affected by herbicide residues evaluated in this study.

Field studies were conducted at five locations in North Carolina and Virginia in 1996 and 1997 to evaluate weed control and peanut (Arachis hypogaea) response to diclosulam that was applied preemergence (PRE) and in systems with commercial standards. All plots received a preplant incorporated (PPI) treatment of ethalfluralin at 840 g ai/ha. Diclosulam controlled common lambsquarters (Chenopodium album L.), eclipta (Eclipta prostrata L.), entireleaf morningglory (Ipomoea hederacea var. integriuscula Gray), ivyleaf morningglory [Ipomoea hederacea (L.) Jacq.], pitted morningglory (Ipomoea lacunosa L.), and prickly sida (Sida spinosa L.) as well as and frequently better than the commercial standards of acifluorfen plus bentazon applied postemergence (POST), paraquat plus bentazon early POST followed by (fb) imazapic POST, or imazapic POST. Systems with ethalfluralin PPI plus diclosulam PRE at 26 g ai/ha fb acifluorfen plus bentazon POST controlled a broader spectrum of weeds and yielded greater than systems of ethalfluralin PPI fb imazapic POST or ethalfluralin PPI fb acifluorfen plus bentazon POST. Peanut exhibited excellent tolerance to diclosulam PRE at 17, 26, or 35 g/ha.

Due to the limited availability of selective herbicides to control Sumatran fleabane after soybean emergence, it is essential to develop new options that provide effective control prior to planting. A new herbicide formulation containing diclosulam+halauxifen-methyl was evaluated for effectiveness at two Sumatran fleabane plant heights (5 to 10 cm, and 10 to 50 cm) and for soybean selectivity when applied at 7 or 3 d before planting. Combined results from the two sites showed that diclosulam+halauxifen, applied either alone or in a tank mixture with glyphosate, and the tank mixture of diclosulam+2,4-D amine+glyphosate are effective at all rates tested to control Sumatran fleabane in preplant applications. Crop response was observed with applications 7 days before planting at only one of the sites. A rate-dependent crop response was observed for pre-plant applications performed 3 days before soybean planting. However, crop yield was not significantly affected for either timing across all rates. All rates tested of diclosulam+halauxifen in this study were considered safe to soybean.

Field experiments were conducted in 1996 and 1997 to evaluate the tolerance of imidazolinone-resistant (IR) and non-IR corn cultivars to preemergence (PRE) and postemergence (POST) treatments of diclosulam. Crop injury was evaluated early- (5 to 6 wk after planting [WAP]), mid- (10 to 11 WAP), and late-season (13 to 15 WAP). Early-season injury of IR corn was no more than 12% in systems that included diclosulam PRE or POST at 18, 27, or 36 g ai/ha. Early-season injury of non-IR corn ranged from 85 to 89% in systems that included diclosulam PRE at any rate. At the mid-season evaluation, crop injury to IR corn was 1% or less. Non-IR corn was injured 73 to 94% in systems that included diclosulam PRE, while systems that included diclosulam POST caused 45 to 58% injury at mid-season. At the late-season evaluation, non-IR corn was injured 56, 88, and 96% with diclosulam PRE at 18, 27, and 36 g/ha, respectively, whereas systems that included diclosulam POST had 11 to 14% injury. Injury to IR corn from diclosulam PRE or POST was not apparent at the late-season evaluation. Weed-free yield of IR corn treated with diclosulam was 6,490 to 6,850 kg/ha and was equivalent to or better than yield from IR corn treated only with atrazine plus metolachlor PRE. Yield from non-IR corn treated with any diclosulam-containing system did not exceed 3,770 kg/ha.

Field studies were conducted near Sparr, FL, in 2001 and 2002 to evaluate the response of ‘Valencia 102’ grown for the green peanut market (or boiling peanut) to preemergence (PRE) and postemergence (POST) applications of herbicides registered for dry peanut production (roasted market). Green peanut exhibited excellent tolerance to most PRE and POST treatments. There was minimal injury (8%) from flumioxazin applications when evaluated early season in both years, and peanut quickly recovered. Norflurazon caused chlorosis to peanut foliage (23%) in both years. Yield reduction was observed in 2001 for flumioxazin (15%), metolachlor (20%), and norflurazon (41%) compared with the untreated control. However, there were no yield reductions for any of the PRE treatments in 2002. Bentazon + paraquat early postemergence (EPOST) followed by (fb) 2,4-DB POST, bentazon + paraquat EPOST fb clethodim POST, and imazapic EPOST caused ≤5% injury and had no effect on yield in either year.

Field studies were conducted in 2000 and 2001 in Plains, GA, to determine peanut and weed response to the residual herbicides sulfentrazone, imazapic, diclosulam, and flumioxazin. Herbicide treatments included sulfentrazone applied preemergence (PRE) or preplant incorporated (PPI) at 112, 168, 224, and 280 g ai/ha, imazapic postemergence (POST) at 71 g ai/ha, diclosulam PPI at 26 g ai/ha, and flumioxazin PRE at 88 g ai/ha. Peanut exhibited early-season injury from all herbicide treatments, ranging from 0 to 10% for sulfentrazone PPI or PRE, 10% for imazapic, 3 to 23% for flumioxazin, and 1 to 7% for diclosulam. Yields were similar for sulfentrazone PPI- or PRE-treated and flumioxazin-, imazapic-, and diclosulam-treated peanut. Yellow nutsedge control was 83% or greater with all rates of sulfentrazone PRE or PPI, 83 and 90% with diclosulam, and 96 and 99% with imazapic, respectively. Flumioxazin did not control yellow nutsedge or wild poinsettia. Tall morningglory control was 82% or greater with imazapic, diclosulam, flumioxazin, and sulfentrazone PPI or PRE at 168 g/ha or higher. Florida beggarweed control was 88% or greater with diclosulam, flumioxazin, and sulfentrazone PRE at 224 and 280 g/ha. Overall, peanut tolerance to sulfentrazone at 112 to 280 g/ha PPI and PRE was high and yield was equivalent to the currently registered peanut residual herbicides.

Experiments were conducted at the Upper Coastal Plain Research Station near Rocky Mount and at the Peanut Belt Research Station near Lewiston-Woodville in 2002 and 2003. Peanut injury was minimal (< 5%) with all soil-applied programs. S-Metolachlor PRE alone or in mixture with sulfentrazone, diclosulam, or flumioxazin controlled annual grasses similarly (66 to 87%). The addition of imazapic plus 2,4-DB POST increased annual grass control (> 93%). Sulfentrazone or diclosulam in mixture with S-metolachlor were the best PRE options, with 94% and 92% control of yellow and purple nutsedge, respectively, with flumioxazin being least effective at 70%. Diclosulam and flumioxazin in mixture with S-metolachlor were the best PRE options, with 99% and 93%, respectively for common ragweed control, whereas sulfentrazone was the least effective at 65%. S-Metolachlor in mixture with sulfentrazone, diclosulam, or flumioxazin PRE were similar (87 to 90%) for common lambsquarters control. S-Metolachlor in mixture with sulfentrazone, diclosulam, or flumioxazin provided similar levels of entireleaf, ivyleaf, pitted, and tall morningglory control (87, 86, and 87%, respectively) and better than S-metolachlor alone at 64%. Flumioxazin in mixture with S-metolachlor was the best PRE option for control of Palmer amaranth at 96%, whereas diclosulam with S-metolachlor was the best PRE option for control of eclipta at 100%. The prepackaged mixture of acifluorfen and bentazon plus 2,4-DB POST and imazapic plus 2,4-DB POST were similar for all morningglory species (> 96%) and Palmer amaranth control (93 and 97%, respectively). Peanut treated with S-metolachlor plus diclosulam PRE numerically yielded the highest at 3,210 kg/ha, but were statistically equivalent to S-metolachlor plus flumioxazin PRE at 3,040 kg/ha. Peanut treated with imazapic plus 2,4-DB POST yielded the most at 3,400 kg/ha, while peanut treated with a prepackaged mixture of acifluorfen and bentazon plus 2,4-DB POST yielded less (3,070 kg/ha).

Field studies were conducted at Lewiston–Woodville and Rocky Mount, NC in 2001 and 2002 to evaluate weed control and peanut response to POST treatments of diclosulam at various rates and application timings. Diclosulam controlled common ragweed and entireleaf morningglory when applied within 35 d after planting (DAP). Common ragweed 61 cm tall was controlled ≥92% with 4 to 13 g ai/ha diclosulam and larger common ragweed (107 to 137 cm tall) were controlled ≥97% with 27 g/ha diclosulam. Common lambsquarters was controlled 62% or less with all diclosulam POST treatments following metolachlor applied PRE, which provided 48% control. Peanut injury was less than 15% with all diclosulam POST treatments and was transitory. In separate studies, POST diclosulam treatments did not affect peanut yield in a weed-free environment. Peanut yield in weedy environments was reduced as the diclosulam application timing was delayed because of early season weed interference. A linear relationship was observed between yield and application timing with yield decreasing as application timing was delayed. This yield response documents the importance of early season weed management for maximizing peanut yield potential. Virginia peanut varieties were not affected by different POST rates of diclosulam; however, early season peanut injury showed a linear and quadratic relationship with diclosulam rate and was less than 14% at rates as high as 71 g/ha, and was not apparent by late season.

Diclosulam is registered for residual and postemergence control of several broadleaf weeds and suppression of annual sedges in peanut in the southeastern United States. Many producers apply herbicides and other pesticides simultaneously to increase the spectrum of pest control or to increase efficiency of operations. However, compatibility of coapplication of pesticides is a concern. Field trials were conducted to evaluate the compatibility of diclosulam with other herbicides and fungicides. Horseweed control by diclosulam in combination with glyphosate, sulfosate, or paraquat was compared to combinations of these herbicides with flumioxazin, tribenuron plus thifensulfuron, or 2,4-D. All treatments that contained diclosulam controlled horseweed at least 86%. Broadleaf signalgrass control by clethodim and sethoxydim was not affected by diclosulam; however, large crabgrass control was reduced when graminicides were coapplied with diclosulam. Common ragweed control was reduced when diclosulam was applied with chlorothalonil and pyraclostrobin but not by azoxystrobin or tebuconazole.

Napiergrass has potential as a cellulosic biofuel crop because of its rapid growth habit in the southern United States. However, it is also listed as a potential invasive species by the Florida Exotic Pest Plant Council. For field renovation, information about napiergrass control in response to tillage and herbicides is required. Field studies were initiated to evaluate control of napiergrass established in fields for over 3 yr at Plains, GA, and Tifton, GA. For tillage and POST herbicides, imazapyr plus glyphosate consistently controlled napiergrass relative to diclosulam plus glyphosate, sulfentrazone plus glyphosate, or tillage in terms of visual injury, stem height and dry biomass reduction. One application of imazapyr plus glyphosate controlled napiergrass 74 and 94%, and reduced plant stem height to 6 and 15% of the nontreated control. When diclosulam plus glyphosate, sulfentrazone plus glyphosate, or tillage was used alone with no sequential herbicides, napiergrass control ranged from 12 to 33%; when these control tactics were followed by two sequential applications of either sethoxydim or glyphosate, napiergrass control varied from 45 to 99%. Reductions in plant heights were reflective of injury 47 d after final herbicide applications (May/June). Napiergrass yield in dry biomass production was reduced by imazapyr plus glyphosate ≥ 86% relative to the nontreated control (NTC). Diclosulam plus glyphosate, sulfentrazone plus glyphosate, or tillage alone was not effective in reducing napiergrass dry biomass yields ranging from 1 to 47% compared with the NTC; when these treatments were followed by sequential applications of sethoxydim or glyphosate, napiergrass dry biomass was reduced 46 to 91% compared with the NTC. Tillage plus two applications of sethoxydim or glyphosate exhibited control potential because they provided levels of napiergrass control similar to imazapyr-based treatments. Tillage plus multiple applications of sethoxydim or glyphosate offers flexibility to crop rotations as compared with the residual herbicide imazapyr, which has many crop rotation restrictions because of carryover concerns.

Research was conducted in North Carolina to compare weed control by various rates of imazapic POST alone or following diclosulam PRE. In a second experiment, weed control by imazapic applied POST alone or with acifluoren, diclosulam, or 2,4-DB was compared. In a final experiment, yellow nutsedge control by imazapic alone and with the fungicides azoxystrobin, chlorothalonil, pyraclostrobin, and tebuconazole was compared. Large crabgrass was controlled more effectively by imazapic POST than diclosulam PRE. Common lambsquarters, common ragweed, and eclipta were controlled more effectively by diclosulam PRE than imazapic POST. Nodding spurge was controlled similarly by both herbicides. Few differences in control were noted when comparing imazapic rates after diclosulam PRE. Applying either diclosulam PRE or imazapic POST alone or in combination increased peanut yield over nontreated peanut in five of six experiments. Few differences in pod yield were noted when comparing imazapic rates. Acifluorfen, diclosulam, and 2,4-DB did not affect entireleaf morningglory, large crabgrass, nodding spurge, pitted morningglory, and yellow nutsedge control by imazapic. Eclipta control by coapplication of imazapic and diclosulam exceeded control by imazapic alone. The fungicides azoxystrobin, chlorothalonil, pyraclostrobin, and tebuconazole did not affect yellow nutsedge control by imazapic.

A perennial species in its native range of Asia and Africa, Benghal dayflower in North America establishes annually from seed. This species has the unique ability to produce aerial and subterranean flowers and seeds. Information on how various environmental factors affect Benghal dayflower aerial and subterranean seed germination and emergence in the United States is lacking. Studies were conducted to determine the effect of temperature, planting depth, salt concentration, and pre-emergence herbicides on germination or emergence of aerial and subterranean Benghal dayflower seed. Maximum aerial seed germination occurred at 30 C, whereas maximum subterranean seed germination occurred at 30 and 35 C. Germination at 40 C was delayed relative to optimum temperatures. The seed coats in this study were mechanically disrupted to evaluate the response of seeds to temperature in the absence of physical dormancy. The physical dormancy imposed by the seed coat could require additional study. Benghal dayflower was not tolerant to ≥ 10 mM NaCl, indicating that this exotic species is not likely to become problematic in brackish marshes and wetlands of coastal plain regions. There was an inverse linear response of Benghal dayflower emergence and planting depth, with no emergence occurring at a planting depth of 12 cm. A field survey of Benghal dayflower emergence revealed that 42% of plants established from a depth of 1 cm in the soil profile, with 7 cm being the maximum depth from which seedlings plants could emerge. This suggests that PRE herbicides must remain in the relatively shallow depths of the soil profile to maximize control of germinating seedlings. Subterranean seeds were less sensitive than aerial seeds to S-metolachlor, the primary means of controlling this species in cotton. There were no differences between the germination of aerial and subterranean seed in response to treatment with diclosulam.

Palmer amaranth resistance to acetolactate synthase (ALS)–inhibiting herbicides was first identified in Georgia in 2000. Since then, complaints from peanut producers have increased concerning failure of ALS herbicides in controlling Palmer amaranth. Because efficacy of ALS herbicides can be compromised under adverse conditions, seeds from Palmer amaranth plants that escaped weed control were collected across the peanut-growing region in Georgia to investigate the cause of these reported failures. Greenhouse and growth-chamber studies were conducted using these seeds to evaluate whether weed escapes were a result of Palmer amaranth resistance to ALS herbicides. Each of the 61 accessions collected across Georgia exhibited varying levels of resistance to imazapic applied POST (< 55% control, relative to ALS-susceptible Palmer amaranth). Subsamples of the accessions were evaluated for their response to imazapic rates, which indicated variable levels of resistance across Palmer amaranth accessions. The rate of imazapic that provided 50% reduction in Palmer amaranth plant biomass (I50) for the known susceptible biotype was 0.9 g/ha of imazapic. Of the 10 accessions evaluated, 8 of them had I50 values that ranged from 3 to 297 g/ha of imazapic. The other two accessions could not be fit to the log-logistic dose–response curve and had undeterminable I50 values because of high levels of ALS resistance (> 1,400 g/ha of imazapic). Herbicide cross-resistance experiments indicated that 30 accessions were resistant to the ALS herbicides imazapic, chlorimuron, pyrithiobac, and diclosulam at the recommended field-use rates. However, each of these 30 accessions was susceptible to glyphosate. These data demonstrate that ALS-resistant Palmer amaranth occurs throughout the peanut-growing region of Georgia. Growers in Georgia will need to alter their weed-control programs in peanut to include herbicides with multiple modes of action that do not rely on ALS herbicides for effective Palmer amaranth control.

Field studies were conducted at two locations in North Carolina in 1998 and in 1999 to evaluate weed control and peanut response following diclosulam at 27 g ai/ha preemergence (PRE) or flumioxazin at 87 g ai/ha preemergence (PRE) alone and in systems with postemergence (POST) commercial standards. All plots received a preplant incorporated (PPI) treatment of metolachlor at 1,400 g ai/ha. Metolachlor PPI plus diclosulam or flumioxazin PRE controlled common lambsquarters, common ragweed, entireleaf morningglory, large crabgrass, and yellow nutsedge as well as or better than metolachlor PPI followed by (fb) acifluorfen plus bentazon POST or paraquat plus bentazon early postemergence fb acifluorfen plus bentazon POST. Metolachlor PPI plus diclosulam PRE or flumioxazin PRE controlled ivyleaf morningglory as well as metolachlor PPI fb acifluorfen plus bentazon POST. Metolachlor PPI plus flumioxazin PRE controlled common lambsquarters better than metolachlor PPI plus diclosulam PRE while diclosulam PRE controlled common ragweed better. There was no difference in common lambsquarters control between flumioxazin and diclosulam PRE when POST herbicides were used. There was only one difference in peanut yield and net returns between metolachlor PPI fb either diclosulam or flumioxazin PRE when POST herbicides were used.

Palmer amaranth has greatly disrupted agricultural practices in the United States with its rapid growth and rapid evolution of herbicide resistance. This weed species is now suspected in Argentina. To document whether the suspected plant populations are indeed Palmer amaranth, molecular comparisons to known standards were conducted. Additionally, these same plant populations were screened for possible herbicide resistance to several acetolactate synthase (ALS)-inhibiting herbicides. Sequencing data confirmed that suspected populations (A2, A3, A4) were indeed Palmer amaranth. Another population (A1) was tested to determine whether hybridization had occurred between Palmer amaranth and mucronate amaranth the native amaranth species of the region. Tests confirmed that no hybridization had occurred and that A1 was simply a unique phenotype of mucronate amaranth. Each population was screened for resistance to imazapic, nicosulfuron, and diclosulam. All Palmer amaranth populations from Argentina were shown to be resistant to at least one ALS-inhibiting herbicide. The populations were then subjected to further testing to identify the mutation responsible for the observed ALS resistance. All mucronate amaranth populations exhibited a mutation previously documented to confer ALS resistance (S653N). No known resistance-conferring mutations were found in Palmer amaranth.

Experiments were conducted in Lewiston, NC, in 1999 and 2000 and Rocky Mount, NC, in 1999 to evaluate weed management systems in strip- and conventional-tillage peanut. The peanut cultivars grown were ‘NC 10C’, ‘NC 12C’, and ‘NC 7’, respectively. Weed management systems consisted of different combinations of preemergence (PRE) herbicides including diclosulam and flumioxazin plus commercial postemergence (POST) herbicide systems. Dimethenamid plus diclosulam or flumioxazin PRE controlled common lambsquarters, eclipta, and prickly sida at least 91%. Diclosulam and flumioxazin provided variable control of three Ipomoea species (59 to 91%) and bentazon plus acifluorfen POST provided > 90% control. Only diclosulam systems controlled yellow nutsedge 90% late season. Annual grass control required clethodim late POST, regardless of tillage system. Dimethenamid plus diclosulam or flumioxazin PRE produced equivalent yields and net returns with no significant differences between the two PRE options. Both systems produced higher yields and net returns than dimethenamid regardless of the POST herbicide option. The tillage production system did not influence weed control of eight weeds, peanut yields, or net returns. The addition of diclosulam or flumioxazin to dimethenamid PRE improved weed control compared with dimethenamid PRE alone.

Field trials were conducted in 2003/2004 and 2005/2006 at Reidsville, Georgia, to evaluate the effects of previously applied residual herbicides on onion growth and bulb production. Before transplanting onion, preplant applications of imazapic at 18 and 36 g ai/ha, diclosulam at 7 and 14 g ai/ha, pyrithiobac at 27 and 54 g ai/ha, trifloxysulfuron at 6.6 and 13.2 g ai/ha, diuron at 224 and 448 g ai/ha, and cloransulam at 22 g ai/ha were made. An untreated control was included for comparison. Trifloxysulfuron at 13.2 g/ha, diclosulam at 14 g/ha, pyrithiobac at 54 g/ha, and cloransulam at 22 g/ha injured onion 26, 73, 86, and 86% in 2003/2004, respectively, and 13 to 44% injury in 2005/2006. These same herbicides also reduced yield. Imazapic and diuron injured transplanted onion 6% during both seasons but did not reduce yield. This research suggests imazapic and diuron restrictions could possibly be reduced. However, the onion rotational restrictions for diclosulam, pyrithiobac, trifloxysulfuron, and cloransulam are accurate.