Late Postemergence Research Articles

Integrating fall‐planted cereal rye cover crop with herbicides for reducing Palmer amaranth seed production in soybean under planting green conditions

AbstractCover crops are usually terminated prior to planting the cash crop; however, “planting green” is an alternative approach that allows growers to plant cash crop into an actively growing, green cover crop, which is then terminated after the establishment of the cash crop. The objectives of this study were (1) to determine whether planting soybean (Glycine max L. Merr.) into a standing cereal rye (Secale cereale L.) cover crop provides superior weed suppression compared to terminating cereal rye 2 weeks before soybean planting and (2) to evaluate an integrated effect of herbicide programs and cereal rye termination timing on Palmer amaranth (Amaranthus palmeri S. Watson) control, biomass, seed production, soybean grain yield, and benefit/cost ratio. Field experiments were conducted in southcentral Nebraska from 2020 to 2022. Preemergence (PRE) herbicide with 2 weeks after planting (WAP) termination of cereal rye provided >95% Palmer amaranth control in 2021 and varied from 88% to 98% in 2022 at 28 days after PRE. A PRE herbicide followed by (fb) late‐postemergence (LPOST) herbicide with 2 WAP termination of cereal rye controlled Palmer amaranth 85%–92% in 2021 compared with 97%–99% control 28 days after LPOST herbicide application in 2022. Palmer amaranth density was higher with 2 WBP cereal rye termination compared with 2 WAP termination regardless of the herbicide program. PRE fb LPOST herbicide programs integrated with 2 WAP termination of cereal rye reduced Palmer amaranth seed production to less than 9100 seeds plant−1 in 2021 and no seed production in 2022. In 2021, terminating cereal rye 2 WAP played an integral role in controlling and reducing the density of Palmer amaranth; however, it had noticeable impact on soybean yield compared to terminating 2 WBP. In 2022, hail and windstorm had a confounding effect on soybean stand and yield.

Two-Pass Weed Management Programs for Identity-Preserved Soybean

Weed management is a challenge in Identity-Preserved (IP) soybean in Ontario, Canada. Six experiments were established in southwestern Ontario, Canada during 2021 and 2022 to evaluate weed control and soybean yield with preemergence (PRE), early postemergence (EPOST), and PRE followed by (fb) late POST (LPOST) herbicide programs. At 8 weeks after LPOST herbicide applications, S-metolachlor/metribuzin, pyroxasulfone/sulfentrazone, and flumioxazin/metribuzin/imazethapyr applied PRE provided 7, 49, and 99% control of velvetleaf; 65, 98, and 100% control of green pigweed; 7, 8, and 82% control of common ragweed; 25, 68, and 98% control of common lambsquarters; 91, 77, and 89% control of barnyardgrass; and 62, 68, and 93% control of green foxtail, respectively. Imazethapyr + bentazon applied EPOST provided 91% control of velvetleaf; 91% control of green pigweed; 78% control of common ragweed; 95% control of common lambsquarters; 76% control of barnyardgrass; and 79% control of green foxtail. S-metolachlor/metribuzin, pyroxasulfone/sulfentrazone, and flumioxazin/metribuzin/imazethapyr applied PRE fb bentazon + fomesafen + quizalofop applied LPOST provided 61, 86, and 100% control of velvetleaf; 97, 99, and 100% control of green pigweed; 94, 88, and 99% control of common ragweed; 96, 98, and 100% control of common lambsquarters; 97, 95, and 97% control of barnyardgrass; and 97, 96, and 99% control of green foxtail, respectively. There was minimal and transient soybean injury (6% or less) with all PRE or EPOST herbicide treatments, however, S-metolachlor/metribuzin, pyroxasulfone/sulfentrazone, or flumioxazin/metribuzin/imazethapyr applied PRE fb bentazon + fomesafen + quizalofop LPOST caused up to 22% injury in soybean. Weed interference reduced soybean yield 40%. Weed interference with S-metolachlor/metribuzin and pyroxasulfone/sulfentrazone applied PRE reduced soybean yield 25 and 31%, respectively. Reduced weed interference with flumioxazin/metribuzin/imazethapyr applied PRE, imazethapyr + bentazon applied EPOST, and the two-pass programs of a PRE fb LPOST herbicide resulted in soybean yield that was similar to the weed-free control. This study concludes that there are many effective weed management programs in IP soybean; however, the two-pass weed control programs are recommended since they provide good to excellent weed control, minimize soybean yield loss from weed interference, and ensure the use of multiple herbicide modes of action which reduces the selection intensity for the evolution of herbicide-resistant weeds.

Effect of herbicide programs on control and seed production of multiple herbicide–resistant Palmer amaranth (Amaranthus palmeri) in corn resistant to 2,4-D/glufosinate/glyphosate

Abstract Multiple herbicide–resistant (MHR) Palmer amaranth is among the most problematic summer annual broadleaf weeds in Nebraska and several other states. A new MHR corn cultivar (resistant to 2,4-D/glufosinate/glyphosate, also known as Enlist corn) has been commercially available in the United States since 2018. Growers are searching for herbicide programs for control and reduce seed production of MHR Palmer amaranth among Enlist corn crops. The objectives of this study were to evaluate herbicides applied preemergence, early postemergence, or preemergence followed by (fb) late postemergence for the management of MHR Palmer amaranth in Enlist corn fields and to assess their effect on Palmer amaranth biomass, density, seed production, and corn yield. Field experiments were conducted near Carleton, NE, in 2020 and 2021, in a grower’s field of Enlist corn infested with acetolactate synthase–inhibitor/atrazine/glyphosate–resistant Palmer amaranth. Herbicides applied preemergence, such as flufenacet/isoxaflutole/thiencarbazone-methyl, acetochlor/clopyralid/flumetsulam, or acetochlor/clopyralid/mesotrione, provided 75% to 99% control of Palmer amaranth 30 d after preemergence. Preemergence fb late postemergence herbicides resulted in 94% Palmer amaranth control 90 d after late postemergence, reduced weed density to 0 to 8 plants m−2 30 d after late postemergence, and reduced biomass to 2 to 14 g m−2 15 d after late postemergence compared to preemergence-only (59% control, 0 to 15 plants m−2, and 4 to 123 g m−2) and early postemergence–only herbicides (78% control, 6 to 30 plants m−2, and 8 to 25 g m−2). Based on contrast analysis, Palmer amaranth seed production was reduced to 14,050 seeds m–2 in preemergence fb late postemergence herbicide programs compared with 325,490 seed m–2 in preemergence-only and 376,750 seed m–2 in early postemergence–only programs. Based on orthogonal contrast, higher corn yield of 12,340 and 11,730 kg ha−1 was obtained with preemergence fb late postemergence herbicide programs compared with preemergence-only (10,840 and 11,510 kg ha−1) and early postemergence–only programs (10,850 and 10,030 kg ha−1) in 2020 and 2021, respectively.

Growth and fecundity of Palmer amaranth escaping glufosinate in cotton with and without grass competition

Abstract Field experiments were conducted at Clayton and Rocky Mount, NC, during summer 2020 to determine the growth and fecundity of Palmer amaranth plants that survived glufosinate with and without grass competition in cotton. Glufosinate (590 g ai ha−1) was applied to Palmer amaranth early postemergence (5 cm tall), mid-postemergence (7 to 10 cm tall), and late postemergence (>10 cm tall) and at orthogonal combinations of those timings. Nontreated Palmer amaranth was grown in weedy, weed-free in-crop (WFIC) and weed-free fallow (WFNC) conditions for comparisons. Palmer amaranth control decreased as larger plants were treated; no plants survived the sequential glufosinate applications in both experiments. The apical and circumferential growth of Palmer amaranth surviving glufosinate treatments was reduced by more than 44% compared to the WFIC and WFNC Palmer amaranth in both experiments. The biomass of Palmer amaranth plants surviving glufosinate was reduced by more than 62% when compared with the WFIC and WFNC in all experiments. The fecundity of Palmer amaranth surviving glufosinate treatments was reduced by more than 73% compared to WFNC Palmer amaranth in all experiments. Remarkably, the plants that survived glufosinate were fecund as WFIC plants only in the Grass Competition experiment. The results prove that despite decreased vegetative growth of Palmer amaranth surviving glufosinate treatment, plants remain fecund and can be fecund as nontreated plants in cotton. These results suggest that a glufosinate-treated grass weed may not have a significant interspecific competition effect on Palmer amaranth that survives glufosinate. Glufosinate should be applied to 5 to 7 cm Palmer amaranth to cease vegetative and reproductive capacities.

Growth and fecundity of Palmer amaranth escaping glufosinate in soybean with and without grass competition

Abstract Field experiments were conducted at Clayton and Rocky Mount, North Carolina, during the summer of 2020 to determine the growth and fecundity of Palmer amaranth plants that survived glufosinate with and without grass competition in soybean crops. Glufosinate (590 g ai ha−1) was applied at early postemergence (when Palmer amaranth plants were 5 cm tall), mid-postemergence (7–10 cm), and late postemergence (>10 cm) and at orthogonal combinations of those timings. Nontreated Palmer amaranth was grown in weedy (i.e., intraspecific and grass competition), weed-free in-crop (WFIC), and weed-free fallow (WFNC) conditions for comparisons. No Palmer amaranth plants survived the sequential glufosinate applications and control decreased as the plants were treated at a larger size in both experiments. The apical and circumferential growth rate of Palmer amaranth surviving glufosinate was reduced by more than 44% compared with the WFNC Palmer amaranth. The biomass of Palmer amaranth plants that survived glufosinate was reduced by more than 87% compared with the WFNC Palmer amaranth. The fecundity of Palmer amaranth that survived glufosinate was reduced by more than 70% compared with WFNC Palmer amaranth. Palmer amaranth plants that survived glufosinate were as fecund as the WFIC Palmer amaranth in both experiments in soybean fields. The results prove that despite the significant vegetative growth rate decrease of Palmer amaranth that survived glufosinate, plants can be as fecund as nontreated plants. The trends in growth and fecundity of Palmer amaranth that survives glufosinate with and without grass competition were similar. These results suggest that glufosinate-treated grass weeds may not reduce the growth or fecundity of Palmer amaranth that survives glufosinate.

Effect of Biofertilizer and Metribuzin on the Yield Traits of Potato under the Influence of Water Stress

A field experiment was conducted in Al-Mashroo area / Al-Hamzawi, affiliated to Al-Musayyib district, 35 km north of Babylon, to determine how bio-fertilizer and herbicide spraying affected potato yield and quality under different irrigation periods. The RCBD (Randomized Complete Block Design) split-split plot design was used to conduct the experiment with three replications. The experiment had three factors: irrigation periods (5, 7, and 9) days for the main plots. The second element, biofertilizer, has three levels (control treatment without CO, rhizobia R, mycorrhizal M) and sub-plots. The third component, metribuzin, has four stages (no CO, preemergence, postemergence, late postemergence) and sub-sub plots. The statistical investigation indicated that it excelled the following traits: number of marketable tubers plant-1, weight of marketable tubers (g), total yield of one plant (g. plant-1), marketing yield (ton.ha-1). The number of tubers, marketing yield, and plant yield substantially impacted pre-emergence and post-emergence treatments. The (Myco) fertilizer treatment performed better in tuber quantity, weight, and marketing yield (3.26 and 3.77 tuber plant-1, 106.5 and 107.67 g, 23.17 and 24.78 tons ha-1) for both seasons. Irrigation every 7 days increased tuber quantity, weight, yield per plant, and marketing yield (3.37 and 3.89 tubers). 384.3 and 462.3 gm, Plant-1, 112.2 and 115.53 g Plant-1 (20.85 and 22.08 tons ha-1) both seasons. The bilateral interaction between irrigation periods and herbicide was significant in tuber number and marketing yield (3.66 and 3.94 tubers.plant-1, 4.28 and 4.52 tubers.plant-1, 25.57 and 22.83 tons ha-1 and 27.11 and 24.34 tons ha-1) for both seasons. The interaction between irrigation times and biofertilizer was more significant than the 7-day interaction. For both seasons, Mycox produced 4.01 and 4.64 tubers plant-1, 113.6 and 119.70 gram, 25.52 and 27.18 tons ha-1, and marketing yield. The herbicide-bio-fertilizer interaction significantly impacted tuber production, with post-Myco interaction leading to 3.89 and 4.41 tubers per plant-1 in both seasons. The triple interaction was substantial, with 7 days post-Myco resulting in a higher number of tubers (5.32 tubers plant-1) in both seasons.

POTENTIAL SELECTIVITY OF HERBICIDES IN PRE- AND POST-EMERGENT LINSEED (LINUM USITATISSIMUM L.)

Linseed is an oilseed crop that is widely used in human and animal feed, as a cover crop in agroecosystems, and for fiber production. To facilitate the management of weeds in the crop, this study aimed to evaluate potential selective herbicides for linseed cultivation applied in pre-planting and incorporation (PPI), pre-emergence (PRE), and early (POST) and late (late POST) post-emergence stages, since there are presently no herbicides registered for use on linseed in Brazil. Therefore, four experiments were conducted in a completely randomized design with four replications, and five (exp. 1), 21 (exp. 2), 26 (exp. 3), and four (exp. 4) treatments. Crop injury and the fresh and dry matter of the plants were evaluated. Experiment 4 was conducted until seed production, and data on the final height, number of capsules, and yield were obtained. The results were characterized by the low selectivity of herbicides during pre-emergence, whether incorporated or not, and indicated 11 herbicides with potential selectivity in post-emergence, whether early or late, namely: bentazon, bentazon + imazamox, clethodim + fenoxaprop, clethodim, flumiclorac, fluazifop, flumioxazin, haloxyfop, nicosulfuron, tembotrione, and tepraloxydim. Linseed is demonstrated to be susceptible to or has low tolerance to various herbicides.

Katagon at Two Timings Compared to Standards in Corn

The objective of this trial was to compare Katagon (tolpyralate/nicosulfuron) to standard treatments for weed control in corn. Katagon plus atrazine applied early postemergence was as effective as any herbicide tested on the weeds present. When application timing was delayed to late postemergence, most herbicides were less effective. Early season corn injury was minor and did not persist. Although most herbicide treatments increased yields relative to the non-treated control, yields were generally best when any treatment was applied early postemergence.

Optimizing chloroacetamide application timing in dicamba-resistant cotton production systems for control of glyphosate-resistant Palmer amaranth (Amaranthus palmeri)

Abstract A chloroacetamide herbicide by application timing factorial experiment was conducted in 2017 and 2018 in Mississippi to investigate chloroacetamide use in a dicamba-based Palmer amaranth management program in cotton production. Herbicides used were S-metolachlor or acetochlor, and application timings were preemergence, preemergence followed by (fb) early postemergence, preemergence fb late postemergence, early postemergence alone, late postemergence alone, and early postemergence fb late postemergence. Dicamba was included in all preemergence applications, and dicamba plus glyphosate was included with all postemergence applications. Differences in cotton and weed response due to chloroacetamide type were minimal, and cotton injury at 14 d after late postemergence application was less than 10% for all application timings. Late-season weed control was reduced up to 30% and 53% if chloroacetamide application occurred preemergence or late postemergence only, respectively. Late-season weed densities were minimized if multiple applications were used instead of a single application. Cotton height was reduced by up to 23% if a single application was made late postemergence relative to other application timings. Chloroacetamide application at any timing except preemergence alone minimized late-season weed biomass. Yield was maximized by any treatment involving multiple applications or early postemergence alone, whereas applications preemergence or late postemergence alone resulted in up to 56% and 27% yield losses, respectively. While no yield loss was reported by delaying the first of sequential applications until early postemergence, forgoing a preemergence application is not advisable given the multiple factors that may delay timely postemergence applications such as inclement weather.

Control of glyphosate‐ and mesotrione‐resistant Palmer amaranth in glyphosate‐ and glufosinate‐resistant corn

AbstractIncreasing reports of herbicide‐resistant Palmer amaranth (Amaranthus palmeri S. Watson) pose a serious management concern for Kansas corn (Zea mays L.) producers. The objectives of this study were to evaluate various herbicide programs, including preemergence (PRE) alone, PRE followed by (fb) early postemergence (EPOST), and PRE fb late POST (LPOST) for control of glyphosate‐ and mesotrione‐resistant (GMR) Palmer amaranth in glyphosate‐ and glufosinate‐resistant corn, and their effect on crop injury, yield, and net economic return. Field experiments were conducted in 2018 and 2019 in grower fields with natural infestations of GMR Palmer amaranth near Seward in Stafford County, KS. Preemergence programs, including dicamba + thiencarbazone‐methyl + atrazine and dicamba + [atrazine, bicyclopyrone, mesotrione, S‐metolachlor (ABMS)] or dicamba + ABMS in mixtures with atrazine, mesotrione, S‐metolachlor, and metribuzin provided 89–93% control of GMR Palmer amaranth 3 wk after PRE. Preemergence fb EPOST programs provided 87–96% control of GMR Palmer amaranth at 2 wk after EPOST through 7 wk after LPOST. In comparison, PRE‐only programs provided 62–82% and PRE fb LPOST programs provided 75–86% control. The various herbicide programs resulted in greater corn grain yield ranging from 9,207 to 10,508 kg ha–1 compared with 6,056 kg ha–1 in the nontreated control. The highest net return ($1,300 ha–1) was achieved from dicamba + ABMS + atrazine applied PRE fb EPOST application of ABMS + atrazine. These results suggest that effective PRE fb EPOST herbicide programs consisting of multiple sites of actions are available and provide effective control of GMR Palmer amaranth in glyphosate‐ and glufosinate‐resistant corn.

Effect of row spacing and herbicide programs for control of glyphosate-resistant Palmer amaranth (Amaranthus palmeri) in dicamba/glyphosate-resistant soybean

AbstractGlyphosate-resistant (GR) Palmer amaranth is one of the most difficult to control weeds in soybean production fields in Nebraska and the United States. An integrated approach is required for effective management of GR Palmer amaranth. Cultural practices such as narrow row spacing might augment herbicide efficacy for management of GR Palmer amaranth. The objectives of this study were to evaluate the effect of row spacing and herbicide programs for management of GR Palmer amaranth in dicamba/glyphosate-resistant (DGR) soybean. Field experiments were conducted in a grower’s field with a uniform population of GR Palmer amaranth near Carleton, Nebraska, in 2018 and 2019. Year-by-herbicide program-by-row spacing interactions were significant for all variables; therefore, data were analyzed by year. Herbicides applied PRE controlled GR Palmer amaranth ≥95% in both years 14 d after PRE (DAPRE). Across soybean row-spacing, most PRE followed by (fb) early-POST (EPOST) herbicide programs provided 84% to 97% control of Palmer amaranth compared with most EPOST fb late-post (LPOST) programs, excluding dicamba in single and sequential applications (82% to 95% control). Mixing microencapsulated acetochlor with a POST herbicide in PRE fb EPOST herbicide programs controlled Palmer amaranth ≥93% 14 d after EPOST and ≥96% 21 d after LPOST with no effect on Palmer amaranth density. Interaction of herbicide program-by-row spacing on Palmer amaranth control was not significant; however, biomass reduction was significant at soybean harvest in 2019. The herbicide programs evaluated in this study caused no soybean injury. Due to drought conditions during a majority of the 2018 growing season, soybean yield in 2018 was reduced compared with 2019.

Spring-applied triclopyr mixtures for bermudagrass (Cynodon dactylon) suppression in Louisiana sugarcane

AbstractSugarcane infested with bermudagrass and harvested as seed cane introduces the potential for weedy propagules to reinfest fields. Research was conducted in 2018 and 2019 following sugarcane harvest for seed cane to evaluate bermudagrass management with photosystem II (PSII)- and 4-hydroxyphenylpyruvate dioxygenase (HPPD)–inhibiting herbicides applied alone or mixed with triclopyr. Combinations of diuron at 2.8 kg ha–1 with clomazone at 1.5 kg ha–1 or triclopyr at 1.1 kg ha–1 and hexazinone at 0.74 kg ha–1 with triclopyr applied early POST (EPOST) in mid-February injured bermudagrass 85% to 86%, and injury was greater than diuron or hexazinone alone (16% and 10%) in mid-March. Bermudagrass injury decreased to 45% to 56% for these combination treatments by April; however, injury differences were similar to the earlier rating. Late POST (LPOST) mid-March application of these treatments indicated similar bermudagrass injury trends when evaluated in early April. By mid-May, however, no treatment resulted in greater than 18% bermudagrass injury. Clomazone plus diuron applied LPOST resulted in 19% sugarcane injury by early April; however, all other treatments resulted in 7% sugarcane injury or less. In mid-May, a mid-April EPOST application of topramezone at 0.025 kg ha–1 plus triclopyr at 1.1 kg ha–1 resulted in 62% bermudagrass injury, which was equivalent to that observed with other topramezone rates in this combination (0.012 and 0.037 kg ha–1) (54% to 60%). Bermudagrass injury from triclopyr mixed with mesotrione (32%) or triclopyr mixed with atrazine, mesotrione, and S-metolachlor (47% to 55%) resulted in bermudagrass injury similar to that with topramezone plus triclopyr (54% to 62%). Data showed the flexibility of triclopyr when mixed with several HPPD- or PSII-inhibitor herbicides for bermudagrass management in a Louisiana sugarcane cropping system. Greater flexibility in application timing for HPPD-inhibitor herbicides than for PSII-inhibitor herbicides (diuron or hexazinone), and mixed with triclopyr, may suppress bermudagrass POST in April and May with minimal sugarcane injury.

Control of Volunteer Enlist Corn in Enlist E3 Soybean

Recent development of Enlist corn allows the use of 2,4-D choline (Enlist One), glyphosate (Roundup PowerMax), glufosinate (Liberty), and aryloxyphenoxypropionate (FOPs) herbicides for controlling grass and broadleaf weeds. However, volunteer Enlist corn plants can cause infestation in subsequent Enlist E3 soybean (resistant to 2,4-D, glyphosate, and glufosinate) in areas where a corn-soybean rotation is commonly practiced. The main objective of this research was to determine the effectiveness of cyclohexanedione (DIMs) herbicides alone or in tank-mixtures with Enlist One for Enlist corn control in Enlist E3 soybean. A field study was conducted in the 2020 growing season at the Kansas State University Agricultural Research Center (KSUARC) near Hays, KS. Enlist corn hybrid DKC62-53 was planted at 17,420 seeds/a on May 13, 2020. Enlist E3 soybean variety P30T92E was planted at 152,000 seeds/a in a perpendicular direction to corn on May 20, 2020. Herbicide treatments, including clethodim (Select Max) and sethoxydim (Poast Plus) were tested alone or in tank-mixtures with Enlist One as early POST (EPOST, 8- to 12-inch tall corn), or late postemergence (POST) (12- to 30-inch tall corn). Results indicated that Select Max applied EPOST alone provided an excellent, season-long control (95 to 99%) and highest biomass reduction (up to 100%) of volunteer Enlist corn in Enlist E3 soybean. However, volunteer corn control was significantly reduced when Enlist One was tankmixed with Poast Plus. Volunteer corn control was low to moderate (50–85%) with all late postemergence (LPOST) programs tested. Soybean grain yield did not differ among EPOST treatments (39 to 44 bu/a), while grain yield was significantly lower (~ 34 bu/a) for LPOST treatments. These results suggested that the EPOST application of Select Max and Poast Plus can effectively control volunteer Enlist corn infestation in Enlist E3soybean. However, adding Enlist One could compromise the efficacy of Poast Plus herbicide.

Pre‐plant and in‐crop herbicide programs for prickly sida control in soybean

AbstractPrickly sida (Sida spinosa L.) is emerging as a prevalent and troublesome weed in the Mid‐South glyphosate‐resistant (GR) soybean [Glycine max (L.) Merr.] cropping systems as reliance on residual herbicides has decreased. It emerges throughout the growing season and postemergence (POST) control has been reported to be variable. Combinations of residual herbicides applied pre‐plant and at‐planting followed by POST herbicides in‐crop may be needed to maximize control. This research utilized separate studies to address the value of currently available residual herbicides applied pre‐plant, at‐planting, and POST in glyphosate‐resistant soybean prickly sida management systems. At 35 days after application (DAA), prickly sida control from glyphosate plus 2,4‐D pre‐plant with flumioxazin plus chlorimuron‐ethyl, flumioxazin plus pyroxasulfone, flumioxazin plus chlorimuron‐ethyl plus thifensulfuron‐methyl, metribuzin plus chlorimuron‐ethyl or metribuzin plus sulfentrazone was 70–89% and similar among treatments. In a separate study, based on prickly sida control and density 21 days after late postemergence (LPOST) application, improvement in control was most affected by inclusion of glyphosate or glyphosate plus residual herbicides flumioxazin, chlorimuron‐ethyl, and thifensulfuron‐methyl at‐planting. Weed control was not improved when residual herbicides chlorimuron‐ethyl plus tribenuron‐methyl were included pre‐plant or when residual herbicides chlorimuron‐ethyl, s‐metolachlor, and fomesafen were applied with glyphosate POST. Late‐season prickly sida control was as high as 93% following at‐planting and POST applications that did not include residual herbicides. Soybean yield was maximized with glyphosate applied both at‐planting and POST, whether or not residual herbicides flumioxazin, chlorimuron‐ethyl, and thifensulfuron‐methyl were included at‐planting or residual herbicides chlorimuron‐ethyl, s‐metolachlor, or fomesafen were included POST. When averaged across at‐planting and POST treatments, a 10% yield increase was observed when residual herbicides chlorimuron‐ethyl and tribenuron‐methyl were applied with glyphosate plus 2,4‐D pre‐plant compared with glyphosate plus 2,4‐D alone.

Efficacy of Imiflex, Zest, and Assure II on Green Foxtail Control

Grass weeds pose a serious management challenge in grain sorghum. Recent development of three herbicide-tolerant grain sorghum technologies such as Inzen, Igrowth, and DoubleTeam will provide the opportunity for producers to use nicosulfuron (Zest), imazamox (Imiflex), and quizalofop-p-ethyl (FirstAct) for grass weed control, respectively. The main objectives of this research were to (1) determine the effectiveness of Imiflex applied preemergence (PRE) on green foxtail control in comparison to commonly used group 15 herbicides; (2) compare the efficacy of Zest, Imiflex, and Assure II applied early- or late-POST at two different rates; and (3) determine the tank-mix compatibility of Zest, Imiflex, Assure II, and Select Max (clethodim) with 2,4-D (Weedar 64) and dicamba (Clarity) on green foxtail control. Field experiments were conducted in fallow ground with a natural infestation of green foxtail at Kansas State University Agricultural Research Center in Hays, KS. PRE herbicide programs, including Imiflex, Dual II Magnum, Warrant, and Outlook were tested. Imiflex, Zest, and Assure II were tested in early- or late-postemergence (POST) timings. The early POST treatments of Imiflex, Assure II, Zest, and Select Max alone or in tank-mixture with Weedar 64 and/or Clarity were also tested in a separate study. Among PRE programs, Imiflex tested at both rates provided an excellent control (89 to 94%) of green foxtail up to 50 days after PRE (DAPRE), whereas control did not exceed more than 51% with any of the group 15 herbicides. Among early POST programs, Assure II at 10 fl oz/a provided 95% green foxtail control at 28 days after early POST (DAEPOST). Green foxtail control with early POST treatments of Imiflex, Zest, and Assure II (6 oz/a) was moderate and ranged from 77 to 83% at 28 DAEPOST. Green foxtail control with late POST treatments of Imiflex, Zest, and Assure II was inadequate and ranged from 14 to 31% at 21 days after late POST (DALPOST). In a separate study, tank-mixing Weedar 64 or Clarity with Assure II reduced the efficacy by >50% on green foxtail control compared to Assure II alone treatment. These results suggest that PRE applied Imiflex (6 or 9 oz/a) can provide excellent residual activity for early season control of green foxtail. Furthermore, Assure II applied early POST at a higher rate can provide effective control of green foxtail; however, the efficacy will significantly decline if Assure II is tank-mixed with Weedar 64 or Clarity.

Management of glyphosate-resistant Palmer amaranth (Amaranthus palmeri) in 2,4-D–, glufosinate-, and glyphosate-resistant soybean

AbstractGlyphosate-resistant (GR) Palmer amaranth is a problematic, annual broadleaf weed in soybean production fields in Nebraska and many other states in the United States. Soybean resistant to 2,4-D, glyphosate, and glufosinate (Enlist E3TM) has been developed and was first grown commercially in 2019. The objectives of this research were to evaluate the effect of herbicide programs applied PRE, PRE followed by (fb) late-POST (LPOST), and early-POST (EPOST) fb LPOST on GR Palmer amaranth control, density, and biomass reduction, soybean injury, and yield. Field experiments were conducted near Carleton, NE, in 2018, and 2019 in a grower’s field infested with GR Palmer amaranth in 2,4-D–, glyphosate-, and glufosinate-resistant soybean. Sulfentrazone + cloransulam-methyl, imazethapyr + saflufenacil + pyroxasulfone, and chlorimuron ethyl + flumioxazin + metribuzin applied PRE provided 84% to 97% control of GR Palmer amaranth compared with the nontreated control 14 d after PRE. Averaged across herbicide programs, PRE fb 2,4-D and/or glufosinate, and sequential application of 2,4-D or glufosinate applied EPOST fb LPOST resulted in 92% and 88% control of GR Palmer amaranth, respectively, compared with 62% control with PRE-only programs 14 d after LPOST. Reductions in Palmer amaranth biomass followed the same trend; however, Palmer amaranth density was reduced 98% in EPOST fb LPOST programs compared with 91% reduction in PRE fb LPOST and 76% reduction in PRE-only programs. PRE fb LPOST and EPOST fb LPOST programs resulted in an average soybean yield of 4,478 and 4,706 kg ha−1, respectively, compared with 3,043 kg ha−1 in PRE-only programs. Herbicide programs evaluated in this study resulted in no soybean injury. The results of this research illustrate that herbicide programs are available for the management of GR Palmer amaranth in 2,4-D–, glyphosate-, and glufosinate-resistant soybean.

Control of glyphosate/glufosinate-resistant volunteer corn in corn resistant to aryloxyphenoxypropionates

AbstractCorn-on-corn production systems, common in highly productive irrigated fields in South Central Nebraska, can create issues with volunteer corn management in corn fields. EnlistTM corn is a new multiple herbicide–resistance trait providing resistance to 2,4-D, glyphosate, and the aryloxyphenoxypropionate herbicides (FOPs), commonly integrated in glufosinate-resistant germplasm. The objectives of this study were to (1) evaluate ACCase-inhibiting herbicides for glyphosate/glufosinate-resistant volunteer corn control in Enlist corn and (2) evaluate the effect of ACCase-inhibiting herbicide application timing (early POST vs. late POST) on volunteer corn control, Enlist corn injury, and yield. Field experiments were conducted in 2018 and 2019 at South Central Agricultural Laboratory near Clay Center, NE. Glyphosate/glufosinate-resistant corn harvested the year prior was cross-planted at 49,000 seeds ha–1 to mimic volunteer corn in this study. After 7 to 10 d had passed, Enlist corn was planted at 91,000 seeds ha–1. Application timing of FOPs (fluazifop, quizalofop, and fluazifop/fenoxaprop) had no effect on Enlist corn injury or yield, and provided 97% to 99% control of glyphosate/glufosinate-resistant volunteer corn at 28 d after treatment (DAT). Cyclohexanediones (clethodim and sethoxydim; DIMs) and phenylpyrazolin (pinoxaden; DEN) provided 84% to 98% and 65% to 71% control of volunteer corn at 28 DAT, respectively; however, the treatment resulted in 62% to 96% Enlist corn injury and 69% to 98% yield reduction. Orthogonal contrasts comparing early-POST (30-cm-tall volunteer corn) and late-POST (50-cm-tall volunteer corn) applications of FOPs were not significant for volunteer corn control, Enlist corn injury, and yield. Fluazifop, quizalofop, and fluazifop/fenoxaprop resulted in 94% to 99% control of glyphosate/glufosinate-resistant volunteer corn with no associated Enlist corn injury or yield loss; however, quizalofop is the only labeled product as of 2020 for control of volunteer corn in Enlist corn.

Consistency in Cloud-based database systems

Cloud computing covers the large spectrum of services available on the internet. Cloud services use replication to ensure high availability. Within database replication; various copies of the same data item are stored in different sites, this situation requires managing the consistency of the multiple copies. In fact, the requirement for consistency level can be different following to application natures and other metrics; a delay of some minutes in visualizing latest posts in social networks can be tolerated, while some seconds can make a loss of a bid in an auction system. Wide variety of database management systems are used actually by cloud services. They support different level of consistency to meet the diverse needs of consistency levels. This paper draws a presentation of the main characteristics of cloud computing and data management systems and describes different consistency models. Then it discusses the most famous cloud-based database management systems from the point of view of their data and consistency models.

Abstract 071: Endothelin-1 Contributes to Vascular Dysfunction in Peri-Menopausal Women

Declines in vascular function occur early in the menopausal transition, as previously demonstrated by a reduction in endothelial function in perimenopausal women (PERI). However, the mechanisms contributing to this decline remain to be elucidated. We have previously shown that vascular impairments in postmenopausal women (POST) are due in part to endothelin-1 (ET-1). Thus, the purpose of this study is to determine if ET-1 contributes to reductions in vascular function across the stages of the menopausal transition. We hypothesized plasma ET-1 levels would be elevated across menopausal stages, and negatively associated with endothelial function. We further hypothesized that ETB receptors would contribute to impaired vascular function in PERI. Methods: We measured vascular endothelial function (flow-mediated dilation, FMD) and plasma ET-1 in 180 women classified as premenopausal (PRE, n=33, 33±7 years), early PERI (n=20, 50±3 years), late PERI (n=25, 50±4 years), early POST (n=36, 55±3 years), and late POST (n=58, 60±4 years) based on the STRAW criteria. In a separate, secondary study, we measured cutaneous microvascular endothelial function via local heating during microdialysis perfusions of lactated Ringers (control) or ETB receptor antagonist (BQ-788, 300 nM) in 6 PRE (22±2 years) and 8 PERI (50±3 years). Results: Plasma ET-1 concentration increased in a step-wise fashion across menopausal stage (PRE 5.4±1.1, early PERI 5.8±1.0, late PERI 6.1±1.6, early POST 6.4±1.6, late POST 6.4±1.5 pg/mL; P<0.01). Furthermore, there was a significant inverse correlation between plasma ET-1 and brachial artery FMD (r=0.28; P<0.001). In our secondary study, cutaneous microvascular vasodilation was lower in PERI compared to PRE (82±7 vs 92±8 %CVCmax, P <0.05). In PRE, ETB receptor blockade mediated dilation (control: 92±8 vs ETB: 83±9 %CVCmax, P <0.05), however this effect was lost in PERI (82±7 vs 92±4 %CVCmax, P <0.05). Conclusions: These data suggest that elevated ET-1 contributes to impairments in vascular endothelial function across the menopausal transition. Furthermore, the decline in endothelial function is evident in the macro- and micro- circulation during the perimenopausal transition, due in part to a loss of ETB mediated dilation.

Comparing responses of sensitive and resistant populations of Palmer amaranth (Amaranthus palmeri) and waterhemp (Amaranthus tuberculatus var. rudis) to PPO inhibitors

AbstractResistance to protoporphyrinogen oxidase (PPO) inhibitors was first observed in waterhemp in 2001 and was conferred by the deletion of a glycine residue at the 210th position (ΔGly-210) of the PPO enzyme. PPO-inhibitor resistance in Palmer amaranth was first observed in 2011, 10 years later. The objectives of this study were to directly compare PPO inhibitor responses in plants of both species with or without the ΔGly-210 mutation. Using greenhouse experiments, early (EPOST) and late (LPOST) postemergence dose responses using lactofen and fomesafen, and preemergence (PRE) dose responses using fomesafen and flumioxazin, were obtained for a sensitive and resistant population each of waterhemp and Palmer amaranth. An additional spray study confirmed each sensitive population used in the dose responses was representative of its respective species, with regards to PPO-inhibitor sensitivity. When treated at either POST timing, Palmer amaranth was more tolerant than waterhemp, and the ΔGly-210 mutation provided greater resistance in Palmer amaranth (48-fold to >3,440-fold, depending on timing and herbicide) than in waterhemp (31-fold to 123-fold). The level of tolerance in Palmer amaranth was striking; the sensitive Palmer amaranth population treated LPOST survived as well or better than the resistant waterhemp population treated EPOST. With PRE applications, response differences both between species and between resistant and sensitive populations generally were less pronounced, relative to POST applications. Collectively, this research indicates Palmer amaranth tolerance to POST-applied PPO inhibitors could have initially slowed (relative to waterhemp) evolution of resistance to these herbicides, and resistant and sensitive populations of both species are more likely to be effectively controlled with PRE rather than POST applications.