Herbicide resistant barnyardgrass in Iran and Turkey

Monarch butterfly (Danaus plexippus) decline over the past 25 years has received considerable public and scientific attention, in large part because its decline, and that of its milkweed (Asclepias spp.) host plant, have been linked to genetically modified (GM) crops and associated herbicide use. Here, we use museum and herbaria specimens to extend our knowledge of the dynamics of both monarchs and milkweeds in the United States to more than a century, from 1900 to 2016. We show that both monarchs and milkweeds increased during the early 20th century and that recent declines are actually part of a much longer-term decline in both monarchs and milkweed beginning around 1950. Herbicide-resistant crops, therefore, are clearly not the only culprit and, likely, not even the primary culprit: Not only did monarch and milkweed declines begin decades before GM crops were introduced, but other variables, particularly a decline in the number of farms, predict common milkweed trends more strongly over the period studied here.

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Establishing white clover (Trifolium repens) as a living mulch: weed control and herbicide tolerance

Weed Technology ◽

10.1017/wet.2021.45 ◽

2021 ◽

pp. 1-28

Author(s):

Nicholas T. Basinger ◽

Nicholas S. Hill

Keyword(s):

Weed Control ◽

White Clover ◽

Cover Crops ◽

Herbicide Tolerance ◽

Single Application ◽

Weed Species ◽

Living Mulch ◽

Herbicide Resistant ◽

Research And Education ◽

Weed Emergence

Abstract With the increasing focus on herbicide-resistant weeds and the lack of introduction of new modes of action, many producers have turned to annual cover crops as a tool for reducing weed populations. Recent studies have suggested that perennial cover crops such as white clover could be used as living mulch. However, white clover is slow to establish and is susceptible to competition from winter weeds. Therefore, the objective of this study was to determine clover tolerance and weed control in established stands of white clover to several herbicides. Studies were conducted in the fall and winter of 2018 to 2019 and 2019 to 2020 at the J. Phil Campbell Research and Education Center in Watkinsville, GA, and the Southeast Georgia Research and Education Center in Midville, GA. POST applications of imazethapyr, bentazon, or flumetsulam at low and high rates, or in combination with 2,4-D and 2,4-DB, were applied when clover reached 2 to 3 trifoliate stage. Six weeks after the initial POST application, a sequential application of bentazon and flumetsulam individually, and combinations of 2,4-D, 2,4-DB, and flumetsulam were applied over designated plots. Clover biomass was similar across all treatments except where it was reduced by sequential applications of 2,4-D + 2,4-DB + flumetsulam in the 2019 to 2020 season indicating that most treatments were safe for use on establishing living mulch clover. A single application of flumetsulam at the low rate or a single application of 2,4-D + 2,4-DB provided the greatest control of all weed species while minimizing clover injury when compared to the non-treated check. These herbicide options allow for control of problematic winter weeds during clover establishment, maximizing clover biomass and limiting canopy gaps that would allow for summer weed emergence.

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Effects of cereal rye seeding rate on waterhemp (Amaranthus tuberculatus) emergence and soybean growth and yield

Weed Technology ◽

10.1017/wet.2021.28 ◽

2021 ◽

pp. 1-25

Author(s):

Mandy Bish ◽

Brian Dintelmann ◽

Eric Oseland ◽

Jacob Vaughn ◽

Kevin Bradley

Keyword(s):

Crop Production ◽

Production Systems ◽

Soil Seed Bank ◽

Linear Regression Analysis ◽

Growth And Yield ◽

Seeding Rate ◽

Early Season ◽

Cereal Rye ◽

Herbicide Resistant ◽

Growing Seasons

Abstract The evolution of herbicide-resistant weeds has resulted in the necessity to integrate non-chemical control methods with chemicals for effective management in crop production systems. In soybean, control of the pigweed species, particularly herbicide-resistant waterhemp and Palmer amaranth, have become predominant concerns. Cereal rye planted as a winter cover crop can effectively suppress early-season weed emergence in soybean, including waterhemp, when planted at a rate of 123 kg ha−1. The objectives of this study were to determine the effects of different cereal rye seeding rates (0, 34, 56, 79, 110, and 123 kg ha−1) on early-season waterhemp suppression and soybean growth and yield. Soybean was planted into fall-seeded cereal rye, which was terminated within four days of soybean planting. The experiment was conducted over the 2018, 2019, and 2020 growing seasons in Columbia, Missouri. Effects of cereal rye on early-season waterhemp suppression varied by year and were most consistent at 56 kg ha−1 or higher seeding rates. Linear regression analysis of cereal rye biomass, height, or stand at soybean planting showed inverse relationships with waterhemp emergence. No adverse effects to soybean growth or yield were observed at any of the cereal rye seeding rates relative to plots that lacked cereal rye cover. Result differences among the years suggest that the successfulness of cereal rye on suppression of early-season waterhemp emergence is likely influenced by the amount of waterhemp seed present in the soil seed bank.

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Weeds Hosting the Soybean Cyst Nematode (Heterodera glycines Ichinohe): Management Implications in Agroecological Systems

Agronomy ◽

10.3390/agronomy11010146 ◽

2021 ◽

Vol 11 (1) ◽

pp. 146

Author(s):

Leonardo F. Rocha ◽

Karla L. Gage ◽

Mirian F. Pimentel ◽

Jason P. Bond ◽

Ahmad M. Fakhoury

Keyword(s):

Weed Management ◽

Soybean Cyst Nematode ◽

Heterodera Glycines ◽

Integrated Management ◽

Cropping System ◽

Cyst Nematode ◽

Weed Species ◽

Initial Inoculum ◽

Herbicide Resistant ◽

Sites Of Action

The soybean cyst nematode (SCN; Heterodera glycines Ichinohe) is a major soybean-yield-limiting soil-borne pathogen, especially in the Midwestern US. Weed management is recommended for SCN integrated management, since some weed species have been reported to be hosts for SCN. The increase in the occurrence of resistance to herbicides complicates weed management and may further direct ecological–evolutionary (eco–evo) feedbacks in plant–pathogen complexes, including interactions between host plants and SCN. In this review, we summarize weed species reported to be hosts of SCN in the US and outline potential weed–SCN management interactions. Plants from 23 families have been reported to host SCN, with Fabaceae including most host species. Out of 116 weeds hosts, 14 species have known herbicide-resistant biotypes to 8 herbicide sites of action. Factors influencing the ability of weeds to host SCN are environmental and edaphic conditions, SCN initial inoculum, weed population levels, and variations in susceptibility of weed biotypes to SCN within a population. The association of SCN on weeds with relatively little fitness cost incurred by the latter may decrease the competitive ability of the crop and increase weed reproduction when SCN is present, feeding back into the probability of selecting for herbicide-resistant weed biotypes. Therefore, proper management of weed hosts of SCN should be a focus of integrated pest management (IPM) strategies to prevent further eco–evo feedbacks in the cropping system.

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Investigating the resistance levels and mechanisms to penoxsulam and cyhalofop-butyl in barnyardgrass (Echinochloa crus-galli) from Ningxia province, China

Weed Science ◽

10.1017/wsc.2021.37 ◽

2021 ◽

pp. 1-25

Author(s):

Qian Yang ◽

Xia Yang ◽

Zichang Zhang ◽

Jieping Wang ◽

Weiguo Fu ◽

...

Keyword(s):

Herbicide Resistance ◽

Molecular Mechanisms ◽

Acetolactate Synthase ◽

Rice Fields ◽

Target Site ◽

Herbicide Resistant ◽

Susceptible Populations ◽

High Level ◽

Als Inhibitor ◽

Encoding Genes

Abstract Barnyardgrass (Echinochloa crus-galli) is a noxious grass weed which infests rice fields and causes huge crop yield losses. In this study, we collected twelve E. crus-galli populations from rice ﬁelds of Ningxia province in China and investigated the resistance levels to acetolactate synthase (ALS) inhibitor penoxsulam and acetyl-CoA carboxylase (ACCase) inhibitor cyhalofop-butyl. The results showed that eight populations exhibited resistance to penoxsulam and four populations evolved resistance to cyhalofop-butyl. Moreover, all of the four cyhalofop-butyl-resistant populations (NX3, NX4, NX6 and NX7) displayed multiple-herbicide-resistance (MHR) to both penoxsulam and cyhalofop-butyl. The alternative herbicides bispyribac-sodium, metamifop and fenoxaprop-P-ethyl cannot effectively control the MHR plants. To characterize the molecular mechanisms of resistance, we ampliﬁed and sequenced the target-site encoding genes in resistant and susceptible populations. Partial sequences of three ALS genes and six ACCase genes were examined. A Trp-574-Leu mutation was detected in EcALS1 and EcALS3 in two high-level (65.84- and 59.30-fold) penoxsulam-resistant populations NX2 and NX10, respectively. In addition, one copy (EcACC4) of ACCase genes encodes a truncated aberrant protein due to a frameshift mutation in E. crus-galli populations. None of amino acid substitutions that are known to confer herbicide resistance were detected in ALS and ACCase genes of MHR populations. Our study reveals the widespread of multiple-herbicide resistant E. crus-galli populations at Ningxia province of China that exhibit resistance to several ALS and ACCase inhibitors. Non-target-site based mechanisms are likely to be involved in E. crus-galli resistance to the herbicides, at least in four MHR populations.

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Herbicide Resistant Weed Management: Who's Resisting?

Weed Science ◽

10.1017/s0043174500088664 ◽

1997 ◽

Vol 45 (4) ◽

pp. 465-465 ◽

Cited By ~ 2

Author(s):

William E. Dyer

Keyword(s):

Weed Management ◽

Herbicide Resistant

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SULFONYLUREA HERBICIDE RESISTANT WEEDS: DISCOVERY, DISTRIBUTION, BIOLOGY, MECHANISM, AND MANAGEMENT

Herbicide Resistance in Weeds and Crops ◽

10.1016/b978-0-7506-1101-5.50012-7 ◽

1991 ◽

pp. 115-128 ◽

Cited By ~ 20

Author(s):

Donald C. Thill ◽

Carol A. Mallory-Smith ◽

Leonard L. Saari ◽

Josephine C. Cotterman ◽

Michael M. Primiani ◽

...

Keyword(s):

Sulfonylurea Herbicide ◽

Herbicide Resistant

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Corn Yield Loss Due to Volunteer Soybean

Weed Science ◽

10.1614/ws-d-16-00004.1 ◽

2016 ◽

Vol 64 (3) ◽

pp. 495-500 ◽

Cited By ~ 3

Author(s):

Jill Alms ◽

Sharon A. Clay ◽

David Vos ◽

Michael Moechnig

Keyword(s):

Loss Function ◽

Growth Stage ◽

Yield Loss ◽

Corn Yield ◽

Yield Losses ◽

Herbicide Resistant ◽

Growing Seasons ◽

Previous Season ◽

Control Volunteer ◽

Soybean Plants

The widespread adoption of glyphosate-resistant corn and soybean in cropping rotations often results in volunteer plants from the previous season becoming problem weeds that require alternative herbicides for control. Corn yield losses due to season-long volunteer soybean competition at several densities in two growing seasons were used to define a hyperbolic yield loss function. The maximum corn yield loss observed at high volunteer soybean densities was about 56%, whereas, the incremental yield loss (I) at low densities was 3.2%. Corn yield loss at low volunteer soybean densities was similar to losses reported for low densities of velvetleaf and redroot pigweed, with 10% yield loss estimated to occur at 3 to 4 volunteer soybean plants m−2. Several herbicides, including dicamba with or without diflufenzopyr applied at the V2 growth stage of volunteer soybean, provided > 90% control, demonstrating several economical options to control volunteer glyphosate-resistant soybean in glyphosate-resistant corn. Reevaluation of control recommendations may be needed with commercialization of other genetically modified herbicide-resistant soybean varieties.

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Simultaneous Adoption of Herbicide-Resistant and Conservation-Tillage Cotton Technologies

Journal of Agricultural and Applied Economics ◽

10.1017/s1074070800022665 ◽

2006 ◽

Vol 38 (3) ◽

pp. 629-643 ◽

Cited By ~ 14

Author(s):

Roland K. Roberts ◽

Burton C. English ◽

Qi Gao ◽

James A. Larson

Keyword(s):

Logit Model ◽

Conservation Tillage ◽

Bayes Theorem ◽

Cotton Production ◽

Herbicide Resistant ◽

Tillage Practices ◽

Herbicide Use ◽

Residual Herbicide ◽

The Relationship ◽

Simultaneous Adoption

If adoption of herbicide-resistant seed and adoption of conservation-tillage practices are determined simultaneously, adoption of herbicide-resistant seed could indirectly reduce soil erosion and adoption of conservation-tillage practices could indirectly reduce residual herbicide use and increase farm profits. Our objective was to evaluate the relationship between these two technologies for Tennessee cotton production. Evidence from Bayes' theorem and a two-equation logit model suggested a simultaneous relationship. Mean elasticities for acres in herbicide-resistant seed with respect to the probability of adopting conservation-tillage practices and acres in conservation-tillage practices with respect to the probability of adopting herbicide-resistant seed were 1.74 and 0.24, respectively.

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