Doveweed (Murdannia nudiflora) response to metsulfuron-methyl, trifloxysulfuron-sodium, and bentazon combinations

AbstractDoveweed is a problematic weed species in many agricultural ecosystems as well as on roadsides and rights-of-way. Effective POST chemical control options for doveweed are limited in many cropping systems. Greenhouse studies were conducted to evaluate the effectiveness of metsulfuron-methyl dose and the impact of mixtures and sequential applications of either trifloxysulfuron-sodium or bentazon with metsulfuron-methyl for doveweed control. By 14 d after the initial treatment, applying 0.04 kg ai ha−1 metsulfuron-methyl, either once or sequentially, provided 100% control of doveweed. Application of trifloxysulfuron-sodium at 0.04 kg ai ha−1 alone or in mixture with metsulfuron-methyl (0.04 kg ha−1) did not provide consistent doveweed control nor did it reduce biomass. Trifloxysulfuron-sodium applied alone at 0.08 kg ha−1 or in a mixture with metsulfuron-methyl (0.04 kg ha−1) provided consistent doveweed control (>80%). A single application of bentazon (0.56 kg ai ha−1) was ineffective at controlling doveweed. A single application of the bentazon and metsulfuron-methyl mixture (0.56 + 0.04 kg ha−1, respectively) or sequential applications of either bentazon alone (0.56 kg ha−1) or in mixture with metsulfuron-methyl (0.04 kg ha−1) provided excellent doveweed control (100%) by 35 d after treatment. Overall, single applications of metsulfuron-methyl (0.02 to 0.17 kg ha−1) or mixtures of metsulfuron-methyl with trifloxysulfuron-sodium (0.04 + 0.08 kg ha−1, respectively) or bentazon (0.04 + 0.56 kg ha−1, respectively) controlled doveweed and may be useful for enhancing the control spectrum for other weeds. Sequential applications of the bentazon and metsulfuron-methyl mixture (0.56 + 0.04 kg ha−1, respectively) provided doveweed control and are a resistance-management strategy for doveweed.

Download Full-text

Cytochrome P450 metabolic resistance (CYP6P9a) to pyrethroids imposes a fitness cost in the major African malaria vector Anopheles funestus

Heredity ◽

10.1038/s41437-020-0304-1 ◽

2020 ◽

Vol 124 (5) ◽

pp. 621-632 ◽

Cited By ~ 3

Author(s):

Magellan Tchouakui ◽

Jacob Riveron Miranda ◽

Leon M. J. Mugenzi ◽

Doumani Djonabaye ◽

Murielle J. Wondji ◽

...

Keyword(s):

Malaria Vector ◽

Management Strategy ◽

Management Strategies ◽

Resistance Management ◽

Anopheles Funestus ◽

Fitness Cost ◽

Malaria Vectors ◽

Hybrid Strain ◽

Metabolic Resistance ◽

The Impact

Abstract Metabolic resistance threatens the sustainability of pyrethroid-based malaria control interventions. Elucidating the fitness cost and potential reversal of metabolic resistance is crucial to design suitable resistance management strategies. Here, we deciphered the fitness cost associated with the CYP6P9a (P450-mediated metabolic resistance) in the major African malaria vector Anopheles funestus. Reciprocal crosses were performed between a pyrethroid susceptible (FANG) and resistant (FUMOZ-R) laboratory strains and the hybrid strains showed intermediate resistance. Genotyping the CYP6P9a-R resistance allele in oviposited females revealed that CYP6P9a negatively impacts the fecundity as homozygote susceptible mosquitoes (CYP6P9a-SS) lay more eggs than heterozygote (OR = 2.04: P = 0.01) and homozygote resistant mosquitoes. CYP6P9a also imposes a significant fitness cost on the larval development as homozygote resistant larvae (CYP6P9a-RR) developed significantly slower than heterozygote and homozygote susceptible mosquitoes (χ2 = 11.2; P = 0.0008). This fitness cost was further supported by the late pupation of homozygote resistant than susceptible mosquitoes (OR = 2.50; P < 0.01). However, CYP6P9a does not impact the longevity as no difference was observed in the life span of mosquitoes with different genotypes (χ2 = 1.6; P = 0.9). In this hybrid strain, a significant decrease of the resistant CYP6P9a-RR genotype was observed after ten generations (χ2 = 6.6; P = 0.01) suggesting a reversal of P450-based resistance in the absence of selection. This study shows that the P450-mediated metabolic resistance imposes a high fitness cost in malaria vectors supporting that a resistance management strategy based on rotation could help mitigate the impact of such resistance.

Download Full-text

Factors Affecting Weed Seed Devitalization with the Harrington Seed Destructor

Weed Science ◽

10.1017/wsc.2017.23 ◽

2017 ◽

Vol 65 (5) ◽

pp. 650-658 ◽

Cited By ~ 8

Author(s):

Breanne D. Tidemann ◽

Linda M. Hall ◽

K. Neil Harker ◽

Hugh J. Beckie

Keyword(s):

Seed Size ◽

Cropping Systems ◽

Weed Seed ◽

Weed Species ◽

Factors Affecting ◽

Weed Seeds ◽

High Control ◽

Relationship Of ◽

The Impact ◽

Levels Of Control

The Harrington Seed Destructor (HSD), a novel weed control technology, has been highly effective in Australian cropping systems. To investigate its applicability to conditions in western Canada, stationary threshing was conducted to determine the impact of weed species, seed size, seed number, chaff load, and chaff type on efficacy of seed destruction. Control varied depending on species, with a range of 97.7% to 99.8%. Sieve-sized volunteer canola seed had a linear relationship of increasing control with increasing 1,000-seed weight. However, with greater than 98% control across all tested seed weights, it is unlikely that seed size alone will significantly influence control. Consistently high levels of control were observed at all tested seed densities (10 seeds to 1 million seeds). The response of weed seed control to chaff load was quadratic, but a narrow range of consistently high control (>97%) was again observed. Chaff type had a significant effect on weed seed control (98% to 98.6%); however, seed control values in canola chaff were likely confounded by a background presence of volunteer canola. Overall, the five parameters studied statistically influence control of weed seeds with the HSD. However, small differences between treatments are unlikely to affect the biological impact of the machine, which provides high levels of control for those weed seeds that can be introduced into the harvester.

Download Full-text

Carrots and Sticks: Incentives and Regulations for Herbicide Resistance Management and Changing Behavior

Weed Science ◽

10.1614/ws-d-15-00171.1 ◽

2016 ◽

Vol 64 (SP1) ◽

pp. 627-640 ◽

Cited By ~ 13

Author(s):

Michael Barrett ◽

John Soteres ◽

David Shaw

Keyword(s):

United States ◽

Herbicide Resistance ◽

Weed Management ◽

Cropping Systems ◽

Wide Spectrum ◽

Resistance Management ◽

Herbicide Tolerance ◽

The United States ◽

Weed Species ◽

Agricultural Community

Although the problem of herbicide resistance is not new, the widespread evolution of glyphosate resistance in weed species such as Palmer amaranth (Amaranthus palmeriS. Wats.), common waterhemp (Amaranthus rudisSauer), and kochia [Kochia scoparia(L.) Schrad.] raised awareness throughout the agricultural community of herbicide resistance as a problem. Glyphosate-resistant weeds resulted in the loss of a simple, single herbicide option to control a wide spectrum of weeds that gave efficacious and economical weed management in corn (Zea maysL.), soybean [Glycine max(L.) Merr.], and cotton (Gossypium hirsutumL.) crops engineered for tolerance to this herbicide and planted over widespread areas of the South and Midwest of the United States. Beyond these crops, glyphosate is used for vegetation management in other cropping systems and in noncrop areas across the United States, and resistance to this herbicide threatens its continued utility in all of these situations. This, combined with the development of multiple herbicide-resistant weeds and the lack of commercialization of herbicides with new mechanisms of action over the past years (Duke 2012), caused the weed science community to realize that stewardship of existing herbicide resources, extending their useful life as long as possible, is imperative. Further, while additional herbicide tolerance traits are being incorporated into crops, weed management in these crops will still be based upon using existing, old, herbicide chemistries.

Download Full-text

Benchmark Study: III. Survey on Changing Herbicide Use Patterns in Glyphosate-Resistant Cropping Systems

Weed Technology ◽

10.1614/wt-d-11-00093.1 ◽

2012 ◽

Vol 26 (3) ◽

pp. 536-542 ◽

Cited By ~ 12

Author(s):

Joby M. Prince ◽

David R. Shaw ◽

Wade A. Givens ◽

Michael E. Newman ◽

Micheal D. K. Owen ◽

...

Keyword(s):

Cropping Systems ◽

Resistance Management ◽

Weed Species ◽

Use Patterns ◽

Auxin Herbicides ◽

Continued Use ◽

Selection For ◽

Level Of Selection ◽

High Level ◽

Herbicide Use

Approximately 1,300 growers from 22 states were surveyed during 2010 to determine herbicide use. Cropping systems included continuous glyphosate-resistant corn, cotton, and soybean, and various combinations of these crops and rotations with non–glyphosate-resistant crops. The most commonly used herbicide for both fall and spring applications was glyphosate followed by synthetic auxin herbicides. Herbicide application in spring was favored over application in the fall. The percentage of growers in a glyphosate-only system was as high as 69% for some cropping systems. Excluding glyphosate, the most frequently used herbicides included photosystem II, mitotic, and protoporphyrinogen oxidase inhibitors. A higher percentage of growers integrated herbicides other than glyphosate during 2010 compared with 2005. Extensive educational efforts have promoted resistance management by increasing the diversity of herbicides in glyphosate-resistant cropping systems. However, a considerable percentage of growers continued use of only glyphosate from the period of 2005 to 2010, and this practice most likely will continue to exert a high level of selection for evolved glyphosate-resistant weed species.

Download Full-text

Modeling the sustainability and economics of stacked herbicide-tolerant traits and early weed management strategy for waterhemp (Amaranthus tuberculatus) control

Weed Science ◽

10.1017/wsc.2020.6 ◽

2020 ◽

Vol 68 (2) ◽

pp. 179-185

Author(s):

Chun Liu ◽

Paul Neve ◽

Les Glasgow ◽

R. Joseph Wuerffel ◽

Micheal D. K. Owen ◽

...

Keyword(s):

Weed Management ◽

Management Strategy ◽

Resistance Management ◽

Residual Activity ◽

Genetically Modified Crops ◽

Cross Resistance ◽

Weed Species ◽

Herbicide Tolerant ◽

Amaranthus Tuberculatus ◽

Sites Of Action

AbstractDiversity is key for sustainable weed management and can be achieved via both chemical and nonchemical control tactics. Genetically modified crops with two-way or three-way stacked herbicide-tolerant traits allow use of herbicide mixtures that would otherwise be phytotoxic to the crop. Early weed management (EWM) strategies promote the use of PRE herbicides with residual activity to keep the field free of weeds early in the season for successful crop establishment. To evaluate the respective sustainability and practicality of the two chemical-based management tactics (i.e., stacked traits and EWM), we used a population model of waterhemp, Amaranthus tuberculatus (Moq.) Sauer (syn. rudis), to simulate the evolution of resistance in this key weed species in midwestern U.S. soybean [Glycine max (L.) Merr.] agroecosystems. The model tested scenarios with a varying number of herbicide sites of action (SOAs), application timings (PRE and POST), and preexisting levels of resistance. Results showed that both tactics provided opportunity for controlling resistant A. tuberculatus populations. In general, each pass over the field should include at least two effective herbicide SOAs. Nevertheless, the potential evolution of cross-resistance may void the weed control programs embraced by stacked traits and diverse herbicide SOAs. Economic calculations suggested that the diversified programs could double long-term profitability when compared to the conventional system, because of improved yield and grain quality. Ultimately, the essence of a sustainable herbicide resistance management strategy is to be proactive. Although a herbicide-dominated approach to diversifying weed management has been prevalent, the increasing presence of weed populations with multiple resistance means that finding herbicides to which weed populations are still susceptible is becoming increasingly difficult, and thus the importance of reintroducing cultural and mechanical practices to support herbicides must be recognized.

Download Full-text

Herbicide resistance in turfgrass: a chance to change the future?

Weed Technology ◽

10.1017/wet.2020.28 ◽

2020 ◽

Vol 34 (3) ◽

pp. 431-436

Author(s):

James T. Brosnan ◽

Michael W. Barrett ◽

Prasanta C. Bhowmik

Keyword(s):

Herbicide Resistance ◽

Crop Production ◽

Cropping Systems ◽

Resistance Management ◽

Human Dimensions ◽

Lessons Learned ◽

Effective Resistance ◽

Weed Species ◽

Agronomic Crops ◽

Sod Production

AbstractHerbicide resistance has for decades been an increasing problem of agronomic crops such as corn and soybean. Several weed species have evolved herbicide resistance in turfgrass systems such as golf courses, sports fields, and sod production—particularly biotypes of annual bluegrass and goosegrass. Consequences of herbicide resistance in agronomic cropping systems indicate what could happen in turfgrass if herbicide resistance becomes broader in terms of species, distribution, and mechanisms of action. The turfgrass industry must take action to develop effective resistance management programs while this problem is still relatively small in scope. We propose that lessons learned from a series of national listening sessions conducted by the Herbicide Resistance Education Committee of the Weed Science Society of America to better understand the human dimensions affecting herbicide resistance in crop production provide tremendous insight into what themes to address when developing effective resistance management programs for the turfgrass industry.

Download Full-text

Cropping systems for the Southern Great Plains of the United States as influenced by federal policy

Renewable Agriculture and Food Systems ◽

10.1079/raf2005119 ◽

2006 ◽

Vol 21 (2) ◽

pp. 77-83 ◽

Cited By ~ 3

Author(s):

Jon T. Biermacher ◽

Francis M. Epplin ◽

Kent R. Keim

Keyword(s):

Winter Wheat ◽

Federal Policy ◽

Cropping Systems ◽

The United States ◽

Weed Species ◽

North Central ◽

The North ◽

Central District ◽

Fair Act ◽

The Impact

The majority of cropland in the rain-fed region of the North Central District of Oklahoma in the US is seeded with winter wheat (Triticum aestivum) and most of it is in continuous wheat production. When annual crops are grown in monocultures, weed species and disease agents may become established and expensive to control. For many years prior to 1996, federal policy provided incentives for District producers to grow wheat and disincentives to diversify. In 1996, the Federal Agriculture Improvement and Reform (FAIR) Act (Freedom to Farm Act) was instituted, followed by the Farm Security and Rural Investment Act (FSRIA) in 2002. The objective of this study was to determine the impact of FAIR and FSRIA programs on crop diversity in the North Central District of Oklahoma. The economics of three systems, monoculture continuous winter wheat, continuous soybean (Glycine max) and a soybean–winter wheat–soybean rotation, were compared using cash market prices (CASH), CASH plus the effective loan deficiency payments (a yield-dependent subsidy) of the FAIR Act of 1996, and CASH plus the effective loan deficiency payments of the FSRIA of 2002. We found that the loan deficiency payment structure associated with FAIR provided a non-market incentive that favored soybean. However, under provisions of the 2002 FSRIA, the incentive for soybean was adjusted, resulting in greater expected returns for continuous wheat. Due to erratic weather, soybean may not be a good alternative for the region. Research is needed to identify crops that will fit in a rotation with wheat.

Download Full-text

Susceptibility of white button mushroom (agaricus bisporus lange) and its pathogens verticillium fungicola (preuss) hassebrauk and mycogone perniciosa (magnus) delacr. to fungicides

Pesticidi ◽

10.2298/pif0304237t ◽

2003 ◽

Vol 18 (4) ◽

pp. 237-244

Author(s):

Brankica Tanovic ◽

Maja Vracarevic ◽

Ivana Potocnik

Keyword(s):

Chemical Control ◽

Agaricus Bisporus ◽

Management Strategy ◽

Resistance Management ◽

Button Mushroom ◽

White Button Mushroom ◽

Verticillium Fungicola ◽

Successful Control ◽

Low Toxicity

The isolates of two mycopathogenic fungi Verticillium fungicola and Mycogone perniciosa, and a commercial isolate of white button mushroom Agaricus bisporus were tested for sensitivity to prochloraz, benomyl, and iprodione in vitro. The pathogens were isolated from the diseased mushrooms originating from mushroom farms in Vracevsnica (Gornji Milanovac) and Pozarevac in Serbia. Prochloraz and iprodione were highly toxic to both M. perniciosa and V. fungicola. The isolate of M. perniciosa was also very sensitive to benomyl, whereas the toxicity of benomyl to V.fungicola was extremely low. Among the fungicides investigated, iprodion was the most toxic and benomyl the least toxic to the isolate of white button mushroom. Chemical control of both dry and wet bubble is possible by prochloraz and iprodione. Moreover, successful control of wet bubble causal agent can be obtained by benomyl as well, due to high toxicity of this fungicide to the pathogen and low toxicity to white button mushroom. In addition, use of benomyl alternating prochloraz provides resistance management strategy providing that a given farm is free of V.fungicola population.

Download Full-text

Timing of Tillage as a Driver of Weed Communities

Weed Science ◽

10.1017/wsc.2017.26 ◽

2017 ◽

Vol 65 (4) ◽

pp. 504-514 ◽

Cited By ~ 12

Author(s):

Stéphane Cordeau ◽

Richard G. Smith ◽

Eric R. Gallandt ◽

Bryan Brown ◽

Paul Salon ◽

...

Keyword(s):

Community Structure ◽

Community Composition ◽

Management Practice ◽

Cropping Systems ◽

Block Design ◽

Growing Season ◽

Soil Tillage ◽

Weed Species ◽

Weed Communities ◽

The Impact

Tillage is a foundational management practice in many cropping systems. Although effective at reducing weed populations and preparing a crop seedbed, tillage and cultivation can also dramatically alter weed community composition. We examined the impact of soil tillage timing on weed community structure at four sites across the northeastern United States. Soil was tilled every 2 wk throughout the growing season (late April to late September 2013), and weed seedling density was quantified by species 6 wk after each tillage event. We used a randomized complete block design with four replicates for each tillage-timing treatment; a total of 196 plots were sampled. The timing of tillage was an important factor in shaping weed community composition and structure at all sites. We identified three main periods of tillage timing that resulted in similar communities. Across all sites, total weed density tended to be greatest and weed evenness tended to be lowest when soils were tilled early in the growing season. From the earliest to latest group of timings, total abundance decreased on average from 428±393 to 159±189 plants m−2, and evenness increased from 0.53±0.25 to 0.72±0.20. The effect of tillage timing on weed species richness varied by site. Our results show that tillage timing affects weed community structure, suggesting that farmers can manage weed communities and the potential for weed interference by adjusting the timing of their tillage and cropping practices.

Download Full-text

Herbicide Programs for Controlling Glyphosate-Resistant Johnsongrass (Sorghum halepense) in Glufosinate-Resistant Soybean

Weed Technology ◽

10.1614/wt-d-13-00099.1 ◽

2014 ◽

Vol 28 (1) ◽

pp. 10-18 ◽

Cited By ~ 13

Author(s):

Dennis B. Johnson ◽

Jason K. Norsworthy ◽

Robert C. Scott

Keyword(s):

Management Strategy ◽

Field Experiments ◽

Resistance Management ◽

Mechanisms Of Action ◽

Effective Resistance ◽

Sorghum Halepense ◽

Single Application ◽

Soybean Production ◽

High Level ◽

Herbicide Programs

Three field experiments were conducted in 2010 and 2012 in a soybean production field near West Memphis, AR, containing glyphosate-resistant johnsongrass. The goal of this research was to develop effective herbicide programs for glyphosate-resistant johnsongrass in glufosinate-resistant soybean. Control of the resistant johnsongrass was greater with glufosinate at 590 and 740 g ai ha−1than at 450 g ha−1. Sequential glufosinate applications were more effective than a single application, irrespective of rate. A PRE application of flumioxazin at 71 g ai ha−1immediately after planting provided no more than 26% johnsongrass control 6 wk after soybean emergence (WAE). The addition of clethodim at 136 g ai ha−1to sequential applications of glufosinate at 450 g ha−1improved control over sequentially applied glufosinate alone. Herbicide programs containing imazethapyr or imazamox in combination with glufosinate followed by clethodim plus glufosinate controlled johnsongrass at least 94% at 10 WAE and provided three distinct mechanisms of action, a highly effective resistance management strategy. Results from this research indicate that a high level of glyphosate-resistant johnsongrass control can be achieved through the use of several herbicide options in glufosinate-resistant soybean.

Download Full-text