Conyza bonariensis (flax-leaf fleabane) resistant to both glyphosate and ALS inhibiting herbicides innorth-eastern Victoria

Conyza bonariensis (L.) Cronq. (syn. of Erigeron bonariensis L.) is a difficult-to-control summer weed species in the cropping belt of south-eastern Australia. Herbicide resistance may be affecting the ability to control C. bonariensis in the agricultural region of north-eastern Victoria; therefore, a survey was conducted to evaluate resistance to herbicides from several mode-of-action groups. Of the populations collected, 40% were resistant to glyphosate at 1080 g ha–1. Chlorsulfuron failed to control any of the populations collected. Further research identified multiple herbicide resistance to glyphosate, chlorsulfuron, metsulfuron-methyl and sulfometuron-methyl in five of nine populations fully characterised. Resistance was not found to 2,4-D, clopyralid or paraquat. There was no correlation between prevailing land use and the frequency of glyphosate-resistant populations, suggesting that resistance had been selected in multiple production systems. The high frequency of resistance could explain the difficulty experienced in controlling C. bonariensis across north-eastern Victoria and demonstrates the importance of integrated weed management to manage this weed.

Download Full-text

Weed Problems in Uruguayan Agriculture: Evolution and Current Situation

Outlooks on Pest Management ◽

10.1564/v32_oct_05 ◽

2021 ◽

Vol 32 (5) ◽

pp. 203-207

Author(s):

M. Alejandro Garcia ◽

Lucia V. Meneses ◽

Tiago Edu Kaspary

Keyword(s):

Weed Management ◽

Agricultural Production ◽

Production Systems ◽

Integrated Weed Management ◽

Zero Tillage ◽

Weed Species ◽

Management Tools ◽

Herbicide Resistant ◽

Species Frequencies ◽

Agricultural Production Systems

Uruguayan agriculture has undergone dramatic changes in the last 50 years driven by the adoption of new agricultural production systems that incorporate zero tillage and herbicide resistant crops. This has resulted in a shift in weed species frequencies and the dispersion of introduced herbicide resistant weed populations. Finally, integrated weed management tools are being developed by research and extension services to manage herbicide-resistant (HR) weeds better and to reduce environmental impact of herbicides.

Download Full-text

A New Approach to Weed Management to Mitigate Herbicide Resistance in Argentina

Weed Science ◽

10.1614/ws-d-16-00016.1 ◽

2016 ◽

Vol 64 (SP1) ◽

pp. 641-648 ◽

Cited By ~ 6

Author(s):

Claudio Rubione ◽

Sarah M. Ward

Keyword(s):

Herbicide Resistance ◽

Weed Management ◽

Integrated Weed Management ◽

National Committee ◽

Weed Species ◽

Corn Production ◽

Public And Private ◽

Herbicide Resistant ◽

Crop Varieties ◽

Export Taxes

The evolution of herbicide-resistant weeds is a major concern in the corn- and soybean-producing Pampas region of Argentina, where growers predominantly plant glyphosate-resistant crop varieties and depend heavily on glyphosate for weed control. Currently, 16 weed species in Argentina are resistant to one or more of three different herbicide mechanisms of action, and resistant weed populations continue to increase, posing a serious threat to agricultural production. Implementation of integrated weed management to address herbicide resistance faces significant barriers in Argentina, especially current land ownership and rental patterns in the Pampas. More than 60% of Pampas cropland is rented to tenants for periods that rarely exceed 1 yr, resulting in crop rotation being largely abandoned, and crop export taxes and quotas have further discouraged wheat and corn production in favor of continuous soybean production. In this paper we discuss ways to facilitate new approaches to weed management in Argentina, including legal and economic reforms and the formation of a national committee of stakeholders from public and private agricultural sectors.

Download Full-text

Droplet Size Impact on Efficacy of a Dicamba-plus-Glyphosate Mixture

Weed Technology ◽

10.1017/wet.2018.118 ◽

2019 ◽

Vol 33 (1) ◽

pp. 66-74 ◽

Cited By ~ 5

Author(s):

Thomas R. Butts ◽

Chase A. Samples ◽

Lucas X. Franca ◽

Darrin M. Dodds ◽

Daniel B. Reynolds ◽

...

Keyword(s):

Droplet Size ◽

Herbicide Resistance ◽

Weed Management ◽

Integrated Weed Management ◽

Weed Species ◽

Application Process ◽

Biological Efficacy ◽

Particle Drift ◽

Drift Potential ◽

Droplet Sizes

AbstractChemical weed control remains a widely used component of integrated weed management strategies because of its cost-effectiveness and rapid removal of crop pests. Additionally, dicamba-plus-glyphosate mixtures are a commonly recommended herbicide combination to combat herbicide resistance, specifically in recently commercially released dicamba-tolerant soybean and cotton. However, increased spray drift concerns and antagonistic interactions require that the application process be optimized to maximize biological efficacy while minimizing environmental contamination potential. Field research was conducted in 2016, 2017, and 2018 across three locations (Mississippi, Nebraska, and North Dakota) for a total of six site-years. The objectives were to characterize the efficacy of a range of droplet sizes [150 µm (Fine) to 900 µm (Ultra Coarse)] using a dicamba-plus-glyphosate mixture and to create novel weed management recommendations utilizing pulse-width modulation (PWM) sprayer technology. Results across pooled site-years indicated that a droplet size of 395 µm (Coarse) maximized weed mortality from a dicamba-plus-glyphosate mixture at 94 L ha–1. However, droplet size could be increased to 620 µm (Extremely Coarse) to maintain 90% of the maximum weed mortality while further mitigating particle drift potential. Although generalized droplet size recommendations could be created across site-years, optimum droplet sizes within each site-year varied considerably and may be dependent on weed species, geographic location, weather conditions, and herbicide resistance(s) present in the field. The precise, site-specific application of a dicamba-plus-glyphosate mixture using the results of this research will allow applicators to more effectively utilize PWM sprayers, reduce particle drift potential, maintain biological efficacy, and reduce the selection pressure for the evolution of herbicide-resistant weeds.

Download Full-text

Herbicide-Resistant Weeds: Management Tactics and Practices

Weed Technology ◽

10.1614/wt-05-084r1.1 ◽

2006 ◽

Vol 20 (3) ◽

pp. 793-814 ◽

Cited By ~ 205

Author(s):

Hugh J. Beckie

Keyword(s):

Herbicide Resistance ◽

Weed Management ◽

Management Practices ◽

Cropping Systems ◽

Integrated Weed Management ◽

Weed Species ◽

Herbicide Resistant ◽

Application Rates ◽

Selection For ◽

Reactive Management

In input-intensive cropping systems around the world, farmers rarely proactively manage weeds to prevent or delay the selection for herbicide resistance. Farmers usually increase the adoption of integrated weed management practices only after herbicide resistance has evolved, although herbicides continue to be the dominant method of weed control. Intergroup herbicide resistance in various weed species has been the main impetus for changes in management practices and adoption of cropping systems that reduce selection for resistance. The effectiveness and adoption of herbicide and nonherbicide tactics and practices for the proactive and reactive management of herbicide-resistant (HR) weeds are reviewed. Herbicide tactics include sequences and rotations, mixtures, application rates, site-specific application, and use of HR crops. Nonherbicide weed-management practices or nonselective herbicides applied preplant or in crop, integrated with less-frequent selective herbicide use in diversified cropping systems, have mitigated the evolution, spread, and economic impact of HR weeds.

Download Full-text

Survey of weed flora and management relative to cropping practices in the north-eastern grain region of Australia

Australian Journal of Experimental Agriculture ◽

10.1071/ea05141 ◽

2007 ◽

Vol 47 (1) ◽

pp. 57 ◽

Cited By ~ 43

Author(s):

V. A. Osten ◽

S. R. Walker ◽

A. Storrie ◽

M. Widderick ◽

P. Moylan ◽

...

Keyword(s):

Weed Management ◽

Management Practices ◽

Postal Survey ◽

Integrated Weed Management ◽

The North ◽

South Wales ◽

Eastern Australia ◽

North Eastern ◽

Weed Flora ◽

Rapistrum Rugosum

The main weeds and weed management practices undertaken in broad acre dryland cropping areas of north-eastern Australia have been identified. The information was collected in a comprehensive postal survey of both growers and agronomists from Dubbo in New South Wales (NSW) through to Clermont in central Queensland, where 237 surveys were returned. A very diverse weed flora of 105 weeds from 91 genera was identified for the three cropping zones within the region (central Queensland, southern Queensland and northern NSW). Twenty-three weeds were common to all cropping zones. The major common weeds were Sonchus oleraceus, Rapistrum rugosum, Echinochloa spp. and Urochloa panicoides. The main weeds were identified for both summer and winter fallows, and sorghum, wheat and chickpea crops for each of the zones, with some commonality as well as floral uniqueness recorded. More genera were recorded in the fallows than in crops, and those in summer fallows exceeded the number in winter. Across the region, weed management relied heavily on herbicides. In fallows, glyphosate and mixes with glyphosate were very common, although the importance of the glyphosate mix partner differed among the cropping zones. Use and importance of pre-emergence herbicides in-crop varied considerably among the zones. In wheat, more graminicides were used in northern NSW than in southern Queensland, and virtually none were used in central Queensland, reflecting the differences in winter grass weed flora across the region. Atrazine was the major herbicide used in sorghum, although metolachlor was also used predominantly in northern NSW. Fallow and inter-row cultivation were used more often in the southern areas of the region. Grazing of fallows was more prominent in northern NSW. High crop seeding rates were not commonly recorded indicating that growers are not using crop competition as a tool for weed management. Although many management practices were recorded overall, few growers were using integrated weed management, and herbicide resistance has been and continues to be an issue for the region.

Download Full-text

Spatial Modelling of Within-Field Weed Populations; a Review

Agronomy ◽

10.3390/agronomy10071044 ◽

2020 ◽

Vol 10 (7) ◽

pp. 1044

Author(s):

Gayle J. Somerville ◽

Mette Sønderskov ◽

Solvejg Kopp Mathiassen ◽

Helen Metcalfe

Keyword(s):

Herbicide Resistance ◽

Weed Management ◽

Control Strategies ◽

Management Strategies ◽

Spatial Modelling ◽

Integrated Weed Management ◽

Weed Species ◽

Invasive Weed ◽

Temporal Models ◽

Spatio Temporal

Concerns around herbicide resistance, human risk, and the environmental impacts of current weed control strategies have led to an increasing demand for alternative weed management methods. Many new weed management strategies are under development; however, the poor availability of accurate weed maps, and a lack of confidence in the outcomes of alternative weed management strategies, has hindered their adoption. Developments in field sampling and processing, combined with spatial modelling, can support the implementation and assessment of new and more integrated weed management strategies. Our review focuses on the biological and mathematical aspects of assembling within-field weed models. We describe both static and spatio-temporal models of within-field weed distributions (including both cellular automata (CA) and non-CA models), discussing issues surrounding the spatial processes of weed dispersal and competition and the environmental and anthropogenic processes that affect weed spatial and spatio-temporal distributions. We also examine issues surrounding model uncertainty. By reviewing the current state-of-the-art in both static and temporally dynamic weed spatial modelling we highlight some of the strengths and weaknesses of current techniques, together with current and emerging areas of interest for the application of spatial models, including targeted weed treatments, economic analysis, herbicide resistance and integrated weed management, the dispersal of biocontrol agents, and invasive weed species.

Download Full-text

Upgrading the RIM Model for Improved Support of Integrated Weed Management Extension Efforts in Cropping Systems

Weed Technology ◽

10.1614/wt-d-14-00020.1 ◽

2014 ◽

Vol 28 (4) ◽

pp. 703-720 ◽

Cited By ~ 13

Author(s):

Myrtille Lacoste ◽

Stephen Powles

Keyword(s):

Herbicide Resistance ◽

Weed Management ◽

Cropping Systems ◽

Integrated Management ◽

Integrated Weed Management ◽

Weed Species ◽

Management Options ◽

Rigid Ryegrass ◽

And Control

RIM, or “Ryegrass Integrated Management,” is a user-friendly weed management software that integrates long-term economics. As a model-based decision support system, RIM enables users to easily build 10-year cropping scenarios and evaluate the impacts of management choices on annual rigid ryegrass populations and long-term profitability. Best used in a workshop format to enable learning through interactions, RIM can provide insights for the sustainable management of ryegrass through “what-if” scenarios in regions facing herbicide resistance issues. The upgrade of RIM is presented, with changes justified from an end-user perspective. The implementation of the model in a new, intuitive software format is presented, as well as the revision, update, and documentation of over 40 management options. Enterprises, establishment systems, and control options were redefined to represent current practices, with the notable inclusion of customizable herbicide options and techniques for weed seed control at harvest. Several examples of how RIM can be used with farmers to demonstrate the benefits of adopting recommended practices for managing or delaying the onset of herbicide resistance are presented. Originally designed for the dryland broadacre systems of the Australian southern grainbelt, RIM's underlying modeling was restructured to facilitate future updates and adaptation to other weed species and cropping regions.

Download Full-text

Management of Pigweed (Amaranthusspp.) in Glufosinate-Resistant Soybean in the Midwest and Mid-South

Weed Technology ◽

10.1614/wt-d-15-00076.1 ◽

2016 ◽

Vol 30 (2) ◽

pp. 355-365 ◽

Cited By ~ 14

Author(s):

Thomas R. Butts ◽

Jason K. Norsworthy ◽

Greg R. Kruger ◽

Lowell D. Sandell ◽

Bryan G. Young ◽

...

Keyword(s):

Grain Yield ◽

Weed Management ◽

Production Systems ◽

Management Strategies ◽

Integrated Weed Management ◽

Weed Species ◽

Seeding Rate ◽

Row Width ◽

Narrow Row ◽

Sites Of Action

Pigweeds are among the most abundant and troublesome weed species across Midwest and mid-South soybean production systems because of their prolific growth characteristics and ability to rapidly evolve resistance to several herbicide sites of action. This has renewed interest in diversifying weed management strategies by implementing integrated weed management (IWM) programs to efficiently manage weeds, increase soybean light interception, and increase grain yield. Field studies were conducted across 16 site-years to determine the effectiveness of soybean row width, seeding rate, and herbicide strategy as components of IWM in glufosinate-resistant soybean. Sites were grouped according to optimum adaptation zones for soybean maturity groups (MGs). Across all MG regions, pigweed density and height at the POST herbicide timing, and end-of-season pigweed density, height, and fecundity were reduced in IWM programs using a PRE followed by (fb) POST herbicide strategy. Furthermore, a PRE fb POST herbicide strategy treatment increased soybean cumulative intercepted photosynthetically active radiation (CIPAR) and subsequently, soybean grain yield across all MG regions. Soybean row width and seeding rate manipulation effects were highly variable. Narrow row width (≤ 38 cm) and a high seeding rate (470,000 seeds ha−1) reduced end-of-season height and fecundity variably across MG regions compared with wide row width (≥ 76 cm) and moderate to low (322,000 to 173,000 seeds ha−1) seeding rates. However, narrow row widths and high seeding rates did not reduce pigweed density at the POST herbicide application timing or at soybean harvest. Across all MG regions, soybean CIPAR increased as soybean row width decreased and seeding rate increased; however, row width and seeding rate had variable effects on soybean yield. Furthermore, soybean CIPAR was not associated with end-of-season pigweed growth and fecundity. A PRE fb POST herbicide strategy was a necessary component for an IWM program as it simultaneously managed pigweeds, increased soybean CIPAR, and increased grain yield.

Download Full-text

A Review of Herbicide Resistance in Iran

Weed Science ◽

10.1614/ws-d-15-00139.1 ◽

2016 ◽

Vol 64 (4) ◽

pp. 551-561 ◽

Cited By ~ 10

Author(s):

Javid Gherekhloo ◽

Mostafa Oveisi ◽

Eskandar Zand ◽

Rafael De Prado

Keyword(s):

Herbicide Resistance ◽

Crop Production ◽

Arable Land ◽

Wheat Crop ◽

Wild Oat ◽

Weed Species ◽

Wild Mustard ◽

Development Of Resistance ◽

Resistance To Herbicides ◽

Continuous Use

Continuous use of herbicides has triggered a phenomenon called herbicide resistance. Nowadays, herbicide resistance is a worldwide problem that threatens sustainable agriculture. A study of over a decade on herbicides in Iran has revealed that herbicide resistance has been occurring since 2004 in some weed species. Almost all the results of these studies have been published in national scientific journals and in conference proceedings on the subject. In the current review, studies on herbicide resistance in Iran were included to provide a perspective of developing weed resistance to herbicides for international scientists. More than 70% of arable land in Iran is given over to cultivation of wheat, barley, and rice; wheat alone covers nearly 52%. Within the past 40 years, 108 herbicides from different groups of modes of action have been registered in Iran, of which 28 are for the selective control of weeds in wheat and barley. Major resistance to ACCase-inhibiting herbicides has been shown in some weed species, such as winter wild oat, wild oat, littleseed canarygrass, hood canarygrass, and rigid ryegrass. With respect to the broad area of wheat crop production and continuous use of herbicides with the sole mechanism of action of ACCase inhibition, the provinces of West Azerbaijan, Tehran, Khorasan, Isfahan, Markazi, and Semnan are at risk of resistance development. In addition, because of continuous long-term use of tribenuron-methyl, resistance in broadleaf species is also being developed. Evidence has recently shown resistance of turnipweed and wild mustard populations to this herbicide. Stable monitoring of fields in doubtful areas and providing good education and training for technicians and farmers to practice integrated methods would help to prevent or delay the development of resistance to herbicides.

Download Full-text

Alternatives to Atrazine for Weed Management in Processing Sweet Corn

Weed Science ◽

10.1614/ws-d-16-00001.1 ◽

2016 ◽

Vol 64 (3) ◽

pp. 531-539 ◽

Cited By ~ 3

Author(s):

Zubeyde Filiz Arslan ◽

Martin M. Williams ◽

Roger Becker ◽

Vincent A. Fritz ◽

R. Ed Peachey ◽

...

Keyword(s):

Weed Control ◽

Weed Management ◽

Sweet Corn ◽

Crop Yields ◽

Production Systems ◽

Field Trials ◽

Management Systems ◽

Weed Species ◽

Application Timing ◽

Production Areas

Atrazine has been the most widely used herbicide in North American processing sweet corn for decades; however, increased restrictions in recent years have reduced or eliminated atrazine use in certain production areas. The objective of this study was to identify the best stakeholder-derived weed management alternatives to atrazine in processing sweet corn. In field trials throughout the major production areas of processing sweet corn, including three states over 4 yr, 12 atrazine-free weed management treatments were compared to three standard atrazine-containing treatments and a weed-free check. Treatments varied with respect to herbicide mode of action, herbicide application timing, and interrow cultivation. All treatments included a PRE application of dimethenamid. No single weed species occurred across all sites; however, weeds observed in two or more sites included common lambsquarters, giant ragweed, morningglory species, velvetleaf, and wild-proso millet. Standard treatments containing both atrazine and mesotrione POST provided the most efficacious weed control among treatments and resulted in crop yields comparable to the weed-free check, thus demonstrating the value of atrazine in sweet corn production systems. Timely interrow cultivation in atrazine-free treatments did not consistently improve weed control. Only two atrazine-free treatments consistently resulted in weed control and crop yield comparable to standard treatments with atrazine POST: treatments with tembotrione POST either with or without interrow cultivation. Additional atrazine-free treatments with topramezone applied POST worked well in Oregon where small-seeded weed species were prevalent. This work demonstrates that certain atrazine-free weed management systems, based on input from the sweet corn growers and processors who would adopt this technology, are comparable in performance to standard atrazine-containing weed management systems.

Download Full-text