The nature and consequence of weed spread in cropping systems

Weeds spread through movement of seeds and vegetative reproductive propagules. Pollen movement can spread weedy traits, such as herbicide resistance, between related weed and crop species. Weed seeds can spread short or long distances by natural plant dehiscence mechanisms, wind, water, animals, and man&s activities. This symposium paper is a practical review of short-distance spread of weed seeds in and between nearby arable fields and noncrop lands, examining some of the causes of spread and subsequent effects on crop production. Pollen movement, as it affects the spread of herbicide resistance, also is considered a component of short-distance weed spread. Specific weed management options can be used to reduce man-caused weed seed spread within and between nearby fields, thus reducing potential crop yield losses. Long-term management will be more difficult for weed seed spread by natural dispersal mechanisms.

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Fate of Weed Seeds after Impact Mill Processing in Midwestern and Mid-Atlantic United States

Weed Science ◽

10.1017/wsc.2019.66 ◽

2019 ◽

pp. 1-23 ◽

Cited By ~ 1

Author(s):

Lovreet S. Shergill ◽

Kreshnik Bejleri ◽

Adam Davis ◽

Steven B. Mirsky

Keyword(s):

Seed Size ◽

Weed Management ◽

Production Systems ◽

Cropping Systems ◽

Weed Seed ◽

Seed Mortality ◽

Weed Seeds ◽

Highly Effective ◽

Original Size ◽

The Impact

Abstract Harvest weed seed control (HWSC) technology such as impact mills that destroy weed seeds in seed-bearing chaff material during grain crop harvest, has been highly effective in Australian cropping systems. However, the impact mill has never been tested in soybeans and weeds common to soybean production systems in the Midwest and Mid-Atlantic US. We conducted stationary testing of Harrington Seed Destructor (HSD) impact mill and winter burial studies during 2015-2016 and 2017-2018 to determine (i) the efficacy of the impact mill to target weed seeds of seven common weeds in Midwestern and five in Mid-Atlantic US, and (ii) the fate of impact mill processed weed seeds after winter burial. The impact mill was highly effective in destroying seeds of all the species tested, with 93.5-99.8% weed seed destruction in 2015 and 85.6-100% in 2017. The weak relationships (positive or negative) between seed size and seed destruction by impact mill, and high percentage of weed seed destruction by impact mill across all seed sizes indicate that the biological or practical effect of seed size is limited. The impact mill-processed weed seeds that retained at least 50% of their original size, labeled as potentially viable seed (PVS), were buried for 90 d over winter to determine the fate of weed seeds after winter burial. At 90 d after burial (DAB), the impact mill processed PVS were significantly less viable than unprocessed control seeds, indicating that impact mill processing physically damaged the PVS and promoted seed mortality over winter. A very small fraction (< 0.4%) of the total weed seed processed by the impact mill remained viable after winter burial. The results presented here demonstrate that the impact mill is highly effective in increasing seed mortality and could potentially be used as a HWSC tactic for weed management in this region.

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Herbicide Resistance Traits in Maize and Soybean: Current Status and Future Outlook

Plants ◽

10.3390/plants8090337 ◽

2019 ◽

Vol 8 (9) ◽

pp. 337 ◽

Cited By ~ 12

Author(s):

Vijay K. Nandula

Keyword(s):

Herbicide Resistance ◽

Weed Management ◽

Cropping Systems ◽

Palmer Amaranth ◽

Current Status ◽

Weed Species ◽

Management Options ◽

Bottom Line ◽

Row Crops ◽

Resistance Traits

This article reviews, focusing on maize and soybean, previous efforts to develop nontransgenic herbicide-resistant crops (HRCs), currently available transgenic HRC traits and technologies, as well as future chemical weed management options over the horizon. Since the mid twentieth century, herbicides rapidly replaced all other means of weed management. Overreliance on ‘herbicide-only’ weed control strategies hastened evolution of HR weed species. Glyphosate-resistant (GR) crop technology revolutionized weed management in agronomic crops, but GR weeds, led by Palmer amaranth, severely reduced returns from various cropping systems and affected the bottom line of growers across the world. An additional problem was the lack of commercialization of a new herbicide mode of action since the 1990s. Auxinic HRCs offer a short-term alternative for management of GR Palmer amaranth and other weed species. New HRCs stacked with multiple herbicide resistance traits and at least two new herbicide modes of action expected to be available in the mid-2020s provide new chemical options for weed management in row crops in the next decade.

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Modeling the Impact of Harvest Weed Seed Control on Herbicide-Resistance Evolution

Weed Science ◽

10.1017/wsc.2018.9 ◽

2018 ◽

Vol 66 (3) ◽

pp. 395-403 ◽

Cited By ~ 8

Author(s):

Gayle J. Somerville ◽

Stephen B. Powles ◽

Michael J. Walsh ◽

Michael Renton

Keyword(s):

Herbicide Resistance ◽

Spatial Modeling ◽

Cropping Systems ◽

Weed Seed ◽

Future Evolution ◽

Resistance Evolution ◽

Weed Seeds ◽

Potential Benefits ◽

Evolution Of Resistance ◽

The Impact

AbstractHarvest weed seed control (HWSC) techniques have been implemented in Australian cropping systems to target and reduce the number of weed seeds entering the seedbank and thereby reduce the number of problematic weeds emerging in subsequent years to infest subsequent crops. However, the influence of HWSC on ameliorating herbicide-resistance (HR) evolution has not been investigated. This research used integrated spatial modeling to examine how the frequency and efficacy of HWSC affected the evolution of resistance to initially effective herbicides. Herbicides were, in all cases, better protected from future resistance evolution when their use was combined with annual HWSC. Outbreaks of multiple HR were very unlikely to occur and were nearly always eliminated by adding annual, efficient HWSC. The efficacy of the HWSC was important, with greater reductions in the number of resistance genes achieved with higher-efficacy HWSC. Annual HWSC was necessary to protect sequences of lower-efficacy herbicides, but HWSC could still protect herbicides if it was used less often than once per year, when the HWSC and the herbicides were highly effective. Our results highlight the potential benefits of combining HWSC with effective herbicides for controlling weed populations and reducing the future evolution of HR.

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The Role of Weed Seed Contamination in Grain Commodities as Propagule Pressure

10.21203/rs.3.rs-220124/v1 ◽

2021 ◽

Author(s):

Mafumi Ikeda ◽

Takeshi Nishi ◽

Motoaki Asai ◽

Takashi Muranaka ◽

Akihiro Konuma ◽

...

Keyword(s):

Weed Management ◽

Propagule Pressure ◽

Abundant Species ◽

Contamination Rate ◽

Weed Seed ◽

Weed Species ◽

Management Options ◽

Major Pathway ◽

Weed Seeds ◽

Unintentional Introduction

Abstract The international grain trade is a major pathway for the introduction of alien plants because grain commodities can be contaminated with various weed seeds. To evaluate how alien weed seeds derived from imported grain commodities affect local vegetation in international trading ports, we conducted a vegetation survey on a set of grain landing ports and non-grain landing ports in nine regions throughout Japan to compare the vegetation between these two types of ports. We also surveyed weed seed contamination of wheat imported into Japan, and the contamination rate was calculated for each species based on our survey and previous studies on weed seed contamination. The vegetation clearly differed between the grain landing ports and the non-grain ports. In the grain landing ports, alien species were more abundant than in non-grain landing ports. All indicator species of the grain landing ports were reported to be contaminants in grain commodities. Furthermore, there was a tendency for the more abundant species at the grain landing ports to show higher contamination rates in grain commodities. These results indicate that contaminant seeds spill from imported grain in grain landing ports, and highly contaminated species are likely to become established. We clearly show that weed seed contamination in grain commodities plays an important role in propagule pressure. Gathering information about the prevalence of weeds in grain-exporting countries and monitoring the weed species composition in imported grain commodities is becoming increasingly important for predicting the unintentional introduction of troublesome weeds and identifying effective weed management options.

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Managing Wicked Herbicide-Resistance: Lessons from the Field

Weed Technology ◽

10.1017/wet.2018.49 ◽

2018 ◽

Vol 32 (4) ◽

pp. 475-488 ◽

Cited By ~ 10

Author(s):

Jill Schroeder ◽

Michael Barrett ◽

David R. Shaw ◽

Amy B. Asmus ◽

Harold Coble ◽

...

Keyword(s):

United States ◽

Herbicide Resistance ◽

Weed Management ◽

Crop Production ◽

Production Systems ◽

Cropping Systems ◽

Resistance Management ◽

Interdisciplinary Approach ◽

The United States ◽

The Many

AbstractHerbicide resistance is ‘wicked’ in nature; therefore, results of the many educational efforts to encourage diversification of weed control practices in the United States have been mixed. It is clear that we do not sufficiently understand the totality of the grassroots obstacles, concerns, challenges, and specific solutions needed for varied crop production systems. Weed management issues and solutions vary with such variables as management styles, regions, cropping systems, and available or affordable technologies. Therefore, to help the weed science community better understand the needs and ideas of those directly dealing with herbicide resistance, seven half-day regional listening sessions were held across the United States between December 2016 and April 2017 with groups of diverse stakeholders on the issues and potential solutions for herbicide resistance management. The major goals of the sessions were to gain an understanding of stakeholders and their goals and concerns related to herbicide resistance management, to become familiar with regional differences, and to identify decision maker needs to address herbicide resistance. The messages shared by listening-session participants could be summarized by six themes: we need new herbicides; there is no need for more regulation; there is a need for more education, especially for others who were not present; diversity is hard; the agricultural economy makes it difficult to make changes; and we are aware of herbicide resistance but are managing it. The authors concluded that more work is needed to bring a community-wide, interdisciplinary approach to understanding the complexity of managing weeds within the context of the whole farm operation and for communicating the need to address herbicide resistance.

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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.

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Herbicide-Resistant Weed Seeds Contaminate Grain Sown in the Western Australian Grainbelt

Weed Science ◽

10.1614/ws-d-09-00082.1 ◽

2010 ◽

Vol 58 (4) ◽

pp. 466-472 ◽

Cited By ~ 34

Author(s):

Pippa J. Michael ◽

Mechelle J. Owen ◽

Stephen B. Powles

Keyword(s):

Herbicide Resistance ◽

Weed Management ◽

Farming Systems ◽

Wild Oat ◽

Wild Radish ◽

Crop Species ◽

Weed Seeds ◽

Rigid Ryegrass ◽

Western Australian ◽

Crop Seed

Preventing the introduction of weeds into the farming system through sowing of clean seeds is an essential component of weed management. The weed seed contamination of cleaned grain and herbicide resistance levels of the recovered weed seeds were examined in a study conducted across 74 farms in the Western Australian grainbelt. Most farmers grew and conserved their own crop seed. The majority of cleaned samples had some level of seed contamination from 11 foreign weed and volunteer crop species, with an average of 62 seeds 10 kg−1grain, substantially higher than the 28 seeds 10 kg−1grain expected by farmers. The most common weed contaminants across all samples were rigid ryegrass, wild radish, brome, and wild oat. When categorized by crop type, rigid ryegrass was the most frequent contaminant of cereal crops (barley and wheat), however wild radish was the most frequent contaminant of lupin crops. Uncleaned crop seed samples had almost 25 times more contamination than cleaned crop seed. Herbicide resistance was highly prevalent within rigid ryegrass populations recovered from cleaned grain except for glyphosate, which controlled all populations tested. Some resistance was also found in wild radish and wild oat populations; however, brome was susceptible to fluazifop. This study has shown that farmers are unknowingly introducing weed seeds into their farming systems during crop seeding, many of which have herbicide resistance.

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Improving the Management of Parthenium hysterophorus to Enhance Okra Production through the Application of Chemicals, Adjuvants and Plant Extract Blends in Pakistan

Caraka Tani Journal of Sustainable Agriculture ◽

10.20961/carakatani.v36i1.48215 ◽

2021 ◽

Vol 36 (1) ◽

pp. 165

Author(s):

Muhammad Adnan ◽

Muhammad Sikander Hayyat ◽

Qaisar Mumtaz ◽

Muhammad Ehsan Safdar ◽

Fazal Ur Rehman ◽

...

Keyword(s):

Plant Extracts ◽

Weed Management ◽

Crop Production ◽

Cropping Systems ◽

Integrated Approach ◽

General Information ◽

Parthenium Hysterophorus ◽

Effective Control ◽

Management Options ◽

Allelopathic Potential

Vegetables are consequently experiencing great yield losses due to weed infestation. Weed management is extremely important for sustainable crop production in all cropping systems. This review paper aimed to provide general information and alternative recommendations for the management of Parthenium hysterophorus weed by chemicals, adjuvants and plant extracts in okra. Different strategies have been used to control parthenium, but no single management solution is sufficient to handle parthenium; hence, different management options need to be combined. Only an integrated approach will achieve effective control over this weed. In areas where parthenium natural enemies are absent, chemical control is an important method of managing this weed. In the control of this plant, the use of chemical herbicides such as chlorimuron ethyl, glyphosate, atrazine, ametryn, bromoxynil and metsulfuron are considered to be efficient. Moreover, various plants have allelopathic potential and attempts have been made to use them in parthenium control. Three allelopathic grasses, namely, Achyranthes aspera, Syzygium cumini and Acacia nilotica are able to minimize the plant growth and inhibit early seedling growth of exotic weed P. hysterophorus. The results recommend that the control of parthenium in okra and other summer vegetables using chemical herbicides with single and combination mode of action is still effective compared to the use of plant extracts. The use of herbicides by adding adjuvants has the potential to minimize the use of excessive herbicides.

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The Pitfalls of Relating Weeds, Herbicide Use, and Crop Yield: Don't Fall Into the Trap! A Critical Review

Frontiers in Agronomy ◽

10.3389/fagro.2020.615470 ◽

2020 ◽

Vol 2 ◽

Author(s):

Nathalie Colbach ◽

Sandrine Petit ◽

Bruno Chauvel ◽

Violaine Deytieux ◽

Martin Lechenet ◽

...

Keyword(s):

Crop Yield ◽

Weed Management ◽

Crop Production ◽

Yield Loss ◽

Crop Yields ◽

Cropping Systems ◽

Crop Productivity ◽

Arable Farming ◽

Herbicide Use ◽

The Impact

The growing recognition of the environmental and health issues associated to pesticide use requires to investigate how to manage weeds with less or no herbicides in arable farming while maintaining crop productivity. The questions of weed harmfulness, herbicide efficacy, the effects of herbicide use on crop yields, and the effect of reducing herbicides on crop production have been addressed over the years but results and interpretations often appear contradictory. In this paper, we critically analyze studies that have focused on the herbicide use, weeds and crop yield nexus. We identified many inconsistencies in the published results and demonstrate that these often stem from differences in the methodologies used and in the choice of the conceptual model that links the three items. Our main findings are: (1) although our review confirms that herbicide reduction increases weed infestation if not compensated by other cultural techniques, there are many shortcomings in the different methods used to assess the impact of weeds on crop production; (2) Reducing herbicide use rarely results in increased crop yield loss due to weeds if farmers compensate low herbicide use by other efficient cultural practices; (3) There is a need for comprehensive studies describing the effect of cropping systems on crop production that explicitly include weeds and disentangle the impact of herbicides from the effect of other practices on weeds and on crop production. We propose a framework that presents all the links and feed-backs that must be considered when analyzing the herbicide-weed-crop yield nexus. We then provide a number of methodological recommendations for future studies. We conclude that, since weeds are causing yield loss, reduced herbicide use and maintained crop productivity necessarily requires a redesign of cropping systems. These new systems should include both agronomic and biodiversity-based levers acting in concert to deliver sustainable weed management.

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iHSD Mill Efficacy on the Seeds of Australian Cropping System Weeds

Weed Technology ◽

10.1017/wet.2017.95 ◽

2017 ◽

Vol 32 (2) ◽

pp. 103-108 ◽

Cited By ~ 6

Author(s):

Michael J. Walsh ◽

John C. Broster ◽

Stephen B. Powles

Keyword(s):

Moisture Content ◽

Crop Production ◽

Production Systems ◽

Cropping Systems ◽

Cropping System ◽

High Efficacy ◽

Weed Seed ◽

Rigid Ryegrass ◽

Mill Speed ◽

Wheat Chaff

AbstractIn Australia, widespread evolution of multi-resistant weed populations has driven the development and adoption of harvest weed seed control (HWSC). However, due to incompatibility of commonly used HWSC systems with highly productive conservation cropping systems, better HWSC systems are in demand. This study aimed to evaluate the efficacy of the integrated Harrington Seed Destructor (iHSD) mill on the seeds of Australia’s major crop weeds during wheat chaff processing. Also examined were the impacts of chaff type and moisture content on weed seed destruction efficacy. Initially, the iHSD mill speed of 3,000 rpm was identified as the most effective at destroying rigid ryegrass seeds present in wheat chaff. Subsequent testing determined that the iHSD mill was highly effective (>95% seed kill) on all Australian crop weeds examined. Rigid ryegrass seed kill was found to be highest for lupin chaff and lowest in barley, with wheat and canola chaff intermediate. Similarly, wheat chaff moisture reduced rigid ryegrass seed kill when moisture level exceeded 12%. The broad potential of the iHSD mill was evident, in that the reductions in efficacy due to wide-ranging differences in chaff type and moisture content were relatively small (≤10%). The results from these studies confirm the high efficacy and widespread suitability of the iHSD for use in Australian crop production systems. Additionally, as this system allows the conservation of all harvest residues, it is the best HWSC technique for conservation cropping systems.

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