Weed Science Research Research Articles

Broadening the scope of weed research: Integrating ecological theories to propel weed management

AbstractWeed science plays a vital role in mitigating the negative impacts of weeds in agriculture and natural ecosystems. However, the field has received criticism for its limited theoretical foundation and excessive focus on phenomenological and narrow scope. Our contention is that weed science needs to integrate more ecological theories to foster a deeper understanding of weed ecology, biology, and management. By embracing theoretical frameworks, weed science can enhance its ability to predict and explain weed dynamics, identify underlying mechanisms, and develop sustainable management strategies. This insight emphasizes the advantages of integrating theoretical approaches and offers practical recommendations to integrate ecological theory effectively into weed science research.

IMPACT OF SOIL STERILIZATION FROM DIFFERENT LOCATIONS, WHEAT SEEDS CLEANING AND THEIR INTERACTIONS ON WEED CONTROL, AND YIELD AND YIELD COMPONENTS

IMPACT OF SOIL STERILIZATION FROM DIFFERENT LOCATIONS, WHEAT SEEDS CLEANING AND THEIR INTERACTIONS ON WEED CONTROL, AND YIELD AND YIELD COMPONENTS

Weed science research achievements on maize in Ethiopia: a review

Recent research into assessing and combatting maize weeds was reviewed based on scientific and working reports from the year 2011 onwards in Ethiopia. This review paper covered two main topics: assessment of major weed types and their impacts, and research results of weed management in the maize cropping system of the country. More than 80 major weed floras dominated by broad leaved weeds were found infesting maize fields in different localities. By competing, toxifying and/or parasitizing maize plants, they reduce the crop germination, growth and productivity. Several experiments indicated that maize yield loss due to uncontrolled weed growth varied from 35 to 87.5%, indicating that weed management is a critical factor for maize production in the country. Hoeing, hand weeding and pre-emergence herbicides application have been the most frequently used weed control practices to minimize the competition effect of weeds. So far, there has been no effective and sustainable individual weed control method for maize fields. Thus, future research should focus on developing integrated weed management that effectively reduce weed infestation and associated impacts, and improve productivity of the crop considering socio-economic condition of a specific maize producing agro-ecology of the country.

A global perspective of education in weed science

AbstractIn modern agriculture, weed problems are predicted to worsen and become more complicated as a result of increasing invasiveness, herbicide resistance, and emphasis on high-input methods. Weeds cause huge economic yield losses that range from US$100 million to US$26 billion globally. The knowledge of weed science has offered success in the past through effective, reasonably priced, and secure technologies; specifically, synthetic herbicides to effectively control weeds in agroecosystems. Weed science is accepted and adopted by many universities with teaching, research, and/or extension programs in agriculture. Globally, approximately 7% of all the universities offering agricultural education have dedicated weed science departments focusing on weed biology, ecology, and management. Some universities also offer weed science degree programs or at least certain courses in their degrees related to associated disciplines, such as plant protection, agronomy, and ecology. Although substantial advances have been made in weed science, such as a separate weed science discipline, specialized journals, and specific weed science societies and conferences worldwide, many constraints (e.g., lack of trained weed scientists) and barriers to adoption of new weed science technologies remain. Slow modernization in weed science research and low funding has slowed the progress of this discipline. New curricula in the weed science discipline should focus on the role of biochemistry, evolutionary biology, molecular biology, and genetics in weed science research.

Weed science research achievements on maize in Ethiopia: a review

Recent research into assessing and combatting maize weeds was reviewed based on scientific and working reports from the year 2011 onwards in Ethiopia. This review paper covered two main topics: assessment of major weed types and their impacts, and research results of weed management in the maize cropping system of the country. More than 80 major weed floras dominated by broad leaved weeds were found infesting maize fields in different localities. By competing, toxifying and/or parasitizing maize plants, they reduce the crop germination, growth and productivity. Several experiments indicated that maize yield loss due to uncontrolled weed growth varied from 35 to 87.5%, indicating that weed management is a critical factor for maize production in the country. Hoeing, hand weeding and pre-emergence herbicides application have been the most frequently used weed control practices to minimize the competition effect of weeds. So far, there has been no effective and sustainable individual weed control method for maize fields. Thus, future research should focus on developing integrated weed management that effectively reduce weed infestation and associated impacts, and improve productivity of the crop considering socio-economic condition of a specific maize producing agro-ecology of the country.

Weed science research achievements on maize in Ethiopia: a review

Recent research into assessing and combatting maize weeds was reviewed based on scientific and working reports from the year 2011 onwards in Ethiopia. This review paper covered two main topics: assessment of major weed types and their impacts, and research results of weed management in the maize cropping system of the country. More than 80 major weed floras dominated by broad leaved weeds were found infesting maize fields in different localities. By competing, toxifying and/or parasitizing maize plants, they reduce the crop germination, growth and productivity. Several experiments indicated that maize yield loss due to uncontrolled weed growth varied from 35 to 87.5%, indicating that weed management is a critical factor for maize production in the country. Hoeing, hand weeding and pre-emergence herbicides application have been the most frequently used weed control practices to minimize the competition effect of weeds. So far, there has been no effective and sustainable individual weed control method for maize fields. Thus, future research should focus on developing integrated weed management that effectively reduce weed infestation and associated impacts, and improve productivity of the crop considering socio-economic condition of a specific maize producing agro-ecology of the country.

Weed science research achievements on maize in Ethiopia: a review

Recent research into assessing and combatting maize weeds was reviewed based on scientific and working reports from the year 2011 onwards in Ethiopia. This review paper covered two main topics: assessment of major weed types and their impacts, and research results of weed management in the maize cropping system of the country. More than 80 major weed floras dominated by broad leaved weeds were found infesting maize fields in different localities. By competing, toxifying and/or parasitizing maize plants, they reduce the crop germination, growth and productivity. Several experiments indicated that maize yield loss due to uncontrolled weed growth varied from 35 to 87.5%, indicating that weed management is a critical factor for maize production in the country. Hoeing, hand weeding and pre-emergence herbicides application have been the most frequently used weed control practices to minimize the competition effect of weeds. So far, there has been no effective and sustainable individual weed control method for maize fields. Thus, future research should focus on developing integrated weed management that effectively reduce weed infestation and associated impacts, and improve productivity of the crop considering socio-economic condition of a specific maize producing agro-ecology of the country.

Agricultural Research Service Weed Science Research: Past, Present, and Future

AbstractThe U.S. Department of Agriculture–Agricultural Research Service (USDA-ARS) has been a leader in weed science research covering topics ranging from the development and use of integrated weed management (IWM) tactics to basic mechanistic studies, including biotic resistance of desirable plant communities and herbicide resistance. ARS weed scientists have worked in agricultural and natural ecosystems, including agronomic and horticultural crops, pastures, forests, wild lands, aquatic habitats, wetlands, and riparian areas. Through strong partnerships with academia, state agencies, private industry, and numerous federal programs, ARS weed scientists have made contributions to discoveries in the newest fields of robotics and genetics, as well as the traditional and fundamental subjects of weed–crop competition and physiology and integration of weed control tactics and practices. Weed science at ARS is often overshadowed by other research topics; thus, few are aware of the long history of ARS weed science and its important contributions. This review is the result of a symposium held at the Weed Science Society of America’s 62nd Annual Meeting in 2022 that included 10 separate presentations in a virtual Weed Science Webinar Series. The overarching themes of management tactics (IWM, biological control, and automation), basic mechanisms (competition, invasive plant genetics, and herbicide resistance), and ecosystem impacts (invasive plant spread, climate change, conservation, and restoration) represent core ARS weed science research that is dynamic and efficacious and has been a significant component of the agency’s national and international efforts. This review highlights current studies and future directions that exemplify the science and collaborative relationships both within and outside ARS. Given the constraints of weeds and invasive plants on all aspects of food, feed, and fiber systems, there is an acknowledged need to face new challenges, including agriculture and natural resources sustainability, economic resilience and reliability, and societal health and well-being.

A survey of weed research priorities: key findings and future directions

AbstractWe conducted an online survey of weed scientists in the United States and Canada to (1) identify research topics perceived to be important for advancing weed science in the next 5 to 10 years and (2) gain insight into potential gaps in current expertise and funding sources needed to address those priorities. Respondents were asked to prioritize nine broad research areas, as well as 5 to 10 subcategories within each of the broad areas. We received 475 responses, with the majority affiliated with academic institutions (55%) and working in cash crop (agronomic or horticultural) study systems (69%). Results from this survey provide valuable discussion points for policy makers, funding agencies, and academic institutions when allocating resources for weed science research. Notably, our survey reveals a strong prioritization of Cultural and Preventative Weed Management (CPWM) as well as the emerging area of Precision Weed Management and Robotics (PWMR). Although Herbicides remain a high-priority research area, continuing challenges necessitating integrated, nonchemical tactics (e.g., herbicide resistance) and emerging opportunities (e.g., robotics) are reflected in our survey results. Despite previous calls for greater understanding and application of weed biology and ecology in weed research, as well as recent calls for greater integration of social science perspectives to address weed management challenges, these areas were ranked considerably lower than those focused more directly on weed management. Our survey also identified a potential mismatch between research priorities and expertise in several areas, including CPWM, PWMR, and Weed Genomics, suggesting that these topics should be prime targets for expanded training and collaboration. Finally, our survey suggests an increasing reliance on private sector funding for research, raising concerns about our discipline’s capacity to address important research priority areas that lack clear private sector incentives for investment.

Potential wheat yield loss due to weeds in the United States and Canada

AbstractYield losses due to weeds are a major threat to wheat production and economic well-being of farmers in the United States and Canada. The objective of this Weed Science Society of America (WSSA) Weed Loss Committee report is to provide estimates of wheat yield and economic losses due to weeds. Weed scientists provided both weedy (best management practices but no weed control practices) and weed-free (best management practices providing >90% weed control) average yield from replicated research trials in both winter and spring wheat from 2007 to 2017. Winter wheat yield loss estimates ranged from 2.9% to 34.4%, with a weighted average (by production) of 25.6% for the United States, 2.9% for Canada, and 23.4% combined. Based on these yield loss estimates and total production, the potential winter wheat loss due to weeds is 10.5, 0.09, and 10.5 billion kg with a potential loss in value of US$2.19, US$0.19, and US$2.19 billion for the United States, Canada, and combined, respectively. Spring wheat yield loss estimates ranged from 7.9% to 47.0%, with a weighted average (by production) of 33.2% for the United States, 8.0% for Canada, and 19.5% combined. Based on this yield loss estimate and total production, the potential spring wheat loss is 4.8, 1.6, and 6.6 billion kg with a potential loss in value of US$1.14, US$0.37, and US$1.39 billion for the United States, Canada, and combined, respectively. Yield loss in this analysis is greater than some previous estimates, likely indicating an increasing threat from weeds. Climate is affecting yield loss in winter wheat in the Pacific Northwest, with percent yield loss being highest in wheat-fallow systems that receive less than 30 cm of annual precipitation. Continued investment in weed science research for wheat is critical for continued yield protection.

Integrated Weed Management Strategies for Sustainable Rice Production in Bangladesh

Weed causes huge reduction in crops yield, increases cost of cultivation, reduces input efficiency, interferes with agricultural operations, impairs quality, act as alternate hosts for several insect and diseases .Yield loss due to improper weeding at farmer’s field ranged from 4 to 22% depending on different rice ecosystem in Bangladesh. But at present considering all the cultivable land across the country and other issues; yield loss due to weeds considered about 2% in a consultation meeting.The present weed control practices in Bangladesh are characterized by intensive use of manual labour, use of herbicide and certain mechanical weeding. Manual weeding, besides laborious is inefficient as it is not done in time in most of the cases and always not practical because of various adverse conditions. Cost effective and integrated weed management system should be adopted to increase economic gain and sustainable rice production. Adopting timely and effectively appropriate weed management techniques we can reduce a significant amount of yield loss and about 0.43 million ton (MT) additional yield could be increased by 2030. To achieve the target weed management should be done from the very beginning of rice production and up to 30-35 DAP (days after planting) for Aus season, 35-40 DAT (days after transplanting) for T. Aman season and 40-45 DAT for Boro season which indicates critical period of weed infestation in Aus, T. Aman and Boro season. The main approach is that rice field have to keep free from weed up to that days by 2/3 hand weeding (HW) or application of herbicide fb (Followed by) 1HW or applying weeder fb 1HW which is called integrated weed management. Herbicide should be applied at proper time and dose which reduce 61% weeding cost. Mechanical weeding (MW) reduces 50% weeding cost that keeps environment friendly. Future weed science research specially herbicide efficacy with correct time and dose, new molecule herbicide with low environmental effect, herbicide residues in soil plant system, bioherbicide, allelopathic variety, weed competetive variety, mechanical weeder with related technological developments need a multidimensional approach for ecologically sustainable integrated weed management. Such a system will work toward a socially permissible, environmentally sound, economically feasible, productive and sustainable agricultural system. Bangladesh Rice J. 24 (2): 133-159, 2021

Buffelgrass invasion and glyphosate effects on desert soil microbiome communities

Buffelgrass (Cenchus ciliaris) is a drought-tolerant invasive grass in the Americas and Australia that significantly impacts native plant communities and ecosystems. Despite the clear need to develop a comprehensive understanding of how buffelgrass is able to invade and rapidly establish in arid ecosystems, there is still a lack of knowledge as to if and how this weed might change the soil microbiome in a way that affects its dominance in the presence of management. We investigated the effect of buffelgrass on soil microbial communities in areas that have either been exposed to or not exposed to glyphosate in Saguaro National Park, Arizona USA. We found that buffelgrass roots in invaded areas are surrounded by a distinct soil community that includes a greater number of nitrifiers than in uninvaded soil. We also observed increases in arbuscular mycorrhizal fungi, ectomycorrhizal fungi and methanotrophs with buffelgrass invasion compared to uninvaded soil. Finally, we found no evidence of glyphosate effects on the soil microbiome. Overall, our study results suggest that buffelgrass can escape the limitation of nutrient availability in arid ecosystems by directly or indirectly modifying the soil microbiome. The competitive dominance of buffelgrass in arid systems might be indirectly enhanced by nitrifiers and fungal symbionts, which are often involved in rapid biomass accumulation. This work highlights the importance of soil microbiome considerations in weed science research.

Weedy Conversation: What Weeds Are Saying to Your Crops May Make Them ‘Scream’ on the Inside

Decades of weed science research have pieced together how weeds communicate with crops and can have permanent and non‐reversible effects that result in rapid yield loss when the weeds emerge with the crops. This work has provided valuable information to CCAs to make recommendations to farmers and attracted attention to the ultimate goal of breeding crop plants less susceptible to this kind of damage. Earn 0.5 CEUs in Integrated Pest Management by reading this article and taking the quiz at https://www.certifiedcropadviser.org/education/classroom/classes/691.

Potential yield loss in grain sorghum (Sorghum bicolor) with weed interference in the United States

AbstractPotential yield losses in grain sorghum due to weed interference based on quantitative data from the major grain sorghum-growing areas of the United States are reported by the WSSA Weed Loss Committee. Weed scientists and extension specialists who researched weed control in grain sorghum provided data on grain sorghum yield loss due to weed interference in their region. Data were requested from up to 10 individual experiments per calendar year over 10 yr between 2007 and 2016. Based on the summarized information, farmers in Arkansas, Kansas, Missouri, Nebraska, South Dakota, and Texas would potentially lose an average of 37%, 38%, 30%, 56%, 61%, and 60% of their grain sorghum yield with no weed control, and have a corresponding annual monetary loss of US $19 million, 302 million, 7 million, 32 million, 25 million, and 314 million, respectively. The overall average yield loss due to weed interference was estimated to be 47% for this grain sorghum-growing region. Thus, US farmers would lose approximately 5,700 million kg of grain sorghum valued at approximately US $953 million annually if weeds are not controlled. With each dollar invested in weed management (based on estimated weed control cost of US $100 ha−1), there would be a return of US $3.80, highlighting the return on investment in weed management and the importance of continued weed science research for sustaining high grain sorghum yield and profitability in the United States.

Effects of seed bed types and weed control methods on the vegetative parameters of long cayenne pepper (Capsicum frutesens L)

Effects of seed bed types and weed control methods on the vegetative parameters of long cayenne pepper (Capsicum frutesens L)

Analysis of interval-grouped data in weed science: The binnednp Rcpp package.

Weed scientists are usually interested in the study of the distribution and density functions of the random variable that relates weed emergence with environmental indices like the hydrothermal time (HTT). However, in many situations, experimental data are presented in a grouped way and, therefore, the standard nonparametric kernel estimators cannot be computed.Kernel estimators for the density and distribution functions for interval‐grouped data, as well as bootstrap confidence bands for these functions, have been proposed and implemented in the binnednp package. Analysis with different treatments can also be performed using a bootstrap approach and a Cramér‐von Mises type distance. Several bandwidth selection procedures were also implemented. This package also allows to estimate different emergence indices that measure the shape of the data distribution. The values of these indices are useful for the selection of the soil depth at which HTT should be measured which, in turn, would maximize the predictive power of the proposed methods.This paper presents the functions of the package and provides an example using an emergence data set of Avena sterilis (wild oat).The binnednp package provides investigators with a unique set of tools allowing the weed science research community to analyze interval‐grouped data.

Development of a goosegrass (Eleusine indica) draft genome and application to weed science research.

Genomes are vital to the study of genomics, population genetics, and evolution of species. To date, only one genome (Echinochloa crus-galli) for C4 annual weedy grass species has been sequenced. Research was conducted to develop a draft genome of goosegrass (Eleusine indica; 2n = 2x = 18), one of the most common and troublesome weeds in the world. A draft assembly of an approximately 492 Mb whole-genome sequence of goosegrass was obtained by de novo assembly of paired-end and mate-paired reads generated by Illumina sequencing of total genomic DNA. The genome was assembled into 24,072 scaffolds with N50 = 233,459 bp. More than 99% of transcriptome sequences were mapped to the goosegrass draft genome, and 95% of the commonly conserved plant genes were present. The assembled genome contains 25,467 unique protein-coding genes. Genes associated with herbicide resistance were obtained and variant calling allowed the detection of 754,409 single nucleotide polymorphisms. In addition, we also report 115,417 simple sequence repeats which can be deployed in population genetics and phylogenetic analysis. This is the first report of genome sequence of goosegrass. Our assembly was able to identify all major herbicide-resistance related genes and develop a useful tool for other genomic and evolutionary analysis. © 2019 Society of Chemical Industry.

Potential yield loss in sugar beet due to weed interference in the United States and Canada

AbstractThe objective of this WSSA Weed Loss Committee report is to provide quantitative data on the potential yield loss in sugar beet due to weed interference from the major sugar beet growing areas of the United States and Canada. Researchers and extension specialists who conducted research on weed control in sugar beet in the United States and Canada provided quantitative data on sugar beet yield loss due to weed interference in their regions. Specifically, data were requested from weed control studies in sugar beet from up to 10 individual studies per calendar year over a 15-yr period between 2002 and 2017. Data collected indicated that if weeds are left uncontrolled under optimal agronomic practices, growers in Idaho, Michigan, Minnesota, Montana, Nebraska, North Dakota, Ontario, Oregon, and Wyoming would potentially lose an average of 79%, 61%, 66%, 68%, 63%, 75%, 83%, 78%, and 77% of the sugar beet yield. The corresponding monetary loss would be approximately US$234, US$122, US$369, US$43, US$40, US$211, US$12, US$14, and US$32 million, respectively. The average yield loss due to weed interference for the primary sugar beet growing areas of North America was estimated to be 70%. Thus, if weeds are not controlled, growers in the United States would lose approximately 22.4 million tonnes of sugar beet yield valued at approximately US$1.25 billion, and growers in Canada would lose approximately 0.5 million tonnes of sugar beet yield valued at approximately US$25 million. The high return on investment in weed management highlights the importance of continued weed science research for sustaining high crop yield and profitability of sugar beet production in North America.

Dan Watkins Scholarship in Weed Science

Dan Watkins was one of the founders of the Ivon Watkins Ltd herbicide company, based in New Plymouth, which later became Ivon Watkins Dow and is now Dow AgroSciences. He was a leading figure in the early weed science research arena within New Zealand. Dan Watkins was a founder of the New Zealand Weeds conference, forerunner of the New Zealand Plant Protection Society. He was also a member of the New Zealand National Research Council and was involved with other scientific bodies. This scholarship has been set up and financed by Dr
 George Mason, one of the founders of Taranaki Nuchem (now Zelam Limited), in memory of Dan Watkins and to recognise his contribution to weed science within New Zealand.
 David Kerr, recipient of the 2017/18 Dan Watkins Scholarship in Weed Science, is an MSc student at Canterbury University. His thesis is on the reproduction and ecology of Mimulus guttatus DC, a persistent riparian weed imported from the western United States into New Zealand as an ornamental plant. This weed grows vigorously from the smallest fragments and has potential to cause major damage to river systems; crowding out natives and increasing flooding potential. David’s research aims to investigate how reproductive strategy facilitates the spread of M. guttatus, particularly the role of seed banks in establishing populations after habitat disturbance.
 Mimulus guttatus produces abundant seeds of very small size (approx. 500 µm in diameter), which have been demonstrated to be viable after travelling hundreds of metres downstream or dispersing in large numbers by wind from dry seed pods. Traditional management techniques involve mechanical clearance or use of herbicides in affected rivers adjoining pasture land. These approaches have notable negative consequences, including waterway contamination and facilitation of fragment dispersal and growth.
 The first part of David’s thesis involved a survey of 250 contiguous 50-m long stretches of river at six valley locations around Banks Peninsula; recording the presence of M. guttatus and abundance as well as site data such as shading and evidence of grazing on M. guttatus plants. The data from this survey indicated a trend towards greater abundance in more open areas and occasional patches in more shaded regions where the canopy allows sufficient light to grow. Previous work has identified a lack of understanding of transient overwintering seed banks.
 The second part of David’s thesis will investigate the hypothesis that persistent seed banks allow M. guttatus to establish upstream of populations in shaded areas when the canopy is disturbed. Mimulus guttatus in its native range has high fitness costs associated with selfing. The third will investigate the reproductive strategy of M. guttatus with reference to rates of selfing, and seed viability to test the hypothesis that historic pollinator and mate limitation have driven a change towards selfing.
 This work will further the understanding of the reproductive strategy of M. guttatus and how it invades river systems and inform land-management and conservation decisions. This has particular relevance to the role of sustainable ecosystem-level approaches to weed management such as native shade belts and conservation of existing forest around waterways to prevent weed establishment.

Weed research status, challenges, and opportunities in China

Weeds are a major constraint to crop production, which is of crucial importance for food security in China given its 1.37 billion population. In recent years, an increasing number of herbicide resistant weeds and invasive alien plants have become prevalent and challenging to manage in China as elsewhere in the world. In this review, we provide an overview of several key facets of weed science research in China, including (i) weed community shifts as a result of cropping system and weed management changes, (ii) the status of invasive weeds, (iii) weed management options for the increasing number of herbicide resistant weeds, and (iv) the challenges and opportunities in weed research in China. Invasive weeds in tandem with changes in cropping systems have significantly altered weed communities in crops such as rice (Oryza sativa L.), wheat (Triticum aestivum L.), maize (Zea mays L.), soybean [Glycine max (L.) Merr.], cotton (Gossypium hirsutum L.), and oilseed rape (Brassica napus L.). At present, 30 weed species have evolved resistance to 11 herbicide sites of action that includes 48 commonly used herbicides. Although tactics such as crop rotation and biological control have been used to manage some weeds in China, weed control has and continues to rely primarily on herbicides. Research priorities for weed management include developing and implementing a preventive risk assessment framework and a better understanding of the mechanisms that allow some alien weeds to be highly aggressive and difficult to manage. Moreover, the development and evaluation of additional weed management tactics such as breeding competitive crop cultivars, straw mulching, optimizing water management, and site-specific fertilizer and herbicide applications warrant further study. The use of an integrated weed management approach in coming years will rely heavily on a more in-depth understanding of the biological and ecological principles governing weed population dynamics. Approaches such as herbicide resistance weed management (HRWM) programs in tandem with conservation agriculture (CA) can be employed to develop sustainable weed management strategies in cropping systems.