Weed Ecology Research Articles

Improved Forage Production in Ethiopia: Utilization, Challenges and Prospects for Adoption: A Review

There are several factors that hinder the productivity of livestock in Ethiopia of which nutrition contributes the largest share. The quality and quantity of feed are poor challenging livestock production. Nowadays, due to the rapid increase of human population and increasing demand for food, grazing lands are steadily declining by being shifted to arable lands for crop production. As a result, food crop residues are providing a considerable quantity of dry season feed in most farming areas of the country. However, the feeding value of crop residues is very poor. One way to alleviate this problem is supplementation of crop residue through the use of improved forage and fodder trees. Research and development agents have been testing and identifying promising forages that are suitable for pasture rehabilitation in a wide range of agro-ecological zones besides animal feeding. The use of forage legumes have a paramount role resulted in increasing soil nitrogen available for food crops because of their ability to fix nitrogen. Moreover, multipurpose browse trees and shrubs serve as fuel wood resource. Improved forage legumes and browse species provides protein which enhances the feed resources available for livestock. The major impediments of improved forages production in different parts of the country are ecological deterioration, overgrazing, land tenure, border conflict, drought, weed and bush encroachment, lack of seed and planting materials. The diverse topography coupled with environmental heterogeneity offers favorable environments for pasture species, herbaceous legumes and browse trees/shrubs. Hence, assessing the conditions, challenges, opportunities and recommendations of improved forage production is very imperative for effective and efficient utilization of these feed resources to boost the productivity of the livestock sector in the country. Keywords: improved forages, nutrition, crop residues, challenges, utilization DOI : 10.7176/JBAH/9-21-02 Publication date: November 30 th 2019

Ecological weed control in rice and maize using Orbygnia phalerata with focus on the weed seedbank in the soil

The aim of this study was to evaluate the effect of mulching with dry leaves of babassu palm (Orbygnia phalerata Mart.) on germination of weed seed bank on rice tiller number and on grain yield of rice and maize in Maranhão state, northeastern Brazil. In the field the experimental design was a split plot in a randomized complete block with 15 replications. Rice, maize and rice intercropped with maize were allocated to the main plots and mulching treatments with unprocessed whole dried palm leaves (0 and 23 t ha-1) to the subplots. Germination of the weed seed bank was assessed after crop harvest in the greenhouse by means of a collection of three soil samples per subplot (n = 270) with an open metal device of 25 cm in length x 16 cm in width x 3 cm in height as sampling unit. Soil samples were placed in aluminum trays in the greenhouse and irrigated daily. The germinated weed species were identified and counted every fifteen days. The results showed that mulching can reduce germination in the weed seed bank up to 55% and promoted a significant increase in rice tiller number from 63 to 95 m-2, grain yield of rice from 1,077 to 2,251 kg ha-1 and grain yield of maize from 1,137 to 2,293 kg ha-1. Therefore, mulching can be recommended for weed control in smallholder farming of rice and maize crops.

Potential for organic conversion and energy efficiency of conventional livestock production in a humid tropical region of Mexico

Abstract Organic livestock production uses low levels of external inputs and less fossil fuel than does conventional livestock production, and therefore it is more energy efficient, reduces contamination, provides healthy food and ecosystem services, and contributes to reducing and adapting to climate change. This article characterizes livestock production and evaluates the potential and limitations of organic conversion and the energy efficiency of conventional dual purpose (milk and meat) cattle production in a humid tropical region of Chiapas, Mexico. Our analysis indicates that for the Livestock Production Units (LPU) of the study region, the greater the organic livestock conversion index (OLCI, 0–100%), the lower the values for herd size, stocking rate, total feed supplement, annual cost of feed purchased for cattle, and production cost per cow; by contrast, those LPU with greater OLCI have greater economic efficiency. Furthermore, the greater the OLCI, the greater the values of the following indicators: Feeding management, Sustainable grassland management, Ecological weed control in grasses and crops, Veterinary prevention and care, Food safety, and Ecological farm management. A direct relationship exists between the potential for organic conversion (>OLCI) and energy and economic efficiency. Meanwhile, an inverse relationship was found between OLCI and energy efficiency on the one hand, and - on the other - use of direct and indirect energy, total energy input, energy output, and number of people that could be fed with the energy from milk and meat produced. Converting LPU to organic production and increasing their energy efficiency depends on farmers further developing their abilities to manage sustainable agricultural systems through advisory, technical assistance, and permanent financial support.

On the Ecology of Weeds in the Orchards habitat During Summer Season in Nile Delta, Egypt

On the Ecology of Weeds in the Orchards habitat During Summer Season in Nile Delta, Egypt

On the Ecology of Weeds in the Orchards habitat During Summer Season in Nile Delta, Egypt

The present study aims to investigate the ecology of weed communities associated with some orchards habitat using the variations in environmental factors to determine the distribution and abundance of the recognized weed communities in the study areas. The sampled stands were distributed in four Governorates. Field visits were started from January 2014 to September 2015, 45 stands were selected for sampling the vegetation types during summer season. The application of TWINSPAN classification based on the importance values of 49 plant species recorded in selected 45 sampled stands representing the summer orchards sites in the study areas led to the recognition of four vegetation groups (Euphorbia heterophylla, Commelina benghalensis, Cynanchum acutum and Xanthium strumarium were the dominate plants). In summer season, the application of DCA technique proved that, the plant communities recognized by TWINSPAN classification were markedly distinguishable and having clear pattern of segregation on the ordination plane. The application of CCA technique was used to determine the most effective soil variables controlling the abundance and distribution of weed communities associated during summer season.

Shifting the Paradigm: An Ecological Systems Approach to Weed Management

Weeds have been historically, and are still today, the primary and most economically important pest in agriculture. Several selection pressures associated with weed management, such as an overreliance on herbicides, have promoted the rapid evolution of herbicide-resistant weeds. Integrated Weed Management (IWM) is promoted as an ecological systems approach, through the combination of biological, chemical, cultural, ecological, and mechanical control methods. The concept of a systems approach is defined as managing weeds by combining practice and knowledge with the goals of increasing yield and minimizing economic loss, minimizing risks to human health and the environment, and reducing energy requirements and off-target impacts. The reliance on herbicides in modern cropping systems has shifted the management focus from requiring intimate knowledge of biology, ecology, and ecological systems to herbicide chemistry, mixes, and rotations, application technology, and herbicide-tolerant crop traits. Here, an ecological systems approach is considered, examining new trends and technologies in relation to IWM and weed ecology. Prevention of spread, seedbank management, crop rotations, tillage, cover crops, competitive cultivars, biological weed control, and future solutions in concept-only are presented, and knowledge gaps are identified where research advancements may be possible. An ecological systems approach will provide improved stewardship of new herbicide technologies and reduce herbicide resistance evolution through diversification of selection pressures. Agroecological interactions should be studied in light of new, developing weed control technologies. The science of weed management needs to refocus on the foundations of weed biology and ecology to enable an ecological systems approach and promote agricultural sustainability.

Understanding the nexus of rising CO2, climate change, and evolution in weed biology

AbstractRapid increases in herbicide resistance have highlighted the ability of weeds to undergo genetic change within a short period of time. That change, in turn, has resulted in an increasing emphasis in weed science on the evolutionary ecology and potential adaptation of weeds to herbicide selection. Here we argue that a similar emphasis would also be invaluable for understanding another challenge that will profoundly alter weed biology: the rapid rise in atmospheric carbon dioxide (CO2) and the associated changes in climate. Our review of the literature suggests that elevated CO2 and climate change will impose strong selection pressures on weeds and that weeds will often have the capacity to respond with rapid adaptive evolution. Based on current data, climate change and rising CO2 levels are likely to alter the evolution of agronomic and invasive weeds, with consequences for distribution, community composition, and herbicide efficacy. In addition, we identify four key areas that represent clear knowledge gaps in weed evolution: (1) differential herbicide resistance in response to a rapidly changing CO2/climate confluence; (2) shifts in the efficacy of biological constraints (e.g., pathogens) and resultant selection shifts in affected weed species; (3) climate-induced phenological shifts in weed distribution, demography, and fitness relative to crop systems; and (4) understanding and characterization of epigenetics and the differential expression of phenotypic plasticity versus evolutionary adaptation. These consequences, in turn, should be of fundamental interest to the weed science community.

An online decision support tool to evaluate ecological weed management strategies

AbstractWeeds remain the most commonly cited concern of organic farmers. Without the benefit of synthetic herbicides, organic farmers must rely on a host of ecological weed management (EWM) practices to control weeds. Despite EWM’s ability to improve soil quality, the perceived rate of integrated EWM strategy adoption remains low. This low adoption is likely a result of the complexity in designing and evaluating EWM strategies, the tendency for outreach to focus on the risks of EWM strategies rather than their benefits, and a lack of quantitative measures linking the performance of EWM strategies to farmers’ on-farm objectives and practices. Here we report on the development and deployment of an easy-to-use online decision support tool (DST) that aids organic farmers in identifying their on-farm objectives, characterizing the performance of their practices, and evaluating EWM strategies recommended by an expert advisory panel. Informed by the principles of structured decision making, the DST uses multiple choice tasks to help farmers evaluate the short- and long-term trade-offs of EWM strategies, while also focusing their attention on their most important objectives. We then invited organic farmers across the United States, in particular those whose email addresses were registered on the USDA’s Organic Research Integrity Database, to engage the DST online. Results show considerable movement in participants’ (n = 45) preferences from practices focused on reducing weeding costs and labor in the short term to EWM strategies focused on improving soil quality in the long term. Indeed, nearly half of those farmers (48%) who initially ranked a strategy composed of their current practices highest ultimately preferred a better-performing EWM strategy focused on eliminating the weed seedbank over 5 yr.

Researches on ecological weed control in vegetable crops

In recent years, intense concerns about the increasing resistance of weed populations to herbicide treatments, the low availability of bioactive ingredients for vegetable crops, as well as the expansion of organic farms for these niche crops have stimulated the development of new non-chemical methods of control or new approaches to those already used. In general, vegetable crops exhibit increased sensitivity to weeds compared to other crops. Therefore, weed control in organic vegetable crops is a real challenge for farmers, mainly using the so-called physical combat methods. Therefore, weed destruction is accomplished by using manual, mechanical, thermal or mulching means. The paper presents the preliminary experimental results obtained under laboratory conditions, referring to an innovative model of equipment for the ecological weed control in vegetable crops. It will achieve the destruction of weeds, combining the thermal method based on using hot water with the mechanical one, by equipping the machine withenvironmentally friendlyactive parts. The results obtained constitute an important premise for developing efficient equipment for the ecological weed control that can be used within integrated control systems, specific for organic onion, bean and bell pepper crops.

Integrated weed management for sustainable agriculture

Eminent weed scientist Robert Zimdahl has attracted prominent weed ecology experts from Canada, France, Australia, Israel, and U.S., primarily from universities and national research groups, to pre...

Study the Use of Compost Tea in Weed Suppression

Applying compost tea, prepared by aeration, without or with water hyacinths by either water or solvent extraction, showed phytotoxic in practice of suppress weed. Compost tea extracts had influential inhibition based on its concentrations after 24 h brewing on Zea mays and P. oleracea seed germination and seedling growth. Water based (CW2) and solvent based (CS2) extracted by diethyl ether:ethyl acetate (1:1) after 48 h of brewing could be highly phytotoxic compared to other types of compost tea. Water-based extract (WW3) compost tea mixed with dried water hyacinth (DWH) after 72 h brewing and the solvent based WS2 (CT mixed with DWH) at both 300 and 500 µg ml−1 after 48 h brewing had the strongest inhibition effects and completely inhibited Z. mays and P. oleracea germination. High levels of toxicity observed from the solvent-based extract was WS2 after 48 h of brewing, which gave the least EC50 values in Z. mays and P. oleracea, reached (175.0 and 160.0) root length (180.0 and 195.0) germination and (200 and 190) µg ml−1 shoot length, respectively. Water-based CW2 and CW3 extracted with ethyl acetate and solvent-based CS2 and CS3 (diethyl ether:ethyl acetate) after brewing 48 and 72 h, respectively, revealed to LC–MS/MS analysis, the profiles have shown acetic acid, propionic acid, methyl butyric acid, cinnamic acid, coumaric acid, caffeic acid, ferulic acid, gallic acid, syringic acid, 5-hydroxyferulic acid and sinapic acid. There are substantial differences in these substance phytotoxicity, that differences could be attributed to the phytotoxicity of compost tea according to brewing time and concentrations, the case that could pave the way towards using it in bioreactors to produce natural herbicidal bioactive constituents for use in ecological weed management. Our aim was to perform bioassays for the phytotoxicity of compost tea and to identify its chemicals.

Using ecology and technology to Control Weeds

Using ecology and technology to Control Weeds

An ecological perspective on managing weeds during the great selection for herbicide resistance.

More than 70 years after modern agriculture declared a 'war on weeds', they continue to thrive and suppress crop yields. Viewing weeds as an enemy that can be defeated if only a powerful enough technology can be deployed is a losing proposition. The latest evidence for the inadequacy of this approach, rampant evolution of multiple herbicide-resistant weed genotypes and dwindling options for chemical control in many production systems, should be seen as an urgent message to all those concerned with the science and practice of weed management: we need another way of thinking about the weed resistance issue. Fortunately, the theoretical and practical foundation of this alternative approach, ecological weed management, has been in development for decades. Here, we use Barry Commoner's laws of ecology as a conceptual frame for a review of some of the fundamental concepts of ecological weed management. © 2018 Society of Chemical Industry.

Carlos L. Ballaré.

Carlos L. Ballaré.

Using stable isotopes and functional weed ecology to explore social differences in early urban contexts: The case of Lattara in mediterranean France

Integrated stable isotope investigation of plant and animal ecology can shed new light on the practicalities and politics of land management. Ecological analysis of archaeobotanical weed flora offers a complementary approach to arable growing conditions. Here we introduce the first combined study of stable isotope compositions (carbon and nitrogen) of plant and faunal remains and functional weed ecology from mediterranean France in order to investigate agricultural strategies under urbanisation and their social implications. Animal bones and charred crops and weeds are investigated from two archaeologically distinct residential areas from 5th century BCE Lattara, zones 1 and 27, during a period characterised by significant urban expansion in the region. Plant carbon and nitrogen isotope composition and functional weed ecology suggest some differences in growing conditions between crops found in the two zones, zone 27 being associated with more intensively cultivated crops than zone 1, where extensive cultivation, which can achieve much greater surplus, was dominant. These findings coincide with archaeological evidence of a ‘richer’ variety of material culture and foodstuffs in zone 1. Carbon and nitrogen isotopic values of animal bone collagen suggest that the main domesticates from both zones consumed a similar diet; however, rabbits exhibit a difference, with those from zone 1 having significantly higher δ15N, implying that the two zones sourced this species differently.

Reviewing research priorities in weed ecology, evolution and management: a horizon scan.

SummaryWeedy plants pose a major threat to food security, biodiversity, ecosystem services and consequently to human health and wellbeing. However, many currently used weed management approaches are increasingly unsustainable. To address this knowledge and practice gap, in June 2014, 35 weed and invasion ecologists, weed scientists, evolutionary biologists and social scientists convened a workshop to explore current and future perspectives and approaches in weed ecology and management. A horizon scanning exercise ranked a list of 124 pre‐submitted questions to identify a priority list of 30 questions. These questions are discussed under seven themed headings that represent areas for renewed and emerging focus for the disciplines of weed research and practice. The themed areas considered the need for transdisciplinarity, increased adoption of integrated weed management and agroecological approaches, better understanding of weed evolution, climate change, weed invasiveness and finally, disciplinary challenges for weed science. Almost all the challenges identified rested on the need for continued efforts to diversify and integrate agroecological, socio‐economic and technological approaches in weed management. These challenges are not newly conceived, though their continued prominence as research priorities highlights an ongoing intransigence that must be addressed through a more system‐oriented and transdisciplinary research agenda that seeks an embedded integration of public and private research approaches. This horizon scanning exercise thus set out the building blocks needed for future weed management research and practice; however, the challenge ahead is to identify effective ways in which sufficient research and implementation efforts can be directed towards these needs.

Potential allelopathic effects of rice plant aqueous extracts on germination and seedling growth of some rice field common weeds

Given the increasing emphasis on sustainable agriculture, and concerns about the adverse effects of extensive use of farm chemicals, research attention is now being focused on reducing the dependence upon synthetic herbicides, and finding alternative strategies for weed management. Allelopathic properties of crop plants may allow us to use lower amounts of herbicides with benefits for the environment and human health. Considering these aspects, the present study was conducted to investigate the allelopathic effects of six selected rice varieties (WITA-3, WITA-4, WITA-12, Woo-Co, Fukuhibiki and Kalizira) collected from Bangladesh Rice Research Institute (BRRI) on seed germination and seedling growth of five weed species; Echinochloa crus-galli, Cyperus difformis, Cyperus iria, Fimbristylis milliacea and weedy rice. The aqueous extracts of all the rice cultivars caused inhibitory effects on seed germination and seedling shoot-root length of all the weed species. However, the inhibitory effects of different rice varieties varied significantly based on the differences of weed species and weedy rice found to be the least affected compared to other weeds. WITA-12 resulted about 50% germination inhibition, 25% shoot length reduction and 23% root length reduction respectively compared to control. On the basis of average percentage inhibition, rice varieties ranked in order; WITA-12>WITA- 4>Fukuhibiki>Kalizira>Woo-Co>WITA-3. Our results suggested that there is a possibility of developing a new ecological weed management strategy using rice cultivars with higher allelopathic potentials. This means breeding of rice cultivars with higher allelopathic potential may provide natural and sustainable weed management options for rice growers.

In the weeds: distinguishing organic farmers who want information about ecological weed management from those who need it

AbstractThe benefits of farming organically in the USA are increasingly known; however, organic farmers also encounter considerable risks, especially from weeds. Without herbicides, organic farmers can rely only on crop rotations, mechanical cultivation, manual weeding, beneficial insects and other cultural practices, termed ecological weed management (EWM), to control weeds. Despite promising results and the many ways in which EWM can be employed, it remains poorly adopted by the organic community. Organic farmers resist research and recommendations from University scientists and Extension, instead preferring to rely on local family and friends and their own experience to guide decisions. Here we investigate factors that may lead organic farmers to recognize that they need additional information about EWM and to seek that information out. Using a national survey of organic farmers (n= 554) and a risk-information seeking and processing model, we show that farmers’ risk and benefit perceptions, worry, social norms encouraging seeking out information, and farmers’ own perceived knowledge gaps, particularly with respect to their most problematic weed, influence information-seeking behavior. Identifying characteristics that may distinguish those organic farmers who need and want additional information, we provide recommendations to Extension and University scientists about how best to communicate, build trust and provide decision support to the organic community with respect to EWM.

Allelopathic Effects of Three Sweet Potato Cultivars (Ipomoea batatas) on the Invasive Plant Mikania micrantha.

Sweet potato [Ipomoea batatas (L.) Lam] is an important locally grown cash crop in China; it was demonstrated to suppress the invasive plant Mikania micrantha (M. micrantha) H.B.K through strong competitiveness, but its allelopathic effects on this weed were unknown. The present study aimed to explore the allelopathic potential of sweet potato on M. micrantha. The allelopathic effects of water extracts and soil incorporation from leaves of three sweet potato cultivars (SP1, SP0 and SP9) on the sprout seedling growth of invasive plant M. micrantha in Yunnan Province, China, were studied under laboratory and greenhouse conditions. Stem length, root biomass, aboveground biomass and total biomass of M. micrantha were significantly reduced with increasing concentration in both leaf water extracts and leaf soil incorporation of three sweet potato cultivars. Among these, SP1 had the strongest inhibition and the next highest impact was from SP0 with the lowest effect from SP9. The highest inhibition rates were seen for root biomass, followed by total biomass, whereas the lowest impact was on aboveground biomass. The strong correspondence between results for both leaf water extracts and leaf soil incorporation provided a good demonstration that compounds produced by sweet potato have allelopathic effects on M. micrantha. The general inhibition of M. micrantha by sweet potato followed the order among the three sweet potato cultivars tested as SP1, SP0 and SP9. Moreover, the synthetical allelopathic indices of leaf soil incorporation of three cultivars on M. micrantha were generally higher than these of leaf water extracts. Competition and allelopathy have primarily been seen as separate ecological weed management tools, but as these have demonstrated in the case of sweet potato where both mechanisms inhibit weed growth, there is potential for synergism between competition and allelopathy in the reduction of weed infestations.

Biodiversity, distribution, ecology and management of non-native weeds in Mexico: a review

The current knowledge on the richness, ecology, distribution and management of non-native flowering weeds in Mexico and some data on their possible environmental and economic impact are briefly reviewed. We reviewed 216 refereed publications, most indexed international articles. Most publications refer to management sensu lato (34.9%), floristics (19.5%), ecology (21.5%), and detection of new non-native weeds (13.3%). The most complete research area is floristics, along with species inventories with their incidence at the state level. The publications, although interesting and of high quality, are disjointed and rarely coordinated with decision makers, general public or policy makers. It is estimated that there are about 700 wild non-native species in Mexico; 80% naturalized and we estimate that there are between 58 and 180 invasive weed species that cause environmental or socioeconomic damage. The 700 species represent 2.8% of the 23,000 species of Mexican flora. Although there is no overall estimate of the cost of the losses caused by weeds introduced for Mexico, it is argued that it is high in terms of agriculture, environment and human health. A number of measures are suggested to generate the scientific knowledge needed to prevent and/or sustainably manage invasive weed invasions.