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A meta-analysis of field bindweed (Convolvulus arvensis L.) and Canada thistle (Cirsium arvense L.) management in organic agricultural systems
Abstract
Organic farming has become a major agricultural and economic sector, and weed management is one of the primary challenges facing the industry. Of particular concern are rhizomatous perennial weeds such as field bindweed (Convolvulus arvensis L.) and Canada thistle [Cirsium arvense (L.) Scop.] which are highly competitive and not easily controlled in organic systems. We conducted meta-analyses of the existing literature to 1) identify promising management approaches for these weeds in the absence of synthetic herbicides and 2) determine which aspects of field bindweed and Canada thistle management warrant further study. Mechanical control (i.e. plowing, cultivation, hoeing) was the most studied management category in annual cropping systems, accounting for 40% of data extracted, but did not outperform most of the other management actions overall, possibly due to the variability in specific methodology (i.e. timing, frequency, depth, implement). In annual systems, integrated management, or the combination of two or more control methods, emerged as the management technique that caused the greatest decrease in abundance and survival for field bindweed. We identified several additional management techniques that decreased field bindweed and/or Canada thistle in both annual and perennial systems including biocontrol, mowing, grazing, crop diversification, solarization, shading, flaming, and crop competition. However, organic producers continue to struggle with these species. This discrepancy may originate from the fact that most of the studies we evaluated reported impacts over short time spans, with 53% being conducted for a period of one to two years, and only 9% conducted for five or more years. Further, only 16% of field bindweed and 26% of Canada thistle studies reported measures of variability. Longer-term research focused on sustainable perennial weed management systems is needed in addition to research about short-term interventions.
... Additionally, tillage can disperse vigorous C. arvense rhizomes, causing a rapid increase of the weed's population (Tiley, 2010). As a result, C. arvense has become a serious management problem within organic cropping systems, where alternative management tools need to be explored (Tautges et al., 2016;Orloff et al., 2018). ...
... Competitive crops can disrupt weed growth by reducing resource availability and niche dominance of weed species (Liebman and Dyck, 1993). However, the difficult nature of reducing C. arvense rhizomes, particularly in organic agriculture (Tautges et al., 2016;Orloff et al., 2018), has led to a search for alternative and integrated tactics, including biocontrol agents that inhibit root development (Berner et al., 2013;Cripps et al., 2014). The use of biocontrol agents can be challenging due to a lack of host specificity, varied responses to environmental conditions, and mismanagement. ...
... Sustainable C. arvense management in organic cropping systems is a primary challenge in temperate regions around the globe. Integrated weed management strategies are needed to reduce the abundance, slow the spread, and minimize the impact of C. arvense in cropping systems over a long term (Liebman et al., 2001;Liebman and Davis, 2009;Davis et al., 2018;Orloff et al., 2018). In this study, we found that the integration of P. punctiformis and crop competition interacted to impact C. arvense biomass and competitive ability. ...
Cirsium arvense (Canada thistle) is a perennial weed that causes significant economic losses in agriculture. An extensive rhizomatous root system makes C. arvense difficult to manage, particularly in agricultural systems that use tillage as a primary management tool. There is a need for the development of integrated weed management toolsets that include C. arvense biological controls. Puccinia punctiformis (thistle rust) is an autoecious fungal pathogen that systemically infects C. arvense, with the potential to reduce host vigor over time. The goal of this study was to integrate the P. punctiformis biocontrol with a simulated annual cropping sequence in a greenhouse environment and evaluate C. arvense's above-and belowground biomass production, and its competitive ability. Repeated P. punctiformis inoculations produced systemically infected C. arvense stems in greenhouse pots over time. Cirsium arvense that was inoculated with P. punctiformis had 1.6 grams/pot (p = 0.0019) less aboveground biomass and 5.6 grams/pot (p< 0.001) less belowground biomass, compared to the non-inoculated (control). Puccinia punctiformis and crop competition interacted additively to lower aboveground (p<0.001) and belowground (p<0.001) C. arvense biomass more than individual use of either the biocontrol or competition alone. The aboveground competition intensity of C. arvense in a mixed crop sequence, relative to non-inoculated C. arvense grown in a monoculture, was moderately impacted by the P. punctiformis biocontrol (p = 0.0987). These results indicate that systemic infection can reduce biomass production and the competitive ability of C. arvense. Overall, P. punctiformis can be integrated into competitive annual cropping sequences with the potential to reduce C. arvense vigor over time.
... In agreement with our first expectation and previous studies conducted in this region [10,12], more weed biomass, and increased species richness and diversity were observed in the tilled organic system compared with the no-till conventional cropping system. In agreement with our second expectations, it was also observed that there was an increased abundance in difficult-to-manage perennial weed species [44] in the grazed/reduced-till organic system, a shift that could hinder the adoption of integrated crop and livestock production tactics. In partial contradiction with our last expectation, weed community responses to temperature and moisture manipulations differed across variables: while biomass, species richness, and Simpson's diversity estimates did not differ across treatments, a significant, but minor shift, in weed community composition was observed as a function of temperature and climate manipulations. ...
... In agreement, an increase C. arvense and T. officinale abundance was observed in the grazed/reduced-till organic system compared with the tilled organic system. Perennial weed species are a particular management challenge in organic cropping systems [44,48], and the increase in C. arvense and T. officinale biomass observed in the grazed/reduced-till organic system indicates that grazing may not a reliable method as a unique control to deal with problematic weed species. While a meta-analysis revealed that integrated weed management practices appear to be the most promising approach to manage perennial weeds in organic cropping systems [44], our results highlight the inadequacy of integrating crop and livestock operations in organic systems to reduce tillage intensity while minimizing perennial weeds. ...
... Perennial weed species are a particular management challenge in organic cropping systems [44,48], and the increase in C. arvense and T. officinale biomass observed in the grazed/reduced-till organic system indicates that grazing may not a reliable method as a unique control to deal with problematic weed species. While a meta-analysis revealed that integrated weed management practices appear to be the most promising approach to manage perennial weeds in organic cropping systems [44], our results highlight the inadequacy of integrating crop and livestock operations in organic systems to reduce tillage intensity while minimizing perennial weeds. ...
Understanding the impact of biological and environmental stressors on cropping systems is essential to secure the long-term sustainability of agricultural production in the face of unprecedented climatic conditions. This study evaluated the effect of increased soil temperature and reduced moisture across three contrasting cropping systems: a no-till chemically managed system, a tilled organic system, and an organic system that used grazing to reduce tillage intensity. Results showed that while cropping system characteristics represent a major driver in structuring weed communities, the short-term impact of changes in temperature and moisture conditions appear to be more subtle. Weed community responses to temperature and moisture manipulations differed across variables: while biomass, species richness, and Simpson’s diversity estimates were not affected by temperature and moisture conditions, we observed a minor but significant shift in weed community composition. Higher weed biomass was recorded in the grazed/reduced-till organic system compared with the tilled-organic and no-till chemically managed systems. Weed communities in the two organic systems were more diverse than in the no-till conventional system, but an increased abundance in perennial species such as Cirsium arvense and Taraxacum officinale in the grazed/reduced-till organic system could hinder the adoption of integrated crop-livestock production tactics. Species composition of the no-till conventional weed communities showed low species richness and diversity, and was encompassed in the grazed/reduced-till organic communities. The weed communities of the no-till conventional and grazed/reduced-till organic systems were distinct from the tilled organic community, underscoring the effect that tillage has on the assembly of weed communities. Results highlight the importance of understanding the ecological mechanisms structuring weed communities, and integrating multiple tactics to reduce off-farm inputs while managing weeds.
... Perennial, rhizomatous forbs, including Convolvulus arvensis L. Scop. (field bindweed), have been particularly problematic for organic producers (Tautges et al., 2017b;Orloff et al., 2018). Convolvulus arvensis can reproduce through both seeds and vegetative shoots. ...
... Perennial rhizomatous weeds in organic, small grain cropping systems are difficult to manage (OAEC, 2013;DeDecker et al., 2014;Tautges et al., 2017b;Orloff et al., 2018). In this experiment, we recorded increases in mean C. arvensis density in certain annual and biennial crop rotations with minimal to moderate tillage. ...
Convolvulus arvensis L. Scop. (field bindweed) is a difficult weed to manage in organic cropping systems. Convolvulus arvensis suppression often requires intensive tillage and cultivation practices that have negative impacts on soil quality. To improve C. arvensis management in organic, small grain cropping systems, we compared ten cropping system treatments in a field trial from the autumn of 2017 until harvest of 2020 in Corvallis, MT, USA. Cropping system treatments varied along a gradient of tillage and crop competition, with tillage intensity and competition inversely related. High soil disturbance and no competition occurred in two treatments that remained in tilled fallow for two consecutive years. Six cropping system treatments had different combinations of tillage and annual or biennial crops, including wheat and forages. Two treatments had minimal soil disturbance and maximum competition from two consecutive years of perennial alfalfa. Convolvulus arvensis ramet density was counted annually to estimate changes in treatments over time. Differences in soil chemical and physical properties between treatments were also assessed in the final years of the study. In the first two years, there was no difference in C. arvensis ramet density among cropping system treatments. In the final two years of the study, C. arvensis density remained below one ramet per m ² in intensively tilled fallow treatments and perennial alfalfa treatments, but was much more variable in treatments with more diverse annual and biennial crop rotations with minimal to moderate tillage. The only differences between treatments in soil physical and chemical properties was aggregate stability. Soil from the most intensively tilled fallow treatments had lower soil aggregate stability than six other treatments, indicating higher erosion potential. Our results suggest that annual cropping systems can lead to increased C. arvensis density. Incorporating a perennial forage or an intensively tilled fallow period can prevent C. arvensis expansion in small grain organic cropping systems, but the perennial forage can protect and enhance soil quality.
... Convolvulus arvensis L. (Convolvulaceae), commonly known as field bindweed, correhuela perenne, or creeping jenny in North America, is a creeping perennial plant that is found throughout the temperate regions of the world (Wood et al. 2015). It is native to Eurasia and noted as one of the top weeds of agricultural and horticultural systems worldwide (Holm et al. 1977;Muenscher 1955). Field bindweed's twining habit can reduce crop yield and interferes with harvesting operations and it is an alternate host of viruses that attack tomato, potato, tobacco and Vaccinium (blueberries, cranberries, etc.) (Weaver and Riley 1982). ...
... Cultivation, herbicides, and biological control are used to manage field bindweed, but this plant remains difficult to control in selected habitats (Davis et al. 2018), especially organic systems (Orloff et al. 2018). Field bindweed was targeted for classical biological control in the 1980s using a gall mite and a moth (Julien and Griffith 1998), with limited establishment and impact (McCLay and De Clerck-Floate 2002;Smith et al. 2010;Winston et al. 2019). ...
Convolvulus arvensis L. (Convolvulaceae), commonly known as field bindweed, is a creeping perennial plant found throughout the temperate regions of the world. We performed genetic analysis on 634 plants from 64 populations across western North America. We found 399 distinct AFLP genotypes and none of these were shared across populations. The production of new shoots within populations was by both seed and rhizome, with reproduction by seed being slightly more common. A majority (54%) of the genetic variation was among populations, and we found two genetic clusters in the invasion that have a tendency to be predominant toward either the west or east of the invasion. Some populations appear to propagate entirely thru new ramets from rhizome, thus newly proposed root-mining biological control agents might play an important role in limiting spread of this noxious weed.
... In some cases where aggressive perennial weeds are present, it may be necessary to extend the tarp application time to several months during critical weed growth phases or a full year to break the vegetative life cycle. For example, field bindweed has extensive root storage and is often managed by frequent mechanical tillage in organic systems to reduce root reserves (Orloff et al., 2018). Canada thistle (Cirsium arvense) is another difficult weed to control due to its root storage and regrowth potential, and tillage can spread the roots, leading to further vegetative establishment (Jacobs et al., 2006). ...
... Canada thistle (Cirsium arvense) is another difficult weed to control due to its root storage and regrowth potential, and tillage can spread the roots, leading to further vegetative establishment (Jacobs et al., 2006). In a meta-analysis of control methods in organic systems, shading resulted in the greatest reduction of canada thistle; however, there were insufficient data to provide a confidence interval compared with the other methods that were included in the meta-analysis (Orloff et al., 2018). Research is needed to investigate timing and duration of tarping to control perennial weed species that have extensive root systems and root reserves. ...
Covering the soil surface with opaque plastic sheets to kill vegetation is referred to as tarping and is used by small-scale and organic growers to control weeds before planting crops. There are few published studies on tarping, and here we present a review of the literature in combination with observations from two on-farm case studies, one carried out in northern California and the other in northwestern Washington. An advantage of tarping is that it enables growers to control weeds without herbicides or tillage equipment, which can be cost-prohibitive for small-scale growers. Tarping is also suitable for no- or reduced-tillage systems, which is a primary goal for many small-scale and organic growers. Silage tarps that are 5 to 6 mils thick and black on one side and white on the other are most commonly used for tarping, are readily available new or used from some local agricultural suppliers or online, and can be reused for six or more seasons. Tarps are placed with the black side up to warm the soil, which encourages weed seed germination. When the soil is tilled and then tarped, a 3-week period with sufficient soil temperature and moisture is sufficient to kill emergent weeds in the top ≈1 inch of soil and provides a 95% to 100% weed-free surface at tarp removal. When a tarp is applied from autumn until spring to a plot that has established weeds, winter annual weeds can be controlled for several weeks after tarp removal, and then soil disturbance results in germination of additional weed seeds. For established perennial weeds, it may be necessary to extend the tarp application time to several months during critical weed growth phases or a full year to break the vegetative life cycle. Tarping does not reduce the weed seed bank, thus minimal soil disturbance after tarp removal is needed to maintain a reduced weed population during the cropping period.
... When evaluating weed communities, our results are consistent with those of Pollnac et al. [33], who found that organic small grain fields in the NGP had greater weed species richness and evenness than conventional small grain fields which, in turn, could potentially support beneficial insects such as pollinators, parasitoids, and generalists predators [6,19,34,35]. However, organic farms in the drylands of NGP may face exacerbated challenges in weed management [36,37], as the weeds are often considered impediments to agricultural production [5]. ...
... Because tillage is frequently used in organic fields, the weed communities in those systems could shift to exclude perennial grasses and favor annual forbs, as frequent soil disturbance kills perennation structures and moves seeds to more surficial layers of the soil [40,41]. However, we also observed few of the perennial weeds such as C. arvense in our organic fields, possibly suggesting an ineffectiveness of tillage to control this species, but to break its roots and further increase its abundance and spread through vegetative propagation [36]. ...
Farming systems act as ecological filters impacting cropland associated biodiversity; however, the extent of these effects is largely unknown in the drylands of the Northern Great Plains (NGP), a key conventional and organic crop production region. In this 3-year (2013–2015) on-farm study, we addressed this knowledge gap by assessing the effects of conventional and organic farming systems on weed and ground beetle (carabidae) communities. We observed 25 weed species in conventional and 44 in organic fields. Weed species richness and weed species evenness were 237% and 137% greater in organic fields than in conventional fields. We collected a total of 1520 beetle specimens, representing 28 species in conventional and 37 in organic fields. Beetle activity-density and species richness were 220% and 156% greater in organic fields than in conventional fields. Both weed and ground beetle communities differed between conventional and organic fields, indicating that farming systems act as distinct ecological filters. We conclude that, in the drylands of the NGP, adoption of organic farming enhances weed abundance which could have potential management challenges, but provide floral resources to the pollinators and parasitoids. Similarly, greater diversity of ground beetles could enhance conservation biological control of crop pests, ultimately supporting for sustainable agriculture.
... Grain yield reduction resulting from infestations of perennial creeping weeds such as Canada thistle can approach 70% (McLennan et al. 1991). Perennial weeds are difficult to manage in organic systems due to their physiological characteristics such as extensive root systems with carbohydrate reserves that enable them to resist a variety of management approaches (Orloff et al. 2018). ...
Creeping perennial weeds are difficult to manage on organic farms in semi-arid regions of the northern Great Plains. Integrated weed management practices that combine biological, cultural, and mechanical controls can improve management of these weeds, but little is known about the soil microbial response to these practices. Our work investigated the soil microbiome response to contrasting, 4-year crop sequences with standard and reduced tillage. The crop sequences included a range of crop competition phases from high (three years of alfalfa, Medicago sativa L.) to low (two years of continuous fallow), within the longer 4-year period, with intermediate levels of crop competition between those two extremes. Soil samples were collected, and bacterial 16S and fungal ITS amplicon sequencing was performed. Differences in alpha diversity were not significant (p > 0.05) between tillage methods. Across all six locations, bacterial alpha diversity was negatively correlated with soil organic matter (R = -0.37, p < 0.001) while fungal alpha diversity was positively correlated (R = 0.17, p = 0.043). Bacterial community composition was not affected by crop sequence or tillage treatment. Fungal community composition was affected by crop sequence (p = 0.00163) and tillage (p = 0.02). The fungal genera Neosetophoma, Boeremia, and Paraphoma were 10 – 35-fold more abundant in continuous alfalfa compared to the mean abundance in the other crop sequences. Reduced tillage led to a 40% reduction in the fungal genus Fusarium, which contains many plant pathogen species. These results suggest that diversified crop sequences and altered tillage methods have minimal impact on bacterial communities, but fungal communities are sensitive to these management changes.
... 9,15 Two perennials, Canada thistle [Cirsium arvense (L.) Scop.] and field bindweed (Convolvulus arvensis L.), are the most problematic weeds in regional and national organic systems. 3,5,30 Natural herbicides could play an important role in organic and conventional agriculture by reducing soil disturbance and providing new MOAs for weed management. 9,13 The improved efficacy of these new plant-derived herbicides may make them suitable for large-scale adoption. ...
BACKGROUND
Weed management is the greatest production challenge for most certified organic farmers, with few herbicides allowed on organic farms. Here, we compared the efficacy and cost of handhoeing (MECH) with a control (no weed management) and four commercially available registered organic herbicides under United States Department of Agriculture organic standards in managing Canada thistle (Cirsium arvense (L.) Scop.) and total vegetative cover in two apple (Malus domestica Borkh.) orchards. The four herbicide treatments had the following active ingredients: capric and caprylic acid (CAP), d‐limonene (LIM), acetic and citric acid (ACET), and clove and cinnamon oil (CIN). In separate greenhouse trials, Canada thistle response to CAP (at two concentrations), LIM, glyphosate (GLY), and MECH were also studied.
RESULTS
All materials reduced weed cover by 48% or more 72 h after treatment in the orchard trials; CAP performed best, reducing weed cover by 88% in 1 h and 98% in 72 h. CAP and LIM reduced early season, perennial weed cover after 3 years of repeated applications in an organic orchard; a single application of CAP and LIM would cost on average US203.50 ha⁻¹ less than MECH at US122.
CONCLUSION
Adding effective, next‐generation, natural herbicides, such as CAP and LIM, to existing weed management strategies may allow organic producers to reduce weed pressure, till less, and improve profitability, while providing conventional producers options to combat herbicide‐resistant weeds. © 2025 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
... These ecological impacts make finding effective no-till or reduced-till weed management options for semi-arid organic systems particularly important (Lehnhoff et al., 2017). Cultural methods (i.e., perennial forage crops; Gramig et al., 2024;Larson et al., 2024) have been effective, however integrated management has been proposed as the best approach (Davis et al., 2018;Orloff et al., 2018). Using fungal pathogens in combination with herbicides has increased C. arvense control (Bailey et al., 2000), and there is potential for integrating fungal biocontrol agents into organic management plans (Burns et al., 2013;Cripps et al., 2011;Davis et al., 2018;Sciegienka et al., 2011). ...
... Several additional management techniques that decrease field bindweed, including mowing, grazing, crop diversification, solarization, shading, flaming, and crop competition, have been proposed [48]. The prolonged exposure of films to weathering agents (solar radiation, high air temperature, relative humidity, etc.) and the employment of chemical substances determine progressive degradation and photo-oxidation processes with a variation of physical and mechanical properties of the films [49]. ...
The replacement of synthetic chemical herbicides and traditional plastic sheets is a major challenge of modern horticulture in view of a sustainable weed management. In the first step of this research, we tested the weed control efficacy of two biodegradable polymers, chitosan and galactomannan, applied to the soil surface as spray mulching, with or without the addition of charcoal as a light masking agent, and five essential oils with recognized herbicide properties. The results showed the ability of chitosan in reducing the number and the biomass of annual plants, regardless of the addition of charcoal and essential oils. In the second step, we tested the efficacy of one or three days of false seeding to increase the effectiveness of chitosan against seed germination. The results showed, on average, a reduction of 79% of annual weed presence after three days of false seeding. In both steps, the microbial biomass and three indicators of microbial activity (i.e., basal respiration, FDA hydrolysis activity, and D-glucosamine-induced respiration) were measured in the soil under the experiments in order to investigate possible alterations of soil biological activity induced by the treatments. The results provided no evidence of negative impact of the treatments on soil microbial biomass and activity.
... In addition, the higher the weeding action frequency is, the greater the probability of inducing crop damage. Moreover, the disturbance of the topsoil causes the loss of soil moisture and nutrients in this area, which leads to the deterioration of soil quality (Orloff et al., 2018). Therefore, the weeding device adopts a targeted weeding method to reduce its impact on crops and soil. ...
Mechanical weed control is the most promising weed control method for weed management in organic agriculture. Among the various available methods, inter-row weeding technology is relatively mature, and researchers have focused on intra-row weeding technology. The objective of this study was to develop a new intelligent intra-row mechanical robotic weeding system based on deep learning for crop and weed detection. The system consists of a mobile robot platform and two intelligent weeding units. The mobile robot platform provides power support as well as operating conditions for the weeding units. A targeted weeding pattern was proposed based on the deep learning detection results, and protected and targeted weeding zones were established by strict criteria to reduce crop injury rates. In addition, three weed control knives were designed according to different field environments. Field trials showed that among the three weed knives, the plough-surface weeding knife was the most effective and most suitable knife for flat cultivation, and the wedge weeding knife was most suitable for ridge planting. Based on the obtained results, the best weeding method was determined, and the experiment was repeated using a wedge weeding knife under ridge planting conditions. The final weed removal rate was 85.91%, and the crop injury rate was 1.17%. The results demonstrated the feasibility of the proposed intra-row weed control method.
... Convolvulus arvensis L. (field bindweed) (Orloff et al., 2018), Cuscuta campestris Yuncker (dodder) (Saric-Krsmanovic et al., 2018), R. crispus (Iqbal et al., 2019), Sorghum halepense L. Pers. (johnson grass) (Peerzada et al., 2017) and Hordeum spontaneum L. (wild barley) (Hosseini et al., 2019) are common grassland weeds and they vary in seed characteristics, such as size, shape and hardness (Hogan & Phillips, 2011). ...
Endozoochory is known as an important mechanism for the spread of weeds. We carried out experiments to assess the fate of seeds of several weed species (Convolvulus arvensis, Cuscuta campestris, Rumex crispus, Hordeum spontaneum and Sorghum halepense) after passing through the gut of sheep and goat. Eighteen animals of both sheep and goat received diet mixed with seeds
of the weed species or control with only wheat bran (five weed species+ control× three
replications). Results showed that a higher proportion of seeds were missing after passage through the sheep gut than in goats. In goats, a greater proportion of seeds were dead after passage, but the number of seeds collected from dung was also greater. Weed species differed, with the highest seed recovery and viability in Cuscuta campestris. Based on time of seed passages through the animal gut estimated for the different weed species, we recommend that sheep should be kept in a corral for 96 h to minimize seed transportation via their faeces. For goats, if R. crispus and C. arvensis seeds could be excluded from the diet, then
maintaining them for 96 h in an animal stall would ensure little seed transportation via dung, but we found R. crispus and C. arvensis seeds to be present and viable in goat dung even 120 h after feeding. Very large numbers of viable seeds can be found in goat and sheep dung, so the use of rotted manure is highly recommended to avoid transportation of viable seeds via manure fertilizers
... Many studies have been conducted on the biological control of C. arvense. Pathogens have been studied more than insects for C. arvense control, mainly in greenhouses (Lundkvist and Verwijst 2011;Orloff et al. 2018). According to these studies, the most effective agents on C. arvense are the pests Puccinia punctiformis and Sclerotinia sclerotiorum, along with the beetle Cassida rubiginosa . ...
Cirsium arvense (L.) Scop. is one of the most problematic perennial weeds in European countries, causing notable yield losses in both conventional and organic arable cropping systems. C. arvense control is essential because its infestation spreads rapidly and has negative impacts for several years due to its biological characteristics. Herbicidal treatments are the main control methods used in conventional input-based systems, but they are not always more effective than cultural practices. However, the cultural practices currently employed in arable cropping systems are often expensive and time-consuming. To guarantee the efficiency of these control practices, knowledge of C. arvense biology is essential. This review synthesizes the key points from the previous literature on C. arvense biology that can be mobilized to this end and analyzes the literature on different strategies of C. arvense control without herbicides. These strategies are (1) limitation of C. arvense dispersal, (2) weakening of root reserves, (3) extraction of roots, (4) competition with cultivated species, and (5) physical destruction. There is also a review of reported experiences using these strategies for C. arvense control, and relevant information is presented on associated biological processes to optimize the efficacy of each practice. The benefits and drawbacks of these strategies for C. arvense control are also emphasized, as well as the possibility of combining them in cropping systems, even though some knowledge gaps remain. This review confirms that one individual practice, implemented in 1 year only, is not sufficient to provide satisfactory, long-term control of C. arvense; therefore, further studies on combinations of control strategies and processes are required. There is a particular lack of knowledge about the duration of the effect of C. arvense control strategies.
... Although PRE-applied herbicides are mostly used to control bindweed seedlings, some products, like trifluralin, can suppress perennial vine emergence (Sosnoskie and Hanson 2016). Results from meta-analyses suggest that integrated practices, with or without herbicides, can be effective for managing field bindweed, although only a few studies have been conducted and few describe bindweed population dynamics over an extended time (Davis et al. 2018;Orloff et al. 2018). ...
Field bindweed (Convolvulus arvensis): “all tied up” - Lynn M. Sosnoskie, Bradley D. Hanson, Lawrence E. Steckel
... Development of more mechanistic frameworks for understanding the ecological niches and traits of cover crop species may enable the design of functionally diverse species mixtures that can ensure weed control services better than single species monocultures (Ranaldo et al. 2019). Relatively few studies in our literature search followed changes in weed pressure due to cover cropping over more than 2 years (data not shown), yet both annual and perennial weed populations can take several years to respond to management (Hiltbrunner et al. 2008;Orloff et al. 2018). Thus, increasing longterm research efforts focused on alternative weed control strategies that include cover crops will be valuable for advancing organic weed control research. ...
Organic crop systems rely on tillage as the primary means to control weeds, but negative impacts of tillage may prevent farmers from achieving the potential soil health benefits of organic management. Cover crops have been suggested as a solution for overcoming this tillage trade-off directly by enhancing soil health and indirectly by providing weed control, thus reducing the need for tillage. In order to characterize the state of published research on the effects of cover crops on weed control and soil health in organic crop systems, we conducted a formal literature search on this topic and identified 116 relevant studies which were subsequently categorized by research focus, management strategy, and variables measured. We found 83 studies examined effects of cover crops on weed control and 33 studies examined effects of cover crops on soil health, but only 10 of the studies reported on both weed control and soil health effects. The lack of integrated studies examining both weed control and soil health responses to management highlights a research gap not sufficiently addressed by researchers, even though it is a topic of great interest to many organic farmers. A majority of studies (79) included reduced or no-till treatments, and annual grasses, clover, and vetch species were the most common cover crops. Assessments of aboveground biomass were the most common weed control measurements, while soil organic matter was the most common soil health measurement. Recommendations for future research needs include the following: more integrated assessments of the effects of cover crops on both soil health and weed control under varying tillage regimes; greater effort to characterize the soil health impacts of cover crop systems utilizing newly developed soil health indicators including soil physical parameters; long-term studies to assess dynamic soil health responses as well as perennial weed pressure (particularly in reduced and no-till organic systems); and greater allocation of research funding to regions outside of North America and Europe.
... Eghball and Lesoing (2000) found out that the 8 weed seeds were inactivated if the temperature were kept at 60 C, with the exception of pie-marker herb (Abutilon theophrasti Medicus). Orloff et al. (2018) observed that field bindweed was the most difficult to eliminate. Soto-Paz et al. (2019) advised that increasing the mixing frequency would decrease the germination of all weed seeds, possibly as a result of the elevated temperature during the composting. ...
There are many weed seeds that maintain their viability in cow manure (COM), which not only poses a serious threat to agriculture if the manure is applied to the fields directly, but also affects the food security. Composting is an essential process that transforms COM into fertilizer and reduces the plant diseases or weed seeds. In the scientific literature, there are many investigations on the effect of temperature, electrical conductivity, and pH on the viability of the weed seeds, but very few reports dealt with the combined influence of the above factors with volatile fatty acids (acetic acid) and toxic metals on the deactivation of weed seeds. The aim of this study was to investigate the compost toxicity and maturity by a seed germination test. The viability of 8 types of weed seeds was investigated in separate glass fermentation tanks during the COM composting for 45 d. The seed viability was determined by the triphenyl tetrazole chloride method. The results revealed that all the weed seeds were killed in the process of composting, with 7 weed seeds inactivated within 110 h at temperatures below 60 °C, while the 8th seed, field bindweed was an exception. This could be attributed to the large volume of the seed; however, the follow-up process could destroy the field bindweed as well. The significant correlations among various physicochemical parameters, volatile fatty acids, toxic metals and viability weed seeds are found by redundancy analyses. This study could be considered a benchmark that suggests that the use of composted COM involves a small risk of enhancing the abundance of weed seeds. The aerobic composting appears to be an efficient way to treat the COM in a way that suppresses the parasitic weeds so that the COM could be applied without risking the pets.
... sepium). In a meta-analysis of perennial weed management in organic cropping systems, Orloff et al. (2018) report that although mechanical weed control was the most commonly researched method, its efficacy was variable, and it did not outperform other methods of control. Differences in sprouting activity and readiness of root and rhizome buds in relation to tillage and cultivation is another potential reason why different perennial species were dominant in different cropping systems (Brandsaeter et al. 2010). ...
Weed management is a major challenge in organic crop production, and organic farms generally harbor larger weed populations and more diverse communities compared with conventional farms. However, little research has been conducted on the effects of different organic management practices on weed communities and crop yields. In 2014 and 2015, we measured weed community structure and soybean [ Glycine max (L.) Merr.] yield in a long-term experiment that compared four organic cropping systems that differed in nutrient inputs, tillage, and weed management intensity: (i) High Fertility (HF), (ii) Low Fertility (LF), (iii) Enhanced Weed Management (EWM), and (iv) Reduced Tillage (RT). In addition, we created Weed Free sub-plots within each system in order to assess the impact of weeds on soybean yield. Weed density was greater in the LF and RT systems compared with the EWM system, but weed biomass did not differ among systems. Weed species richness was greater in the RT system compared with the EWM system, and weed community composition differed between RT and other systems. Our results show that differences in weed community structure were primarily related to differences in tillage intensity, rather than nutrient inputs. Soybean yield was lower in the EWM system compared with the HF and RT systems. When averaged across all four cropping systems and both years, soybean yield in Weed Free sub-plots was 10% greater than soybean yield in the Ambient Weed sub-plots that received standard management practices of the system in which they were located. Although weed competition limited soybean yield across all systems, the EWM system which had the lowest weed density also had the lowest soybean yield. Future research should aim to overcome such tradeoffs between weed control and yield potential, while conserving weed species richness and the ecosystem services associated with increased weed diversity.
... Probably the mowing of UVS also created better light conditions by reducing the canopy of herbaceous strata. It was shown that the abundance of Convolvulus arvensis can be reduced by shading (using shade cloth) whereas mowing has no effect or can even lead to positive response (see Orloff et al., 2018 and references therein). However, it seems that UVS are unsuitable for the conservation of rare weeds for which alternative habitats (such as conservation headlands) would need to be established in the landscape. ...
Alley cropping agroforestry is a land use practice in which arable crops are grown between tree rows. In such agroforestry systems, non-crop herbaceous vegetation develops on the tree rows, resulting in understory vegetation strips (UVS). UVS are perceived both as reservoirs for weeds and opportunities for biodiversity conservation. The purpose of this study was to assess the contribution of UVS to (i) plant spillover and (ii) plant diversity conservation, depending on their functional structure and the farming system. Vegetation surveys were carried out in May 2017 in SouthWestern France over 16 winter cereal fields (8 alley cropping agroforestry systems and 8 pure crop controls), half under conventional farming and half under organic farming. Using data on plant functional traits related to dispersal strategies and response to agricultural disturbances, we explained the mechanisms involved in plant spillover between habitats. The study revealed that very few species were able to disperse far into crop alleys, except perennial species producing rhizomes and stolons whose spread has been favored by tillage. The presence of UVS in agroforestry fields did not increase weed-crop ratio (i.e. weed coverage / weed and crop coverage) in adjacent crop alleys. On the other hand, UVS harbored richer and more abundant floras (with high proportions of species rarely found in arable habitats) compared to crop alleys and pure crop controls, especially under conventional farming. The functional approach provided insights for weed management in alley cropping agroforestry systems in order to optimize plant diversity conservation without increasing weed-crop ratio. This study showed the relevance of using the functional approach to understand the mechanisms behind plant spillover in cropping systems that integrate semi-natural habitats.
... In this study, it seems that the impact of weed presence on wheat growth was more serious at the very end of the growing season. This confirms observations from practical farming that C. arvensis, a highly competitive weed [34] and A. myosuroides are key weeds that need special caution and that the regrowth of perennial grasses needs to be avoided. ...
Reduced tillage reduces soil erosion and increases topsoil organic matter compared with conventional tillage. However, yields are often reported to be lower, presumably, due to increased weed pressure and a slower N mineralization under organic farming conditions. The effects of reduced tillage compared with ploughing on weed infestation and winter wheat performance at four different crop stages, i.e., tillering, stem elongation, flowering, and harvest, was monitored for a single season in an eleven-year-old organic long-term tillage trial. To disentangle the effects of weed presence on crop yield and potential crop performance, subplots were cleaned from weeds during the whole cropping season. Weed biomass was consistently higher under reduced tillage. Soil mineral nitrogen contents under reduced tillage management were higher, which could be explained by the earlier ley termination in autumn compared with the conventional tillage system. Nitrogen status of wheat assessed with SPAD measurements was consequently higher under reduced tillage throughout the season. At harvest, wheat biomass and grain yield were similar in both tillage systems in the presence of weeds, but 15–18% higher in the reduced tillage system when weeds were removed. The negative impact of weeds on yields were not found with conventional tillage with a low weed infestation. Results suggest that reduced tillage can provide equivalent and even higher yields to conventional tillage in organically managed winter wheat if weed management is improved and good nutrient supply is assured.
... Interestingly, recommendations from previous studies in the Great Basin mirror those advocated for integrated weed management of perennial species because they can extend the time period of herbicide control and produce synergistic effects on target plants that exceed the effects of either treatment applied alone (Miller, 2016;Orloff et al., 2018). Accordingly, because herbicide treatments only temporarily suppress crested wheatgrass growth (e.g., Bakker et al., 1997;Davies et al., 2013;McAdoo et al., 2017), applications to stable crested wheatgrass stands in consecutive years may prevent rapid recovery of plants to pretreatment levels and create a longer timeframe for desirable seeded species to establish under reduced competition (Ambrose and Wilson, 2003;Hansen, 2007). ...
Past seedings of crested wheatgrass (Agropyron cristatum [L.] Gaertn. and A. desertorum [Fisch. ex Link] Schult.) have the potential to persist as stable, near-monospecific stands, thereby necessitating active intervention to initiate greater species diversity and structural complexity of vegetation. However, the success of suppression treatments and native species seedings is limited by rapid recovery of crested wheatgrass and the influx of exotic annual weeds associated with herbicidal control and mechanical soil disturbances. We designed a long-term study to evaluate the efficacy of low-disturbance herbicide and seed-reduction treatments applied together or alone and either once or twice before seeding native species. Consecutive herbicide applications reduced crested wheatgrass density for up to 6 − 7 yr depending on study site, but seed removal did not reduce crested wheatgrass abundance; however, in some cases combining herbicide application with seed removal significantly increased densities of seeded species relative to herbicide alone, especially for the site with a more northern aspect. Although our low-disturbance treatments avoided the pitfalls of secondary exotic weed influx, we conclude that crested wheatgrass suppression must reduce established density to values much lower than 4 − 7 plants/m², a range that has not been obtained by ours or any previous study, in order to diminish its competitive influence on seed native species. In addition, our results indicated that site differences in environmental stress and land-use legacies exacerbate the well-recognized limitations of native species establishment and persistence in the Great Basin region.
... This is because the number of individuals surviving a weed management treatment can be directly related to the number of individuals initially present (Dieleman et al. 1999). Additionally, weed species composition and the presence of perennial weeds, which are usually more difficult to control in organic systems (Orloff et al. 2018), may also influence weed biomass in cover crops. ...
Cover crops are increasingly being adopted to provide multiple ecosystem services, including weed suppression. Understanding what drives weed biomass in cover crops can help growers make the appropriate management decisions to effectively limit weed pressure. In this paper, we use a unique dataset of 1764 measurements from seven cover crop research experiments in Pennsylvania (USA) to predict, for the first time, weed biomass in winter cover crops in the fall and spring. We assessed the following predictors: cover crop biomass in the fall and spring, fall and spring growing degree days between planting and cover crop termination, cover crop type (grass, brassica, legume monocultures, and mixtures), system management (organic, conventional), and tillage before cover crop seeding (no-till, tillage). We used random forests to develop the predictive models and identify the most important variables explaining weed biomass in cover crops. Growing degree days, cover crop type, and cover crop biomass were the most important predictor variables in both the fall (r² = 0.65) and spring (r² = 0.47). In the fall, weed biomass increased as accumulated growing degree days increased, which was mainly related to early planting dates. Fall weed biomass was greater in legume and brassica monocultures compared to grass monocultures and mixtures. Cover crop and weed biomass were positively correlated in the fall, as early planting of cover crops led to high cover crop biomass but also to high weed biomass. In contrast, high spring cover crop biomass suppressed weeds, especially as spring growing degree days increased. Grass and brassica monocultures and mixtures were more weed-suppressive than legumes. This study is the first to be able to predict weed biomass in winter cover crops using a random forest approach. Results show that weed suppression by winter cover crops can be enhanced with optimal cover crop species selection and seeding time.
... Additionally, a meta-analysis on downy brome (Bromus tectorum L.) management indicated that a variety of control methods reduced short-term abundance of B. tectorum, but only those that included herbicide or revegetation led to long-term control (Monaco et al. 2017). Finally, a recently completed meta-analysis of management of C. arvense and field bindweed (Convolvulus arvensis L.) in organic cropping systems showed that integrating two or more management strategies generally caused greater reductions in weed abundance than any method used alone (Orloff 2018). Meta-analyses can also identify knowledge gaps and potential ways to improve experimental approaches. ...
Although stand-alone and integrated management techniques have been cited as viable approaches to managing Canada thistle [ Cirsium arvense (L.) Scop.], it continues to impact annual cropping and perennial systems worldwide. We conducted meta-analyses assessing effectiveness of management techniques and herbicide mechanism of action groups for controlling C. arvense using 55 studies conducted in annual cropping systems and 45 studies in perennial systems. Herbicide was the most studied technique in both types of systems and was effective at reducing C. arvense . However, integrated multitactic techniques, with or without herbicides, were more effective than sole reliance on herbicides for long-term control in both annual cropping and perennial systems. A variety of management techniques such as biocontrol, crop diversification, mowing, and soil disturbance provided control similar to that of herbicide. Our results suggest that many management techniques aimed at reducing C. arvense can also improve crop yield or abundance of desired plants. This study highlights the need to devote more research to nonchemical and integrated management approaches for C. arvense control.
Temporal crop diversification could reduce pesticide use by increasing the proportion of crops with low pesticide use (dilution effects) or enhancing the regulation of pests, weeds and diseases (regulation effects). Here, we use the French National DEPHY Network to compare pesticide use between 16 main crops (dilution effect) and to assess whether temporal crop taxonomic and functional diversification, as implemented in commercial farms specialized in arable field crops, could explain variability in total pesticide use within 16 main crops (regulation effect). The analyses are based on 14,556 crop observations belonging to 1334 contrasted cropping systems spanning the diversity of French climatic regions. We find that cropping systems with high temporal crop diversity generally include crops with low pesticide use. For several crops, total pesticide use is reduced under higher temporal crop functional diversity, temporal crop taxonomic diversity, or both. Higher cover crop frequency increases total pesticide use through an increase in herbicide use. Further studies are required to identify crop sequences that maximize regulation and dilution effects while achieving other facets of cropping system multiperformance.
Creeping thistle, Cirsium arvense (L.) Scop, is one of the most common weeds in temperate climates. Frequently classified as an invasive species, it is the cause of massive herbicide and tillage use. Especially in organic systems, the plant is hard to manage. Little is known about creeping thistle being entirely edible and having diverse medicinal properties. Additionally, it has potential to be used as food preservative and provides essential ecosystem services. This systematic literature review provides evidence of creeping thistle uses from 56 peer-reviewed journals and 37 popular media references. It discusses potential uses and phytochemical properties of specific plant parts. Findings identify the stem as the most promising part for food use. Creeping thistle has elevated flavonoid (flower) and inulin (root) contents, with anti-inflammatory, antioxidant, and anti-diabetic properties respectively. The discussion contrasts the potential of creeping thistle of becoming a multi-purpose crop with its classification as a noxious weed.
Field studies were conducted to determine hazelnut tolerance to quinclorac and clopyralid and control efficacy of Canada thistle and field bindweed at three commercial orchards in western Oregon. Hazelnut cultivars evaluated included ‘Jefferson’, ‘Wepster’, and ‘McDonald’. Clopyralid at 278, 547, and 1,090 g ae ha ⁻¹ , and quinclorac at 420, 840, and 1,680 g ai ha ⁻¹ were applied once a year as basal-directed applications to trees that were one-, two, and five-years-old. Treatments were imposed in the early spring of 2019 and reapplied in 2020. In both years, treatments covered hazelnut suckers. Hazelnut injury from clopyralid and quinclorac was consistently between 0% and 13% and not different from nontreated control plants (p>0.05) between 14 d and 455 d after initial treatment. Similarly, there was no treatment effect on plant canopy index, leaf chlorophyll content, trunk cross-sectional area, internode length, or yield among treatments, even at the highest rates of clopyralid and quinclorac. In separate efficacy studies, clopyralid (278 g ae ha ⁻¹ ) resulted in 68% Canada thistle control and did not differ when clopyralid was mixed with carfentrazone (278 + 35 g ai ha ⁻¹ ) or glufosinate (278 + 1,148 g ai ha ⁻¹ ). Clopyralid-containing herbicide treatments suppressed field bindweed growth but did not kill plants even when mixed with carfentrazone or glufosinate. Quinclorac (420 g ha ⁻¹ ) alone provided 80% control of field bindweed and 93 and 98% control when combined with rimsulfuron (35 g ai ha ⁻¹ ) or carfentrazone (35 g ha ⁻¹ ), respectively. Still, all herbicide treatments resulted in similar field bindweed biomass. Results indicate that clopyralid and quinclorac are effective tools to help manage Canada thistle and field bindweed and that hazelnut can tolerate clopyralid and quinclorac at rates equivalent to 4-fold commercial use rates not affecting plant growth and yield.
La consommation excessive de sucres conduit à l’augmentation de désordres métaboliques, tels que l’obésité et le diabète. Les consommateurs souhaitent une alimentation plus saine à base de produits d’origine naturelle. Stevia rebaudiana, l’herbe sucrée du Paraguay, accumule dans ses feuilles des glycosides de stéviol (SGs) considérés comme des édulcorants naturels intenses, dont le marché est en pleine expansion au niveau mondial. Dans ce contexte, la société Oviatis implante une filière BIO de Stevia rebaudiana en Nouvelle-Aquitaine. Les objectifs de cette thèse CIFRE sont de caractériser la variabilité phénotypique d’une collection de cette espèce en vue de la mise en place future d’un programme de sélection. Les composantes du rendement, de biomasse foliaire, de quantité et qualité des SGs et de la réponse à Septoria sp. ont été finement décrites en condition de production pluriannuelle et multi-sites ou en conditions contrôlées. Ces travaux ont permis de 1) développer des outils de phénotypage métabolique, pathologique et au champ, 2) évaluer la variabilité phénotypique de cette collection de Stevia rebaudiana en condition de production et identifier les descripteurs de cette variabilité, 3) identifier les facteurs ontogéniques, abiotiques et culturaux impliqués dans la variabilité de cette collection, 4) évaluer la variabilité de réponses face à la septoriose. Ces résultats permettent d’identifier les critères de sélection de cette espèce pour une production BIO en Nouvelle Aquitaine, ainsi que des génotypes d’intérêt. Ils constituent les bases de la mise en place d’un programme d’amélioration variétale.
Organic agricultural production has become a major economic and cultural force. However, in water-limited environments the tools used for weed control and nutrient supply, namely tillage and cover crops, may not be environmentally or economically sustainable as tillage damages soil and cover crops use valuable water. Thus, a major challenge has been finding appropriate ways to minimize tillage and terminate cover crops while still controlling weeds and obtaining cover crop ecosystem services. One approach to achieve this is through the economically viable integration of crop and livestock enterprises to manage weeds and terminate cover crops. In this article we (1) review research needs and knowledge gaps in organic agriculture with special focus on water-limited environments; (2) summarize research aimed at developing no-till and reduced tillage in organic settings; (3) assess approaches to integrate crop and livestock production in organic systems; and (4) present initial results from a project assessing the agronomic and weed management challenges of integrated crop-livestock organic systems aimed at reducing tillage intensity in a water-limited environment. The goal of eliminating tillage in water-limited environments remains elusive, and more research is needed to successfully integrate tactics, such as cover crops and livestock grazing to increase organic farm sustainability.
Soil solarization in summers in Central Valley and near-coastal sites controlled bermudagrass and johnsongrass covered by polyethylene tarps. Field bindweed was also controlled during solarization, but regrowth occurred. To maximize control and reduce the "edge" effect - the regrowth of weeds at the edges of fields when they are not covered by tarps - the soil must be completely covered with intact polyethylene.
Weed management is a critically important activity on both agricultural and non-agricultural lands, but it is faced with a daunting set of challenges: environmental damage caused by control practices, weed resistance to herbicides, accelerated rates of weed dispersal through global trade, and greater weed impacts due to changes in climate and land use. Broad-scale use of new approaches is needed if weed management is to be successful in the coming era. We examine three approaches likely to prove useful for addressing current
and future challenges from weeds: diversifying weed management strategies with multiple complementary tactics, developing crop genotypes for enhanced weed suppression, and tailoring management strategies to better accommodate variability in weed spatial distributions. In all three cases, proof-of-concept has long been demonstrated and considerable scientific innovations have been made, but uptake by farmers and land managers has been extremely limited. Impediments to employing these and other ecologically based approaches include inadequate or inappropriate government policy instruments, a lack of market mechanisms,
and a paucity of social infrastructure with which to influence learning, decision-making, and actions by farmers and land managers. We offer examples of how these impediments are being addressed in different parts of the world, but note that there is no clear formula for determining which sets of policies, market mechanisms, and educational activities will be effective in various locations. Implementing new approaches for weed management will require multidisciplinary teams comprised of scientists, engineers, economists, sociologists, educators, farmers, land managers, industry personnel, policy makers, and others willing to focus on weeds within whole farming systems and land management units.
A lack of information regarding weed control, relative to conventional systems, has left organic growers largely on their own when devising weed management systems for organic crops. As interest in organic weed management increases, researchers need more information regarding the type and number of weed control practices undertaken on organic farms. A survey of certified organic growers was conducted in five states in the northwest United States to identify organic weed management programs and what grower and farm-operation characteristics were factors in weed management program design. Three types of weed management programs, with varying diversity in weed control practices, were identified. Stepwise binary logistic regression indicated that the likelihood of an organic grower using a more-diverse weed management program increased if the grower engaged in grain production and as the number of crops produced on an organic farm operation in 1 yr increased. The probability of operating a more-diverse weed management program also increased as a grower's education level increased. Organic hectarage operated was positively correlated with weed management program diversity, and with the adoption of cultural controls. Additionally, awareness of weeds as a factor causing yield loss was correlated with increased weed management program diversity. An increased awareness among researchers of the differing needs and abilities of organic growers in managing weeds on their farms will improve communication and outreach efforts when assisting growers with designing organic weed management programs.
Organic agricultural systems increase the complexity of weed management, leading organic farmers to cite weeds as one of the greatest barriers to organic production. Integrated Weed Management (IWM) systems have been developed to address the ecological implications of weeds and weed management in cropping systems, but adoption is minimal. Organic agriculture offers a favorable context for application of IWM, as both approaches are motivated by concern for environmental quality and agricultural sustainability. However, adoption of IWM on organic farms is poorly understood due to limited data on weed management practices used, absence of an IWM adoption metric, and insufficient consideration given to the unique farming contexts within which weed management decisions are made. Therefore, this study aimed to (1) characterize organic weed management systems; (2) identify motivations for, and barriers to, selection of weed management practices; and (3) generate guiding principles for effective targeting of weed management outreach. We surveyed Midwestern organic growers to determine how specified psychosocial, demographic, and farm structure factors influence selection of weed management practices. Cluster analysis of the data detected three disparate, yet scaled, approaches to organic weed management. Clusters were distinguished by perspective regarding weeds and the number of weed management practices used. Categorization of individual farms within the identified approaches was influenced by primary farm products as well as farmer education, years farming, and information-seeking behavior. The proposed conceptual model allows weed management educators to target outreach for enhanced compatibility of farming contexts and weed management technologies.
Weed management is a major constraint in organic crop production. Propane flaming combined with mechanical cultivation in a single operation could be an additional tool for weed control in organic maize. Field studies were conducted on the certified organic field at the Haskell Agricultural Laboratory of the University of Nebraska–Lincoln (UNL), Concord, NE, USA in 2010, 2011 and 2012 to evaluate the effect of flaming and cultivation within two fertility regimes (with and without manure) on the level of weed control and grain yield of organic maize. A total of 12 weed management treatments (WMTs) were applied at the 3-leaf (V3) and/or the 6-leaf (V6) growth stages of maize that included a weed-free control, weedy season-long, and 10 combinations of mechanical cultivation (inter-row), banded flaming (intra-row) and broadcast flaming (intra- and inter-row area). The treatments were applied utilizing flaming equipment developed at the UNL. All evaluated parameters (weed control, weed dry matter, crop injury, yield and yield components) indicated that there was no interaction between manure application and WMT; however, manure application increased maize yield by 1.1 t ha − 1. Overall, maize showed good tolerance to all flaming treatments averaging only 5.1% and 3.6% crop injury at 28 days after treatment in no-manure and manure plots, respectively. The best weed control was achieved with banded flaming followed by aggressive cultivation, providing over 90% weed control and yields of 7.8 t ha − 1, and flame-cultivation conducted twice as a single operation, giving 88% weed control and yields of 7.5 t ha − 1, conducted twice at the V3 and V6 growth stages. Broadcast flaming conducted twice provided 70% weed control and yielded 6.0 t ha − 1. These results suggest that flaming and cultivation applied separately or combined in a single operation, as a single trip across the field, have a potential to be used for weed control in organic maize production systems.
This study determined the potential of the tortoise beetle (Coleoptera: Chrysomelidae) to control Canada thistle (Asteraceae) in Iran. Genetic analysis of the tortoise beetle, based on mitochondrial DNA, confirmed the presence of the species in Iran. A field experiment using five insect densities (0 to 20 larvae plant−1) showed a positive correlation between the number of larvae transferred and impact. Feeding by 20 larvae reduced total biomass of Canada thistle by 78% and the number of capitula by 94%. More important, when grown in competition with wheat, four and eight egg batches (corresponding to approximately 12 and 24 larvae) per Canada thistle plant increased wheat ear weight by 46 and 82%, respectively. Host range studies with 22 crop and 21 weed species using no-choice and multiple-choice tests under laboratory and field conditions and parallel data from a field survey showed that joint feeding and oviposition were restricted to Canada thistle and a few other weed species. Limited feeding, without oviposition, was recorded on an additional seven weed species but also on safflower (10 to 15% reduction in biomass), and common sunflower (< 10%); the latter only under no-choice conditions. The growing period of either crop species, however, does not coincide with the feeding period of the tortoise beetle in the field. Findings indicate that the tortoise beetle is a promising biological control agent for Canada thistle in arable crops and grasslands in Iran. Other complementary methods will likely be needed to prevent substantial yield losses. Nomenclature: tortoise beetle, Cassida rubiginosa Müller; Canada thistle, Cirsium arvense (L.) Scop.; common sunflower, Helianthus annuus L.; safflower, Carthamus tinctorius L.; wheat, Triticum aestivum L.
Agricultural practices such as soil tillage emit greenhouse gases such as CO2 and N2O. As a consequence, reducing the tillage could both reduce greenhouse emissions and improve soil quality. In Europe about 25 % of arable land is managed under reduced tillage and no tillage, mainly using herbicides to get rid of weeds. Therefore, a major drawback for organic farmers is that the lack of herbicide and soil inversion could increase weed infestation. Here, we compared reduced tillage and conventional tillage in a 2002–2011 field experiment under organic management in Switzerland. We analyzed crop production and weed flora, with a focus on perennials and grasses. Data on yield, cover, richness, and composition of the weed flora were collected for wheat in 2003 and 2009, sunflower in 2004 and 2010, and spelt in 2005 and 2011, through two complete rotations. We found that weed abundance was 2.3 times higher under reduced tillage, though we did not observe a systematic increase with time. The average abundance of perennials almost doubled over time under reduced tillage, thus changing the community composition between tillage systems. Despite the weed increase, yields were similar for reduced tillage and conventional tillage. As a consequence, this study represents the first long-term trial under organic management showing that reduced tillage improves the environmental performance of this cropping system.
Meta-analysis is a statistical technique that allows one to combine the results from multiple studies to glean inferences on the overall importance of various phenomena. This method can prove to be more informative than common ''vote counting,'' in which the number of significant results is compared to the number with nonsignificant results to determine whether the phenomenon of interest is globally important. While the use of meta- analysis is widespread in medicine and the social sciences, only recently has it been applied to ecological questions. We compared the results of parametric confidence limits and ho- mogeneity statistics commonly obtained through meta-analysis to those obtained from re- sampling methods to ascertain the robustness of standard meta-analytic techniques. We found that confidence limits based on bootstrapping methods were wider than standard confidence limits, implying that resampling estimates are more conservative. In addition, we found that significance tests based on homogeneity statistics differed occasionally from results of randomization tests, implying that inferences based solely on chi-square signif- icance tests may lead to erroneous conclusions. We conclude that resampling methods should be incorporated in meta-analysis studies, to ensure proper evaluation of main effects in ecological studies.
Field studies were conducted to evaluate brassicaceous amendments in combination with solarization against diverse soilborne organisms in cut-flower production systems. Across a diversity of California climates, the application of broccoli (Brassica oleracea var. botrytis) did not consistently reduce populations of Fusarium spp., citrus nematode (Tylenchulus semipenetrans), or weeds. Solarization in combination with broccoli amendments did not consistently improve pest suppression in cool coastal regions, whereas solarization was an important component of suppression in the hot central valley. When the biomass of broccoli was increased from 4 to 8.4 dry tons/ha, there was a decrease in survival of weeds and citrus nematode but the effect on Fusarium spp. survival was not consistent. A horseradish (Armoracia lapathifolia) amendment reduced nematode populations compared to broccoli, but increased field bindweed (Convolvulus arvensis L.). Our research demonstrates that soilborne organisms vary greatly in their susceptibility to brassicaceous amendments. The citrus nematode was consistently suppressed by brassicaceous amendments, while the effect on Fusarium spp. and weeds was variable. To achieve consistent and reliable pest suppression in amendment-based management systems, it is essential to determine and understand the component mechanisms active against specific soilborne organisms.
Accepted for publication 10 October 2003. Published 20 November 2003.
Three strategies for controlling Cirsium arvense including (i) repeated stubble tillage with subsequent forage crop cultivation, (ii) repeated mowing of a ryegrass–clover ley and (iii) forage crop cultivation following a ryegrass–clover ley ploughed in May/June were investigated in field experiments over 3 years at the Experimental Farm for Organic Agriculture ‘Wiesengut’ in North-Rhine Westphalia, Germany. The development of C. arvense (shoot density, shoot size and ground cover) was regularly assessed on fixed standardized subplots. In the medium-term (9 months), repeated stubble tillage (i) decreased shoot density and regrowth capacity of C. arvense more effectively than a mowed ryegrass–clover ley (ii and iii). However, after 22 months, strategies (i) and (ii) resulted in a similar strong reduction of C. arvense shoot density of 95 and 97%, respectively. At this time, the efficacy of strategy (iii) (89%) was not significantly different to that of strategies (i) and (ii). After 26 months, the effect of all strategies was still apparent; however, the efficacy of strategy (iii) was significantly lower than that of strategy (ii). Generally, the different strategies showed only minor differences, thus delivering options for optimal strategies of thistle control under given specific conditions of sites and cropping systems.
Single and combined effects were studied of root length, burial depth, cutting and competition from a seasonal green manure crop on the growth and development of C. arvense from roots found in the upper soil layer. The experiment was performed under field conditions and partly repeated in a green house. The green manure consisted of a mixture of phacelia, common vetch, red clover and Italian ryegrass. Root fragments of 5 and 10 cm length were buried at 5 and 15 cm soil depth, simulating soil tillage. Use of green manure alone reduced growth of C. arvense more than any other single factor (81–99%), while root length and burial depth were more variable in their effect (0–96% reduction). Combined treatments involving both green manure, deep root burial (15 cm) and short root length (5 cm) reduced growth of C. arvense consistently by 95–100%. At the minimum regenerative capacity of C. arvense the number of leaves was 3–7 in plots with no green manure, at which time cutting had the greatest effect on regrowth the following year. The level for minimum regenerative capacity was not possible to decide for C. arvense growing in competition with green manure. Combined multiple treatments in spring, including use of green manure and mechanical operations in the upper soil layers, appear to be a potential means of reducing C. arvense infestations.
Phase out of most chemicals available for weed management renewed the interest in soil solarization as a technically effective and environmentally safe practice for lettuce weed control in hot summer areas. Properties of solarizing films and lettuce crop system may considerably affect weed control and yield response of soil solarization. Different solarizing films, including low-density polyethylene, ethylene-vinyl acetate copolymer, low-density polyethylene-ethylene-vinyl acetate coextruded and a biodegradable corn starch-based film, were evaluated in 2003 and 2004 for weed control and lettuce yield response under field and greenhouse conditions in Southern Italy. Soil solarization strongly reduced weed density and biomass in both greenhouse and in the field, with no significant differences among the tested plastic films. Most annual weeds were completely controlled by soil solarization, except amaranth, Amaranthus spp., in soil solarized with biodegradable film in the field. Emergence of mediterranean sweet-clover, Melilotus sulcatus, was stimulated by soil solarization in greenhouse. In the field, Cyprus vetch, Lathyrus ochrus, was found in solarized plots though absent in untreated soil. Perennial weeds were not affected by soil solarization, except a strong control of canadian thistle, Cirsium arvense, in the field. Lettuce yield resulted significantly higher in solarized soil than in control plots, with no significant differences among the solarizing materials. All tested materials proved to be technically effective for soil solarization in lettuce, though low resistance and short durability of biodegradable film may suggest its application mainly to soil solarization in greenhouse or in organic systems.
This book deals with the appearance and management of plants with different traits occurring as weeds on arable land. It describes and discusses matters and relationships that are important as a basis for understanding the varying occurrence of weeds in different crops and cropping systems and, at the same time, the response of different weeds to specified management measures for integrated weed management. The following topics are covered: ecological plant classification, annual and perennial crops, weed communities in vegetation succession, diverse life forms, germination, emergence and establishment, competition, plant adaptation to environmental conditions, soil tillage effects on weeds, chemical weed control, special management measures (including cover crops, mulches, biological control, plant breeding and physical weed control), and understanding the occurrence and rational management of weeds. This book will be of interest to teachers, postgraduate and undergraduate students and weed science researchers.
This book deals with the appearance and management of plants with different traits occurring as weeds on arable land. It describes and discusses matters and relationships that are important as a basis for understanding the varying occurrence of weeds in different crops and cropping systems and, at the same time, the response of different weeds to specified management measures for integrated weed management. The following topics are covered: ecological plant classification, annual and perennial crops, weed communities in vegetation succession, diverse life forms, germination, emergence and establishment, competition, plant adaptation to environmental conditions, soil tillage effects on weeds, chemical weed control, special management measures (including cover crops, mulches, biological control, plant breeding and physical weed control), and understanding the occurrence and rational management of weeds. This book will be of interest to teachers, postgraduate and undergraduate students and weed science researchers.
Concerns over environmental and human health impacts of conventional weed management practices, herbicide resistance in weeds, and rising costs of crop production and protection have led agricultural producers and scientists in many countries to seek strategies that take greater advantage of ecological processes and thereby allow a reduction in herbicide use. This book provides principles and practices for ecologically based weed management in a wide range of temperate and tropical farming systems. After examining weed life histories and processes determining the assembly of weed communities, the authors describe how tillage and cultivation practices, manipulations of soil conditions, competitive cultivars, crop diversification, grazing livestock, arthropod and microbial biocontrol agents, and other factors can be used to reduce weed germination, growth, competitive ability, reproduction and dispersal. Special attention is given to the evolutionary challenges that weeds pose and the roles that farmers can play in the development of new weed-management strategies.
Concerns over environmental and human health impacts of conventional weed management practices, herbicide resistance in weeds, and rising costs of crop production and protection have led agricultural producers and scientists in many countries to seek strategies that take greater advantage of ecological processes and thereby allow a reduction in herbicide use. This book provides principles and practices for ecologically based weed management in a wide range of temperate and tropical farming systems. After examining weed life histories and processes determining the assembly of weed communities, the authors describe how tillage and cultivation practices, manipulations of soil conditions, competitive cultivars, crop diversification, grazing livestock, arthropod and microbial biocontrol agents, and other factors can be used to reduce weed germination, growth, competitive ability, reproduction and dispersal. Special attention is given to the evolutionary challenges that weeds pose and the roles that farmers can play in the development of new weed-management strategies.
Field bindweed and Russian knapweed were grown from seed or rhizome segments under 520, 325, or 236 μmol·m –2 · s –1 photosynthetic photon flux density (PPFD) to determine vegetative and reproductive response. Flower production in both species declined with decreasing light level. Leaf area of field bindweed decreased as light level decreased, but Russian knapweed leaf area increased as light intensity decreased from 520 to 325 μmol·m –2 ·s –1 PPFD or from 520 to 236 μmol·m –2 ·s –1 . Dry matter of shoots, roots, and rhizomes of field bindweed grown from seed declined as light level decreased, but the only response of plants grown from rhizome segments was complete inhibition of rhizome production. Dry matter of Russian knapweed shoots and roots in plants grown from seed or rhizome segments decreased as light decreased. In both species the total PPFD was more important than whether low or high light level occurred first.
An isolate of Sclerotinia sclerotiorum (Lib.) de Bary collected from a Canada thistle [ Cirsium arvense (L.) Scop. # CIRAR] plant in Montana proved pathogenic on Canada thistle in field trials. In addition to attacking the thistle crown and causing wilting and death of the shoots, S. sclerotiorum also infected the root system. The high percentage of thistle shoot kill (20 to 80%) after treatment, and subsequent reduction in plant thistle density the following year, demonstrated the potential of S. sclerotiorum as a biological control agent for Canada thistle in Montana.
The preemergence efficacy of soil surface applications of a Phomopsis convolvulus granular formulation to control field bindweed seedlings was compared with its efficacy when inoculum granules were incorporated in soil. In addition, the effect of different doses of soil-applied granules was also determined. Under controlled environment conditions, incorporation of the fungal granules resulted in aboveground biomass reductions between 88 and 96%, with no significant differences observed between incorporation depths of 1.5 and 3 cm. Granule applications on the soil surface were less effective, reducing aboveground biomass 40 to 83%. In a parallel field experiment conducted over two growing seasons, however, surface applications of inoculum granules resulted in greater weed control compared with soil incorporation of the granules. In spring and summer trials conducted in 1996, surface applications resulted in a 93 and 100% aboveground biomass reduction, respectively, whereas incorporated granules reduced biomass 62 and 97%. Similar trends were observed in 1997. Different soil-applied doses of P. convolvulus did not affect the level of weed control under both controlled environment and field conditions. In 1995 and 1996 field trials, all rates used (30, 20, and 10 g 0.25 m-2 plot) resulted in substantial (90 to 100%) field bindweed aboveground biomass reductions. Findings in this study indicate that under field conditions, preemergence applications of the bioherbicide P. convolvulus on the soil surface provide effective control of field bindweed.
Field bindweed (Convolvulus arvensis) and hedge bindweed (Calystegia sepium) are noxious perennial weeds which can only partially be controlled by chemical or mechanical methods. Therefore biological control as an alternative is of increasing public and commercial interest. In this study we show that a mycoherbicide based on the fungus Stagonospora convolvuli LA39 efficiently controls bindweed infestations in three noncrop field trials conducted at different locations in two different years. It was the aim of this study to optimize the application strategy of the mycoherbicide regarding number and date of applications, as well as the application rate. It could be shown that conidia of LA39 should be applied two to five times from the beginning of May to the beginning of July, depending on the size and density of bindweed infestation. For an efficient bindweed control the mycoherbicide has to be applied at 40–160 ml m−2 and 5 × 106 conidia ml−1. Since pathogenic fungi often lose their aggressiveness upon continuous in vitro subcultivation, the influence of subcultivation on the virulence of LA39 was monitored over 30 vegetative generations. LA39 lost aggressiveness against both bindweed species between the third and the ninth vegetative generation. However, virulence of the fungus was fully restored after a single host plant contact. Thus continuous subcultivation should be avoided when using LA39 as a biocontrol agent.
In conclusion, the mycoherbicide LA39 is a promising product to control field and hedge bindweeds; it is a safe alternative to chemical herbicides with regard to product toxicity and environmental impact.
We examined effects of supplementary nitrogen on young Canada thistle stands in Alberta, Canada. Urea applied at 70 or 100 kg N ha –1 increased shoot population densities, mostly through increased root growth in the top 20 cm of soil rather than through released root bud dormancy. Nitrogen fertilization, therefore, may increase the severity of a Canada thistle infestation. In 1-yr-old stands, the number of emerged and unemerged root buds/m of root was higher near the soil surface in fertilized plots than in unfertilized plots, and no underground shoots were detected at the time of sampling. In 2-yr-old stands, more unemerged root buds/m of root were found at depths below 20 cm in fertilized plots than in unfertilized plots, and twice as many underground shoots/m of root occurred between 20 and 40 cm in fertilized plots as in unfertilized plots. However, no effect of nitrogen on the number of emerged root buds was detected. Nitrogen treatment increased shoot production only for those replanted root fragments from deeper than 60 cm in 1-yr-old stands and deeper than 160 cm in 2-yr-old stands.
Farmers view weed management and the risk of lower yields as barriers to transition from conventional to organic agriculture. The 3 years of transition before organic certification can be used to implement strategies to suppress weeds and improve soil fertility. The objective of this research was to evaluate the effects of five organic transition strategies on soil quality, weed suppression, and yield of tomato (Solanum lycopersicum) and potato (Solanum tuberosum) in the first year of organic production. The transition strategies included a tilled fallow, nontreated weedy, high diversity prairie mixture, smother crops, and vegetable rotation. Subplots with and without compost application were also included. Transition strategies affected weed density and biomass in the first organic year with the prairie strategy being the most suppressive of monocotyledonous weeds before potato. Compost application increased plant available nutrients and soil organic matter (OM). The quantity of plant available phosphorus was greatest in the fallow transition strategy (55 mg kg-1) when compost was applied, while percent soil OM was highest in the prairie (3.2%) and nontreated (3.1%) strategies in comparison with the other strategies. Compost application increased yields of potato and tomato with transition strategy affecting the number and weight of cull potato tubers. The selection of transition strategies before conversion to organic agriculture affected weed pressure, soil quality, and crop production in the first certified organic year.
A meta-analysis was conducted on field-competition experiments published in six journals over a 10-yr period. We analyzed the effects of competition on the biomass of organisms belonging to 93 species in a wide variety of habitats. Competition had a large effect overall, with a great deal of heterogeneity in that effect among organisms. There were large differences among trophic levels in competitive effects, but the relative magnitude of competition at different trophic levels was contrary to the predictions of ecological theory. Primary producers and carnivores displayed small to medium effects. In these two groups, interspecific effects did not differ from intraspecific effects, nor did effects differ in terrestrial versus aquatic habitats. The effects of competition on herbivores ranged from large effects on anurans and lotic arthropods, to medium effects on marine mollusks and echinoderms, to effects that were not statistically distinguishable from zero for terrestrial arthropods. Interspecific competitive effects among these herbivore groups were generally less than intraspecific effects. Among primary producers, the effects of competition were not different in high- and low-productivity habitats. Across all taxa, large organisms did not experience greater competitive effects than small organisms, and competitive effects did not depend on the size attained in the absence of competitors. The effects of competition were weakly density-dependent in cases in which it was possible to examine the effects of the density of neighbors. Experiments conducted on caged organisms resulted in greater competitive effects than those with free-roaming and unenclosed organisms. Experiments with small sample sizes, short durations, and poor experimental design were more variable than experiments that were larger, longer, and better planned.
Small plot field tests were conducted in Washington County, AR, and Phillips County, CO, to determine the efficacy of Phoma proboscis conidia in control of field bindweed (Convolvulus arvensis) under various temperature and moisture conditions during 1990-1993. Treatments included combinations of conidia with a formulation of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-(2-methyl-4-chlorophenoxy)propionic acid (MCPP) used at a sublethal dose of 18 g a.i./ha, the surfactants Activate 9-0 or Activate Plus, corn oil, or sodium alginate. Dew periods of less than 6 hr or temperatures less than 10°C or approaching 32°C were inhibitory to the infection process required for field bindweed control. A rate of 107conidia per milliliter in combination with a sublethal dose of 2,4-D and MCPP increased disease to the level achieved with 108 conidia per milliliter and controlled field bindweed. The 108 conidia per milliliter rate in combination with a sublethal dose of 2,4-D and MCPP killed mature field bindweed tissue during the later part of the growing season (31 July and 4 September 1992) when dew periods were adequate (8 10 hr). Air-dried conidia were as effective as fresh conidia in causing disease. Nylon membranes and field bindweed stems infested with P. proboscis were buried at 1-, 10-, and 20-cm depths at the Arkansas field site and recovered monthly during the winters of 1991-1992 and 1992 1993. No significant difference was found in fungal survival due to depth of burial. Higher winter survival frequencies in the second year were associated with 2 4 C lower average monthly soil temperatures relative to the first year. Survival frequency was higher on membranes than on stems.
Weed management is a major constraint in organic crop production. Propane flaming
combined with mechanical cultivation in a single operation could be an additional tool
for weed control in organic maize. Field studies were conducted on the certified organic
field at the Haskell Agricultural Laboratory of the University of Nebraska–Lincoln
(UNL), Concord, NE, USA in 2010, 2011 and 2012 to evaluate the effect of flaming
and cultivation within two fertility regimes (with and without manure) on the level of
weed control and grain yield of organic maize. A total of 12 weed management
treatments (WMTs) were applied at the 3-leaf (V3) and/or the 6-leaf (V6) growth
stages of maize that included a weed-free control, weedy season-long, and 10
combinations of mechanical cultivation (inter-row), banded flaming (intra-row) and
broadcast flaming (intra- and inter-row area). The treatments were applied utilizing
flaming equipment developed at the UNL. All evaluated parameters (weed control,
weed dry matter, crop injury, yield and yield components) indicated that there was no
interaction between manure application and WMT; however, manure application
increased maize yield by 1.1 t ha21. Overall, maize showed good tolerance to all
flaming treatments averaging only 5.1% and 3.6% crop injury at 28 days after treatment
in no-manure and manure plots, respectively. The best weed control was achieved with
banded flaming followed by aggressive cultivation, providing over 90% weed control
and yields of 7.8 t ha21, and flame-cultivation conducted twice as a single operation,
giving 88% weed control and yields of 7.5 t ha21, conducted twice at the V3 and V6
growth stages. Broadcast flaming conducted twice provided 70% weed control and
yielded 6.0 t ha21. These results suggest that flaming and cultivation applied separately
or combined in a single operation, as a single trip across the field, have a potential to be
used for weed control in organic maize production systems.
1. The number of published meta-analyses in plant ecology has increased greatly over the last two
decades. Meta-analysis has made a significant contribution to the field, allowing review of evidence
for various ecological hypotheses and theories, estimation of effects of major environmental drivers
(climate change, habitat fragmentation, invasive species, air pollution), assessment of management
and conservation strategies, and comparison of effects across different temporal and spatial scales,
taxa and ecosystems, as well as research gap identification.
2. We identified 322 meta-analyses published in the field of plant ecology between 1996 and 2013
in 95 different journals and assessed their methodological and reporting quality according to standard
criteria. Despite significant recent developments in the methodology of meta-analysis, the quality
of published meta-analyses was uneven and showed little improvement over time.
3. We found many cases of imprecise and inaccurate usage of the term ‘meta-analysis’ in plant ecology,
particularly confusion between meta-analysis and vote counting and incorrect application of
statistical techniques designed for primary studies to meta-analytical data, without recognition of the
violation of statistical assumptions of the analyses.
4. Methodological issues for meta-analyses in plant ecology include incomplete reporting of search
strategy used to retrieve primary studies, failure to test for possible publication bias and to conduct
sensitivity analysis to test the robustness of the results, as well as lack of availability of the data set
used for the analyses.
5. The use of meta-analysis is particularly common in community ecology, ecophysiology and ecosystem
ecology, but meta-analyses in ecophysiology are more likely not to meet standard quality criteria
than papers in other subdisciplines. Fewer meta-analyses have been conducted in plant
population ecology.
6. Synthesis. Over the past two decades, plant ecologists have embraced meta-analysis as a statistical
tool to combine results across studies, and much has been learned as a result. However, as the popularity
and usage of meta-analysis in the field of plant ecology has grown, establishment of quality
standards, as has been done in other disciplines, becomes increasingly important. In order to
improve the quality of future meta-analyses in plant ecology, we suggest adoption of a checklist of
quality criteria for meta-analysis for use by research synthesists, peer reviewers and journal editors.
Canada thistle poses a particular threat to organic producers in temperate agriculture due to its ability to reproduce through an extensive system of underground roots. The Canada thistle life cycle, growth, and development are seasonally affected, and exploiting this biology may be useful for weed management. The objective of this study was to evaluate smother crop mixtures, seeded at different times, for Canada thistle control. Field trials were established in 2009 and 2010 to evaluate the ability of smother crop mixtures to suppress Canada thistle growth and development. Canada thistle aboveground biomass was suppressed 50% in 2009 and 87% in 2010 by the sorghum—sudangrass mixture, averaged over planting times. The oat mixture suppressed annual weed biomass more than 58% in 2009 and 67% in 2010 in all planting dates. Percent cover of Canada thistle was affected by crop mixture in 2009 and 2010, with sorghum—sudangrass being the most suppressive. The sorghum—sudangrass mixture was more suppressive of Canada thistle, probably because it included soybean and sunflower, all high-biomass, competitive crops. Planting date affected smother crop suppression of Canada thistle growth, but the effect was not consistent between 2009 and 2010 due to differences in weather conditions.
A meta-analysis is a statistical treatment of a dataset derived from a literature review. Meta-analysis appears to be a promising approach in agricultural and environmental sciences, but its implementation requires special care. We assessed the quality of the meta-analyses carried out in agronomy, with the intent to formulate recommendations, and we illustrate these recommendations with a case study relative to the estimation of nitrous oxide emission in legume crops. Eight criteria were defined for evaluating the quality of 73 meta-analyses from major scientific journals in the domain of agronomy. Most of these meta-analyses focused on production aspects and the impact of agriculture activities on the environment or biodiversity. None of the 73 meta-analyses reviewed satisfied all eight quality criteria and only three satisfied six criteria. Based on this quality assessment, we formulated the following recommendations: (i) the procedure used to select papers from scientific databases should be explained, (ii) individual data should be weighted according to their level of precision when possible, (iii) the heterogeneity of data should be analyzed with random-effect models, (iv) sensitivity analysis should be carried out and (v) the possibility of publication bias should be investigated. Our case study showed that meta-analysis techniques would be beneficial to the assessment of environmental impacts because they make it possible to study between site-year variability, to assess uncertainty and to identify the factors with a potential environmental impact. The quality criteria and recommendations presented in this paper could serve as a guide to improve future meta-analyses made in this area.
Canada thistle is a perennial spreading weed that is difficult to control in farming systems with reduced reliance upon herbicides for weed management. Experiments were conducted from 2006 to 2008 at Champaign, IL, to evaluate the combined effects of summer annual cover crops and mowing on Canada thistle growth and survival. Whole plot treatments were fallow, buckwheat, sudangrass-cowpea mixture (MIX), and sudangrass. The subplot treatments were mowing frequencies (0 to 2 times). Cover crop and mowing did not interact to suppress Canada thistle. MIX and sudangrass produced more standing biomass, greater regrowth, and more surface mulch following mowing than the buckwheat. A single season with sudangrass or MIX reduced Canada thistle shoot density and mass to less than 20% of the initial values through two growing seasons. Mowing alone only Suppressed Canada thistle shoot density and mass on the site with greater initial density. A sudangrass or MIX cover crop alone or combined with mowing suppresses Canada thistle, but intensive management must continue for several years to eliminate patches.
An experiment was conducted in sheep-grazed pasture in three regions of New Zealand over three years to evaluate the effect of application time on the efficacy of a dry granule myceliumon-wheat formulation of Sclerotinia sclerotiorum for the biological control of Cirsium arvense . At each site, the experimental mycoherbicide was applied to a previously untreated plot in each month of the year for three years at a dose of 50 g m -2 . Applications made during the spring and early summer months of October, November and December significantly reduced the ground cover of C. arvense for 67, 67 and 44%, respectively of these applications. Reduced ground covers ranged from 38 to 81% of the cover on untreated plots. Applications in late summer and autumn were less effective. Correlations of ground cover by C. arvense with climate parameters suggested that free moisture promoted treatment efficacy, but that intense rainfall after treatment reduced efficacy through wash off. The importance of leaf wetness for the efficacy of the mycoherbicide was confirmed by comparing disease development and mortality in C. arvense shoots with and without enhanced moisture levels under field conditions. A water miscible formulation applied as a slurry was less dependent upon leaf wetness than the dry granule formulation.
Organic producers rank weeds as the most important pests that limit their crop production. In order to optimize the use of propane flaming as a weed control tool, the objective of this study was to test tolerance of selected weed species to broadcast flaming performed at different growth stages. Six annual species, including one grass [barnyardgrass (Echinochloa crus-galli)] and five broadleaves [field bindweed (Convolvulus arvensis), kochia (Kochia scoparia), ivyleaf morning glory (Ipomoea hederacea), velvetleaf (Abutilon theophrasti) and Venice mallow (Hibiscus trionum)] were flamed at three growth stages with six doses of propane. The propane doses applied were 0, 12, 31, 50, 68 and 87 kg/ha. Flaming treatments were applied utilizing a custom built flamer mounted on a four-wheeler moving at a constant speed of 6.4 km/h. Species response to propane were described by log-logistic models based on visual injury ratings and dry matter (DM) for each weed species. Overall response to flaming varied among species, growth stage and propane dose. Broadleaf weeds were more susceptible to flaming than the grass regardless of the growth stage. A dose of 76 kg/ha of propane was needed to obtain 90% DM reduction for 7-leaf (L) barnyardgrass compared to much lower doses of 40, 49, 55, 56 and 51 kg/ha propane for 8-L bindweed, 6-L kochia, 10-L morning glory, 7-L velvetleaf and 5-L Venice mallow, respectively. Moreover, the tolerance of both grassy and broadleaf weed species to broadcast flaming increased with increase in plant size. A 90% DM reduction in velvetleaf was obtained with 42, 56 and 102 kg/ha of propane for 5-L, 7-L and 16-L stages, respectively. The tested broadleaf weed species were effectively controlled (90% DM reduction) with propane dose of 30–60 kg/ha when flamed at early growth stages (3-L to 14-L), while the same dose of propane provided only 80% DM reduction in barnyardgrass when flamed at vegetative stages (4-L to 7-L). It was not possible to obtain 90% DM reduction in barnyardgrass when flamed at flowering stage with the propane doses tested in this experiment.
Cassida rubiginosa (Müller) (Coleoptera: Chrysomelidae) adults laid eggs on Canada thistle where they were released, regardless of thistle density. Densities of C. rubiginosa and plant development varied within a field and between patches of Canada thistle in natural populations. Ramets infected with the rust disease, Puccinia punctiformis (Strauss) Röhl. (Uredinales: Pucciniaceae), were not more attractive than healthy ramets to C. rubiginosa. Ramets systemically infected with the rust disease did not bloom and suffered high mortality. Eucelatoria dimmocki (Aldrich) (Diptera: Tachinidae) and Itoplectis conquisitor (Say) (Hymenoptera: Ichneumonidae) parasitized C. rubiginosa larvae. Spilochalcis side (Walker) (Hymenoptera: Chalcididae) emerged from pupae. No parasitoids were found attacking oothecae.
Different chemical, physical, and biological properties of a soil interact in complex ways that determine its potential fitness or capacity to produce healthy and nutritious crops. The integration of these properties andine resulting level of productivity often is referred to as “soil quality.” Soil quality can be defined as an inherent attribute of a soil that is inferred from its specific characteristics and observations (e.g., compactability, erodibility, and fertility). The term also refers to the soil's structural integrity, which imparts resistance to erosion, and to the loss of plant nutrients and organic matter. Soil quality often is related to soil degradation, which can be defined as the time rate of change in soil quality.
Soil quality should not be limited to soil productivity, but should encompass environmental quality, human and animal health, and food safety and quality. There is inadequate reliable information on how changes in soil quality directly affect food quality, or indirectly affect human and animal health. In characterizing soil quality, biological properties have received less emphasis than chemical and physical properties, because their effects are difficult to measure, predict, or quantify. Improved soil quality often is indicated by increased infiltration, aeration, macropores, aggregate size, aggregate stability, and soil organic matter, and by decreased bulk density, soil resistance, erosion, and nutrient runoff. These are useful, but future research should seek to identify and quantify reliable and meaningful biological/ecological indicators of soil quality, such as total species diversity or genetic diversity of beneficial soil microorganisms, insects, and animals.
Because these biological/ecological indexes of soil quality are dynamic, they will require effective monitoring and assessment programs to develop appropriate databases for research and technology transfer. We need to know how such indexes are affected by management inputs, whether they can serve as early warning indicators of soil degradation, and how they relate to the sustainability of agricultural systems.
Sans FX, Berner A, Armengot L & Mäder P (2011). Tillage effects on weed communities in an organic winter wheat–sunflower–spelt cropping sequence. Weed Research51, 413–421.
Conservation tillage could provide environmental benefits to organic farming. However, potential weed problems often tend to discourage farmers from adopting it. The effects of tillage (reduced vs. conventional), fertilisation (slurry vs. manure compost) and the application of biodynamic preparations (with and without) on crop yield and on weed cover, diversity and biological attributes were investigated in a cropping sequence of wheat, sunflower and spelt. Total weed cover and perennial cover in reduced tillage treatments were two to three times greater than in conventional treatments. Monocotyledon cover in reduced tillage was three times that in conventional tillage in spelt, whereas the dicotyledon Stellaria media dominated in sunflower. Weed diversity was similar across treatments, regardless of cereal crop, whereas lower diversity values were observed with reduced tillage in sunflower, because of the dominance of S. media. There was virtually no effect of fertilisation and biodynamic preparations on weed parameters. Although wheat and spelt yield decreased in reduced tillage plots (14% and 8% respectively), the sunflower grain yield was unaffected. Reduced tillage could thus be useful in organic cropping systems but would require proper management of perennial and monocotyledonous weeds, which are often problematic for annual crops.
The crop system implemented on organic farms requires that crop residues are incorporated into the soil following the end of wheat cultivation. This system leads to a reduction in soil moisture and the creation of favourable conditions for the emergence of weeds. In contrast, covering the soil with 60 % crop residues was found to maintain soil moisture and lead to a reduction in dry weed mass, population density and population frequency as well as a reduction in population diversity, regardless of the initial weed flora before the implementation of different soil tillage systems. Finally, an increase in the prevalence of broad-leafed weeds was observed as the level of soil cover increased.
Relation of root reserves to control of European bindweed Convolvulus arvensis L
- A L Bakke
- W Gaessler
- W E Loomis
Bakke, A.L., Gaessler, W., Loomis, W.E., 1939. Relation of root reserves to control of
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Cirsium arvense (L.) Scop. in arable farming: establishment of plants and genetic diversity
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Hettwer, U., Fan, Z., Dau, A., Gerowitt, B., 2002. Cirsium arvense (L.) Scop. in arable
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Control Canada thistle for greater profits
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Results of bindweed control experiments at the fort hays branch station
- F L Timmons
Timmons, F.L., 1941. Results of bindweed control experiments at the fort hays branch
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