Weed Invasion Research Articles

Phytotoxic and Cytogenetic Assessment of Glycerol Triazole Derivatives in Model Plants and Weeds.

Weed invasion represents a challenge for farmers, who typically manage it with herbicides. However, this approach raises concerns about environmental and human health, as well as increasing resistance in these plants with continued use. Therefore, exploring alternative methods, such as heterocyclic compounds, triazoles, is essential due to their biological and environmental relevance. This study aimed to evaluate the effects of twelve 1,2,3-triazoles on the germination and early development of Lactuca sativa, Bidens pilosa, and Lolium multiflorum, as well as their impact on cell division in the cells of L. sativa. Triazole derivatives 4a, 4b, 4c, 4g, 4h, 4i, 4k, and 4l exhibited phytotoxicity, showing varying levels of inhibition in germination, germination speed index, and root growth. Chlorinated compounds were the most detrimental to lettuce development. B. pilosa was notably affected by compounds 4h, 4i, 4k, and 4l, while L. multiflorum responded most to triazoles 4c and 4l, with effectiveness comparable to that of the herbicide glyphosate. All derivatives, except 4l, exhibited aneugenic mechanisms of action, and 4a, 4b, 4c, 4e, 4f, and 4g showed clastogenic effects. This study demonstrated the potential of triazoles as effective agents against weed growth, with mechanisms that warrant further investigation for agricultural applications.

Effects of alligator weed invasion on wetlands in protected areas: A case study of Lishui Jiulong National Wetland Park

Wetlands are one of the ecosystems most easily and severely invaded by alien species. Biological invasions can have significant impacts on local plant communities and ecosystem functioning. While numerous studies have assessed the impacts of biological invasions on wetlands, relatively few have been conducted in protected areas such as national wetland parks. We conducted a field survey to investigate the effects of the invasive herb Alternanthera philoxeroides (alligator weed) on the productivity and structure of plant communities and soil microbial communities in the Lishui Jiulong National Wetland Park in Zhejiang, China. We also examined the potential influence of the distance to the river edge on the impact of the alligator weed invasion. The alligator weed invasion significantly altered the plant community structure. It reduced the coverage of co-occurring plant species, including native (−31.2 %), invasive (−70.1 %), and non-invasive alien plants (−58.4 %). However, it increased species richness by 50 %, Pielou's evenness by 20 %, and Simpson's diversity index by 29.1 % for the overall plant community. Furthermore, within the community not invaded by alligator weed, increasing the distance to the river edge decreased the number of native plants by 57.0 % and the aboveground biomass of other invasive plants by 78.6 %. Contrary to expectations, no effects of the alligator weed invasion were observed on soil fungal and bacterial communities. Therefore, the impacts of the alligator weed invasion varied with spatial context and plant category, emphasizing the need to consider multiple scales and environmental factors when assessing the effects of invasive species on plant biodiversity. These insights enhance our understanding of plant invasions in wetlands and can guide the development of effective management strategies for these important ecosystems.

Biological potential of plant pathogenic fungi on weeds: A mini-review essay

The invasion of weeds into productive areas has substantial negative effects on native ecosystems as well as agricultural production systems globally. Consequently, the task of maintaining or restoring these systems will become increasingly challenging without consistent, ongoing management efforts. The intensifying emergence of herbicide resistance in numerous weed species, coupled with the unintended pollution caused by synthetic herbicides, underscores the growing necessity for alternative, environmentally friendly, and sustainable management techniques, such as the utilisation of bioherbicides. Plant pathogenic microbes play an important role in biologically management of weeds, with the utilization of plant pathogenic fungi emerging as a promising area of study for novel research trends aimed at weed management without reliance of herbicides and to mitigate environmental pollution. A potential solution to decreasing pesticide usage involves the development of bioherbicides containing fungal active ingredients. Among the most commonly utilised fungi in bioherbicides are genera like Alternaria, Colletotrichum, Cercospora, Fusarium, Phomopsis, Phytophthora, Phoma, and Puccinia. Increased weed resistance to herbicides has influenced new strategies for weed management, with some fungi from genera such as Colletotrichum and Phoma already employed for weed control. Nonetheless, it is evident from reviews that further research is imperative in this domain, with particular emphasis on analysing the efficacy of each plant pathogenic fungi.

Effect of Irrigation Regime and Soil Nutrients on the Growth of the Paddy Weed Heteranthera reniformis and Rice Grain Yield

The growth of Heteranthera reniformis, an invasive alien paddy weed, can be affected by cultivation practices. The experiments were conducted using herbicide-free soil to understand the effects of irrigation regimes and nutrient treatments on the growth of H. reniformis, as well as yield parameters while competing with a pre-existing seedbank. The pot experiments were conducted in a randomized complete block design (RBCD) with three replicates and twelve treatments. The four irrigation regimes (IRs): continuous irrigation (CI), soil condition at near saturation (non-puddled) (S), alternate wetting and drying (AWD) irrigation under two conditions [rewatered when the soil water potential reached −25 kPa (25P) and −35 kPa (35P)], and three nutrient treatments (NTs) of 0–0–0 NPK (NT0), 40–25–30 NPK (NT1), 80–50–60 NPK (NT2), kg ha−1 were established. The IRs had a significant effect on the growth of H. reniformis and other paddy field weeds, and the growth of H. reniformis was suppressed in the AWD regimes. NT2 resulted in more rice panicles, higher grain yield, and increased irrigation water use efficiency (IWUE). The highest grain yield and protein content were observed in S–NT2 and 25P–NT2 treatments. The IR and NT can be maintained to prevent yield penalties and reduce the invasiveness of weeds.

Seed Bank Distribution of Kongwa Weed (Astripomoea Hyoscyamoides) for Different Land Use Types in Kongwa District, Tanzania

Weed invasion poses significant challenges to agriculture and ecosystems, leading to substantial economic losses globally. Astripomoea hyoscyamoides Vatke Verdc. commonly known as Kongwa weed, is a highly invasive species causing a severe infestation in the Kongwa district, Tanzania. This study investigated the seed bank distribution of Kongwa weed across different land use types, specifically arable land, fallow land, and range land in the Kongwa district. Soil samples were collected from chamae, chigwingwili, chimotolo, machenje, msunjulile, ndalibo, nyerere, and sejeli villages, representing range, arable, and fallow land, at different soil depths (0-5 cm, 5-10 cm, 10-15 cm, and 15-20 cm). The results showed significant variations in Kongwa weed seed density among villages, with Msunjulile exhibiting the highest density across all land use types (1.92 seeds/m2 in arable, 6.67 seeds/m2 in fallow, and 9.83 seeds/m2 in range land). In comparison, Chigwingwili displayed the lowest density (0.33 seeds/m2 in arable land) The study revealed a decline in seed density with increased soil depth, with the topsoil (0-5 cm) showing the highest seed density. Also, range land exhibited the highest seed density, while arable and fallow land were comparable. Generally, kongwa weed seeds are observed to be higher in range land with a depth of 0–5 cm, particularly in areas near ranch areas. Implementing control measures, especially before the flowering stage, is crucial to mitigating the kongwa weed invasion. Further research on seed germination patterns is recommended to enhance weed management strategies.

A global review on arid zone restoration: approaches and challenges

Arid environments have become degraded in recent times through human activity highlighting the need for restoration works to reverse this trend. One of the most common forms of restoration works is revegetation. However, revegetation is difficult in the arid zone due to a combination of environmental factors such as low moisture and extreme temperatures, as well as financial and administrative factors. In this review, we investigated the literature describing various methods available for arid revegetation, and assess their utility for revegetation activities. Each of the methods investigated were found to have potential advantages and disadvantages, though some general trends were observed. Two main planting methods were identified, “out‐planting” and “direct seeding.” Which of these methods to use depends on the conditions of the project being undertaken. Out‐planting appeared to be the most suited approach to smaller scale projects with higher budget availability, whereas direct seeding was more suited to large scale, lower budget projects. Weed control prior to planting was identified as being critical for success in most works, whereas soil ripping was beneficial for direct seeding projects. Among the soil amendments investigated, water‐holding gels were most likely to be beneficial, whereas fertilizers were riskier due to their potential to reduce drought tolerance and increase weed invasion. Microbial inoculation with mycorrhiza showed high potential to improve plant performance but may be held back by the lack of suitable commercial sources. Newer seed technologies, such as synthetic seed coats and pellets, show promise, but this issue still requires further research and development.

Characterization of the Microbial Community Structures, Soil Chemical Properties, and Enzyme Activity of Stellera chamaejasme (Thymelaeaceae) and Its Associated Forages in Alpine Grassland of Northwestern China.

The invasion of toxic weeds was detrimental to the growth of original vegetation and speed up the degraded grasslands. The purpose of this study was to explore the difference in microbial community, soil physicochemical properties, and enzyme activity in the rhizosphere of Stellera chamaejasme and its associated forages (Stipa purpurea and Polygonum viviparum). The rhizosphere soil microbial communities of S. chamaejasme and its associated forages were determined by high-throughput sequencing technology, the physicochemical properties, and enzyme activities were also measured using soil chemical methods. We performed biological statistical analyses to explore the correlation of rhizosphere micro-ecological environment between the invading poisonous herb S. chamaejasme and its associated forages. The Ascomycota community in the rhizosphere soil of S. chamaejasme was significantly decreased when compared with its associated forages. S. chamaejasme and S. purpurea had a similar bacterial composition, while the rhizosphere of P. viviparum was associated with more Acidobacteria and Bacteroidetes. The RDA analysis showed S. chamaejasme had highly correlated with acid proteinase, invertase, polyphenol oxidase, cellulose, and neutral protease and S. purpurea had highly associated with N-acetyl-beta-D-glucosaminidase, β-D-Glucosidase, and the P. viviparum had highly associated with total phosphorus, total nitrogen, ammonium nitrogen, soil organic matter, pH, acid phosphatase, and catalase. Along with the invasion of S. chamaejasme, the microbial composition, soil physicochemical properties, and enzyme activity of the growing area changed considerably compared with the associated forages. Taken together, our results suggested that the composition and diversity of microbial communities associated with S. chamaejasme and its associated forages exhibited different patterns, and the rhizosphere soil microbial communities in different plants were regulated by different environmental factors in this alpine grassland ecosystem.

36 Beyond Environmentally Adapted, Towards Ecologically Purposed: Sheep Production in the Us West

Abstract Consumer demand for sheep products is robust, the annual consumption of U.S. lamb is steadily rising, and the number of U.S. sheep farms is increasing. Nevertheless, the U.S. sheep industry continues to lose market share to foreign competitors and the breeding ewe inventory has declined 30% since 2002. This decline has been more drastic in the upper U.S. Mountain West states, where ewe inventories have declined 37% compared with the national average decline of 26%. This is problematic given the Mountain West generates one-third and one-half of the total U.S. lamb crop and wool revenue, respectively. This depopulation trend indicates obstacles unique to the Mountain West, which are not experienced elsewhere in the nation. Mountain West sheep production systems depend on both private and public rangelands for grazing, which must co-exist with many other goals for public lands, including species conservation and critical wildlife habitat. Extensive conversion of native rangeland to croplands, rural housing, and degraded grasslands has simultaneously resulted in a substantial loss of wildlife habitat, thus creating competing ideologies for how remaining rangelands should be managed. Accordingly, public land management agencies are constantly pressured to change land management plans to accommodate public agendas aimed at restricting or halting livestock grazing on public lands with the assumption wildlife habitat will automatically improve. Such exclusion of grazing from public lands has negatively impacted operational capacity of sheep ranches, thus posing serious threats to the U.S. sheep industry and its contributions towards national food security, rural communities, and rangeland conservation. Therefore, to maintain grazing access to public lands, sheep producers and land managers urgently need tools (e.g., management, genetic) to optimize both conservation and production outcomes synergistically. However, ecological and sheep genetic outcomes have thus far been considered separate rather than integrated goals. Traditional genetic improvements in sheep production are focused strictly on the sheep without regard to the ecological outcome. In other words, the “ecosystem” is only considered to achieve profitable production within that environment. With this in mind, can sheep research move beyond the traditional focus of “environmentally adapted” flocks to “ecologically purposed” flocks? We propose that heritable ecologically focused traits can be identified and used to complement the overall sheep genetic improvement goals of the industry while creating precision-based solutions for sustainable habitat management, such as mitigating catastrophic wildfire risk, halting noxious weed invasion, and shaping vegetative structure of native plant communities towards desirable rangeland and conservation goals. We believe such outcomes extend beyond shaping public opinion about sheep grazing but also towards introducing novel value-based marketable products from the sheep industry.

Mass multiplication of Trichoderma asperellum on conifer needles and weed foliage

The impact of hazard by chemical fungicides has necessitated the development of safe and eco-friendly bio-fungicides. Trichoderma asperellum is one of the potent biocontrol agents and for its cost-effectiveness large scale production on several agricultural and industrial wastes has been tested so far. Forest fire due to highly inflammable pine needles and invasion of weeds are considered as a major cause of biodiversity loss in forests of NW Himalaya. Therefore, in the present work, the potential of forest wastes like needles of five conifer species and foliage of three noxious weeds along with some commonly used substrates were evaluated for the mass production of T. asperellum. Amongst all the screened substrates, the highest spore count was recorded on Pinus roxburghii needle powder supplemented with yeast extract and potato dextrose broth. Therefore, authors recommend the use of P. roxburghii needles for the mass multiplication of Trichoderma species as a replacement for useful agro-wastes.

Weed Detection in Rainfed Maize Crops Using UAV and PlanetScope Imagery

Weed invasion of crop fields, such as maize, is a major threat leading to yield reductions or crop right-offs for smallholder farming, especially in developing countries. A synoptic view and timeous detection of weed invasions can save the crop. The sustainable development goals (SDGs) have identified food security as a major focus point. The objectives of this study are to: (1) assess the precision of mapping maize-weed infestations using multi-temporal, unmanned aerial vehicle (UAV), and PlanetScope data by utilizing machine learning algorithms, and (2) determine the optimal timing during the maize growing season for effective weed detection. UAV and PlanetScope satellite imagery were used to map weeds using machine learning algorithms—random forest (RF) and support vector machine (SVM). The input features included spectral bands, color space channels, and various vegetation indices derived from the datasets. Furthermore, principal component analysis (PCA) was used to produce principal components (PCs) that served as inputs for the classification. In this study, eight experiments are conducted, four experiments each for UAV and PlanetScope datasets spanning four months. Experiment 1 utilized all bands with the RF classifier, experiment 2 used all bands with SVM, experiment 3 employed PCs with RF, and experiment 4 utilized PCs with SVM. The results reveal that PlanetScope achieves accuracies below 49% in all four experiments. The best overall performance was observed for experiment 1 using the UAV based on the highest mean accuracy score (>0.88), which included the overall accuracy, precision, recall, F1 score, and cross-validation scores. The findings highlight the critical role of spectral information, color spaces, and vegetation indices in accurately identifying weeds during the mid-to-late stages of maize crop growth, with the higher spatial resolution of UAV exhibiting a higher precision in the classification accuracy than the PlanetScope imagery. The most optimal stage for weed detection was found to be during the reproductive stage of the crop cycle based on the best F1 scores being indicated for the maize and weeds class. This study provides pivotal information about the spatial distribution of weeds in maize fields and this information is essential for sustainable weed management in agricultural activities.

Ecological shocks and children’s school attendance and farm work in Ghana

Accelerating the education of children and reducing child labor in agriculture remains an important development pathway to preventing intergenerational poverty and achieving the sustainable development goals. While several studies have analyzed the impact of ecological stressors on yield, income, and food security, there is limited understanding of the linkages of prevailing ecological shocks to child education and farm work. In this paper, we examine the effect of ecological shocks of pest and weed invasion on children’s school attendance and working hours on the farm using the seventh round of the Ghana Living Standards Survey (GLSS). We employ a multinomial endogenous switching regression (MESR) model that corrects for selection bias and endogeneity originating from both observed and unobserved heterogeneity. The results show that double shocks (pests and weeds) reduced the number of children attending school by 11% and increased children’s on-farm working hours by 0.75 h. Comparatively, the decline in the number of children attending school due to weed invasion (0.88) is higher than the decline due to pest invasion (0.43). Furthermore, weed invasion increases children’s on-farm working hours by 0.05 h while pest invasion reduces children’s on-farm working hours by 0.08 h. Increasing access to improved agricultural technologies bundled with credit and policies are critical to reducing the threats from ecological shocks and improving farmers’ welfare. To avert the decline in school attendance and children’s working hours requires training farmers to reduce the practice of continuous cropping and to embrace crop rotation and fallow to reduce the spread of pests and weeds.

Water turbidity affects the establishment of Neochetina eichhorniae (Warner) (Coleoptera: Curculionidae): Implications for biological control of water hyacinth

Water hyacinth is the target of nine biological control agents in South Africa including Neochetina eichhorniae (Warner) and Neochetina bruchi (Hustache) (Coleoptera: Curculionidae). These two weevils have also been released against water hyacinth in Rwanda, but failed to control the weed invasion, possibly due to high turbidity in the country's water bodies. This study therefore aimed to investigate the effect of water turbidity on the establishment and performance of N. eichhorniae in Rwanda. Turbidity levels were measured over two seasons in four Rwandan rivers and two lakes. The results were then used to benchmark laboratory trials to test the effect of turbidity on the weevils' development. Water hyacinth plants were maintained at four turbidity levels: Clear water (2 Nephelometric Turbidity Units (NTU): low (85 NTU), medium (600 NTU) and high (1500 NTU). Each treatment plant was inoculated with three N. eichhorniae larvae, while control plants were free of larvae. Plant growth was measured weekly for three months, while adult weevil emergence was recorded from the 56th day of the experiment. The number of adults emerging from the treatment plants grown in the clear water, low, medium and high turbidity levels were 24, 21, 12 and 0, respectively. Larval feeding was greater on plants growing in clear water and the low turbidity, compared to the medium and high turbidity treatments. These results indicate that N. eichhorniae may not establish or perform well in water bodies with high levels of turbidity, which in turn enhances the growth of water hyacinth, allowing compensatory growth for weevil feeding.

Recolonizing native wildlife facilitates exotic plant invasion into Singapore's rain forests

AbstractHalting biological invasions and rewilding extirpated native fauna are conservation interventions to bolster biodiversity, species interactions, and ecosystems. These actions are often considered separately and the potential for reintroduced wildlife to facilitate invasive plants has been largely overlooked. Here, we investigated the role of Singapore's recolonizing native wild pigs (Sus scrofa) in facilitating an invasive weed Miconia crenata into tropical rainforests, which are normally highly resistant to invasion. We conducted line‐transect surveys in 11 Singaporean rain forests and used generalized linear mixed models to consider the contribution of pigs' soil disturbances, human forest paths, and other environmental covariates, on the density of M. crenata. We found that M. crenata was more abundant at forest edges and invasion into forest interior was facilitated by pigs, paths, and canopy gaps, but that these effects were all additive, not synergistic (i.e., not multiplicative). These results highlight how modern invasions are driven by multiple disturbances as well as propagule pressure (e.g., urban birds dispersing seeds at forest edges where they establish in pig soil disturbances). Singapore's extensive native forest restoration efforts may have provided plentiful edge and secondary forests that are well suited to pigs and M. crenata, which in turn undermine the aims of fostering later‐successional native plant communities. To prevent negative externalities, we suggest that plant restoration and rewilding projects consider the potential role of wildlife in facilitating non‐native plants, and couple these actions with preliminary screening of unintended consequences and continued monitoring, as well as limiting human‐mediated weed invasion to minimize propagule sources.

Response of bacterial community characteristics in the rhizosphere soil of Stellera chamaejasme L. to its expansion on the Qinghai‐Tibet Plateau

AbstractQinghai‐Tibet Plateau is facing a serious environmental and ecological problem of Meadow degradation. Toxic weed invasion is a typical characteristic of grassland degradation. Soil microbial community composition is sensitive to environmental changes; however, the effects of poisonous weed expansion on soil bacterial communities are unclear. Here, we investigated the effects of Stellera chamaejasme L. expansion on the rhizosphere soil bacterial community structure and function using high‐throughput sequencing. The results showed that expansion of Stellera chamaejasme L. changed soil nitrogen(e.g., total nitrogen [TN, −39.02%], available nitrogen [AN, −32.95%]) and other soil nutrients. Redundancy analysis (RDA) and Variance partitioning analysis (VPA) showed that soil nutrients changed, leading to significant changes in the bacterial community structure. The expansion of Stellera chamaejasme L significantly reduced its rhizosphere bacterial alpha diversity, and the beta diversity had significant differences (p < 0.05). Principal coordinates analysis (PCoA) and analysis of similarity (ANOSIM) indicated that the expansion caused significant variations in the rhizosphere bacterial community (R = 0.7037, p < 0.01). The linear discriminant analysis (LDA) effect size (LEfSe) analysis identified 23 biomarkers, most of which were Proteobacteria, indicating that bacteria involved in soil nutrient cycling were better able to survive in the alpine grassland. The Biolog EcoPlate method was used to determine the soil microbial metabolic capacity in different S. chamaejasme expansions. The result showed that heavy expansion had higher carbon source usage ability and microbial diversity index values. Furthermore, it was also found that heavy expansion improved the usage rate of amino acid carbon sources. Tax4Fun prediction analysis further indicated that carbohydrate metabolism, amino acid metabolism, and membrane transport were central metabolic pathways of rhizosphere soil bacteria. Our study found that Stellera chamaejasme L. changed rhizosphere soil nutrient and bacterial community structure during expansion and helped it tolerate harsh conditions by enriching bacterial communities actively involved in carbon and nitrogen metabolism and promoting plant growth. These findings provided evidence to propose effective restoration measures for poisonous grassland degradation.

Functional trait-based restoration alters nutrient cycling and invasion rates in Hawaiian lowland wet forest.

Many degraded ecosystems have altered nutrient dynamics due to invaders' possessing a suite of traits that allow them to both outcompete native species and alter the environment. In ecosystems where invasive species have increased nutrient turnover rates, it can be difficult to reduce nutrient availability. This study examined whether a functional trait-based restoration approach involving the planting of species with conservative nutrient-use traits could slow rates of nutrient cycling and consequently reduce rates of invasion. We examined a functional trait restoration initiative in a heavily invaded lowland wet forest site in Hilo, Hawai'i. Native and introduced species were chosen to create four experimental hybrid forest communities, in comparison to the invaded forest, with a factorial design in which communities varied in rates of carbon turnover (slow or moderate [SLOW, MOD]), and in the relationship of species in trait space (redundant or complementary [RED, COMP]). After the first 5 years, we evaluated community-level outcomes related to nutrient cycling: carbon (C), nitrogen (N), and phosphorus (P) via litterfall, litter decomposition, and outplant productivity and rates of invasion. We found that (1) regardless of treatment, the experimental communities had low rates of nutrient cycling through litterfall relative to the invaded reference forest, (2) the MOD communities had greater nutrient release via litterfall than the SLOW communities, (3) introduced species had greater nutrient release than native species in the two MOD experimental communities, and (4) within treatments, there was a positive relationship between nutrient levels and outplant basal area, but outplant basal area was negatively associated with rates of invasion. The negative relationships among basal area and weed invasion, particularly for the two COMP treatments, suggest species existing in different parts of trait space may help confer some degree of invasion resistance. The diversification of trait space was facilitated by the use of introduced species, a new concept in Hawaiian forest management. Although challenges remain in endeavors to restore this heavily degraded ecosystem, this study provides evidence that functional trait-based restoration approaches using carefully crafted hybrid communities can reduce rates of nutrient cycling and invasion in order to reach management goals.

Equine Crofton Weed (Ageratina spp.) Pneumotoxicity: What Do We Know and What Do We Need to Know?

Crofton weed (Ageratina adenophora) is a global and highly invasive weed, with ingestion causing severe respiratory disease in horses, leading to irreversible and untreatable pulmonary fibrosis and oedema. While reports of equine pneumotoxicity remain common in Australia and New Zealand, equine pneumotoxicity may be underdiagnosed in other countries where Crofton weed is endemic but poorly differentiated. The pathogenesis of Crofton weed toxicity following ingestion has been well described in a number of different animal models, including rodents, rabbits, and goats. However, induced toxicity is organ-selective across different animal species, and these vastly differ from the pathogenesis described in horses, both clinically and after experimental exposure. Sources of variation may include species-specific susceptibility to different toxins present in the plant, different mechanistic processes of toxicity, and species differences in toxin biotransformation and bioactivation across different organs. Considering disease severity and Crofton weed's invasiveness globally, assessing published toxicological and exposure data is necessary to advance research, identify specific toxins for horses, and possible prophylactic and therapeutic strategies. This review presents an overview of the available literature on equine toxicity, parallels between toxicity in horses and other animal species, and important aspects to be included in the future research agenda.

The effectiveness of weed control in a threatened plant community: A grassland case study

Habitat loss due to altered land use has resulted in the fragmentation of remnant grasslands, resulting in an increase in the edge to area ratio and a subsequent rise in the risk of weed invasion. Restoration in threatened remnant grasslands focus on spot-spraying high threat herbaceous weeds with herbicides (i.e. weed control) as a dominant management action, but there is limited knowledge about the ecological outcomes of weed control effectiveness in these systems.In this study, we conducted a Before-After-Control-Impact analysis over three years using 32 linear grassland remnants to test whether weed control can improve grassland condition. Our predictions were that weed control would: (i) reduce the cover and health of pervasive exotic perennial grasses (i.e. target weeds), (ii) increase the cover of native plants by removing competition from target weeds, and (iii) not affect native plant richness as any recolonization will likely be from species already occurring in the area of sampling. We also predicted that weed control would shift the cover of ground layer attributes towards levels more appropriate for a grassland in good condition.Our results show that short-term weed control can be effective in reducing the cover and health of target weeds with minimal effects on native vascular plants. Changes in bare ground and litter cover following weed control were dynamic and complementary. A reduction in soil crust cover after two consecutive weed control treatments could lead to altered survival and recruitment dynamics of native grassland plants.Effective weed control requires actions that limit subsequent re-invasion by target weeds and promote a microenvironment suitable for native species to re-colonise. Our findings suggest a need to assess (i) if changes in ground layer cover post herbicide application affects native vegetation recruitment, and (ii) if other management activities, such as burning (in combination with, or independent of, weed control), are effective in controlling weeds while promoting better outcomes for ground layer cover (i.e. biological soil crust does not decrease) and native species (i.e. cover increases). If a strategy that eliminates target weeds while maintaining biological soil crust cover and increasing native cover can be identified, it will greatly improve the long-term restoration of these highly threatened grasslands.

Sown diversity effects on yield and resistance to weed invasion: Clues to improve mixture design under climatic change in the Mediterranean

With the aim to improve mixture design, particularly in regions vulnerable to climate change, we tested several forage communities following the biodiversity–ecosystem function (BEF) framework. We sowed monocultures and 4-species mixtures from a pool of 7 forage species in a sub-Mediterranean region (Eastern Pyrenees) and assessed the diversity effects on yield and resistance to weed invasion. The tested species included two grasses and five legumes with contrasting temporal patterns and different climatic amplitudes. The communities differed in their specific composition (mixture types) and the relative abundance of the components, following a simplex design, which allowed us to estimate separately the two components of the diversity effect: the individual species effects and that due to species interactions. Whereas monocultures performed in a highly variable way within and across harvests, both in relation to yield and weed suppression, mixture variability was narrower. Both functions increased in mixtures (with significant interaction effects between 24% and 57% for yield and 13% and 96% for weed suppression), especially in those mixtures including Mediterranean species, which showed the highest diversity effects that persisted over the three experimental years. Extreme climatic events during the experimental period might have affected not only the species’ individual performances but also the strength of species interactions. Both components of diversity, identities and interactions, were key in maintaining high performances. We conclude that, under the current climate change scenario, it is important to include species in mixtures that increase resistance or resilience not only at the species level but also at the community level, through enhanced interaction effects.

Different Weed Management Techniques in Maize (Zea mays L.): A Review

Farmers are subjected to yield loss due to different reasons including weed invasion. As weed management is a major approach different methods are incorporated for their management like cultural, mechanical and chemical, etc. Different strategies are required for eradication as cultural methods can’t be used in large area as application of herbicide or tillage methods are found effective in such conditions. Use of compatible herbicides is necessary as they have different way of approach to weeds as different weed species are observed on field. From this review it is concluded that cultural as well as chemical means both are effective when used in a significant manner and application is done according to land area taken into consideration.

Grazing Intensity and Seasonality Manipulate Invasive Annual Grasses and Native Vegetation

Simultaneous desires for greater livestock production and reduced purchased feed inputs are further complicated by potential for rangeland degradation and weed invasion. Grazing management that emphasizes greater use of dormant rangeland forages may provide solutions. We tested grazing season (summer or fall) and intensity (moderate or heavy) combination effects on plant community composition and productivity to determine whether rangelands can sustain heavy dormant-season use without reducing native perennials. Treatment combinations were randomly assigned to 20, 60 × 30 m plots that were grazed from 2013 through 2017. Total current-yr biomass was greatest with moderate fall grazing (1 350 ± 41 kg ha−1) and similar among heavy fall, heavy summer, and moderate summer grazing (1 206 ± 41 kg ha−1). Heavy summer grazing had the lightest native species standing crop. Heavy summer grazing reduced perennial C3 grass standing crop 22%, primarily through effects on needle-and-thread (Hesperostipa comata [Trin. & Rupr.] Barkworth) and threadleaf sedge (Carex filifolia Nutt.). Moderate dormant fall grazing increased perennial C3 grass standing crop 15% but also increased the invasive annual, Japanese brome (Bromus japonicus Thunb.). Heavy dormant fall grazing effects did not differ from that of moderate summer grazing for perennial C3 grass or total native species standing crop, but heavy fall grazing reduced cheatgrass (Bromus tectorum L.) 51%. Where B. japonicus and B. tectorum co-occur, moderate growing season grazing combined with heavy dormant fall grazing may be needed to affect both species. Diversity and native species standing crop were similar between heavy fall and moderate summer grazing, but heavy fall grazing caused the least non-native species standing crop. Heavy fall use is recommended as potential treatment to be rotated among pastures over time or focused on pastures that could benefit from effects observed. Effects likely vary with differences in climate or species composition.