Integrated Weed Management Research Articles

SERVICES OFFERED BY THE RBKS AND TRAINING NEEDS OF VILLAGE AGRICULTURAL ASSISTANTS IN GUNTUR DISTRICT

The attempt was made to analyse the awareness and utility of RBK services by the farmers and training needs of Village Agricultural Assistants (VAAs) in Guntur district. Hundred farmers from 10 subdivisions and 165 VAAs from 55 mandals were selected asthe respondents. Majority of the farmers were aware of distribution of quality fertilizers (88.00%), e-crop booking (86.00%), soil & water testing facility (78.00%), free crop insurance/ animal insurance (75.00%), provision of quality seed (green manure/ crop seed/fodder seed/concentrate feed) (73.00%), distribution of quality pesticides (60.00%) and provision of need based information to farmers on crop healthmanagement (57.00%). With respect to utility, only few services are utilised by the farmers’ viz., e crop booking (82.00%), free crop insurance / animal insurance (59.00%) and distribution of quality fertilizers (58.00%). Majority of the Village Agricultural Assistants expressed that Integrated Disease Management (87.27 TNI & Rank I), Integrated Pest management (83.64TNI &Rank II), new varieties (81.41TNI & Rank III),Micro nutrient management (80.80TNI & Rank IV), Integrated weed management (80.20 TNI & Rank V) are the major areas of training needed by them. Major constraints expressed by VAAs are inability to meet the demands of farmers with respect to providing all of them with subsidies, inability to maintain sufficient fertilizers, pesticides and otherstocks as required by farmers and Heavy work load.

Effect of Integrated Weed Management Practices on Microbial Population in Soil, Yield and Economics in Wet Direct Seeded Rice

An experiment had been conducted at the Agronomy Farm, Indira Gandhi Krishi Vishwavidyalaya, Raipur, (C.G.) in the kharif season of 2019, to determine the effects of integrated weed management practices on microbial population in soil, yield and economics in wet direct seeded rice. Pre-emergence herbicides (Oxadiargyl and Pretilachlor) were followed by post-emergence herbicide (Bispyribac-Na), mechanical and manual weeding. Plots treated with oxadiargyl performed better than pretilachlor. When Oxadiargyl was integrated with Hand Weeding (HW) at 35 days after sowing (DAS) gave results which were better than twice HW plot (T10). Oxadiargyl @ 70g/ha at 7-11 DAS fb HW at 30-35 DAS (T4) proved to be superior over all the treatments when yield and economics of wet direct seeded rice was concerned and was statistically at par with twice HW plot (T10) and oxadiargyl @ 70 g/ha at 7-11 DAS fb bispyribac-Na @ 25 g/ha at 30-35 DAS (T2). The unsprayed and two-hand weeding treatments had much lower levels of fungi, actinobacteria, and bacteria than the other weed control methods. The herbicidal treatments had much higher microbial populations at all stages of observation.

Preliminary report on the comparative weed suppressibility of Bangladeshi Wheat varieties

A key and ecologically sound strategy for integrated weed management is the use of varieties of weed-competitive crops. Utilizing wheat cultivars that are weed-competitive can lessen weed pressure and inordinate herbicide usage in wheat fields by a substantial amount. To assess the weed suppressibility of Bangladeshi wheat varieties, a field test was carried out in 2018 throughout the winter season at the Agronomy Field Laboratory, Bangladesh Agricultural University, Bangladesh. Tests on a total of 18 selected Bangladeshi wheat cultivars were conducted in both “weedy” and “weed-free” environments. Additionally, weed monoculture plots (without wheat) were kept. The experiment was replicated three times using a randomized complete block design (RCBD). The results demonstrated that wheat varieties' weed interference and production capabilities differed greatly. BARI Gom 22 permitted the most weed growth (35 m−2), whereas BARI Gom 23 allowed the least (15 m−2) at 60 DAS among the wheat types under study. Grain yield ranged between 4.42 t ha−1 (BARI Gom 20) and 5.45 t ha−1 (BARI Gom 26) in weed-free settings, whereas it fluctuated from 2.48 t ha−1 (BARI Gom 21) to 3.93 t ha−1(BARI Gom 33) in weedy condition. The extent of the relative yield loss brought on by weeds ranged from 24 to 53%, with BARI Gom 33 suffering the least and Binagom-1 suffering the most. The weed competitive index varied from 0.48 to 1.47 for the examined wheat types. Among the cultivars, Binagom-1 had the lowest WCI and BARI Gom 29 had the highest. Although BARI Gom 33 was the best yielder in weedy condition and had the lowest relative yield loss, its interference against weed was moderate. Relative to the other varieties under consideration, comparatively BARI Gom 33 was the best in terms of yield and weed interference, but it is also advocated that breeders should continually focus on developing a variety that has both excellent producing potential and robust weed suppression.

Integrated management of Corn Marigold (Glebionis segetum) in Tef Field at Western and Southwestern Shewa zones in Ethiopia

Background: Corn marigold is a serious weed species of agricultural crops in many parts of Ethiopia. However, there is a lack of information on its management in tef fields in the country. Therefore, the current work was designed with the objectives of evaluating integrated management of the weed and determining the most economical integrated weed management options in tef fields. Methods: The field experiment was conducted at naturally Corn marigold infested fields of Chaliya and Waliso districts of Western and Southwestern Ethiopia, respectively during 2020 to 2021 cropping seasons. Results: Different Corn marigold management practices exhibited different responses to different parameters of the target weed and the test crop differently. Application of Pallas 45 OD at a rate of 0.40 l ha-1 supplemented with once-hand weeding and QuelexTM 200 WG sprayed at a rate of 50 g ha-1 supplemented with once-hand weeding increased grain yield by about 70 and 50%, respectively, over weedy check. The marginal revenue and benefit-cost ratio inflicted from the marketing of goods for every one of integrated management of Corn marigold increased by about 42–110 and 32–89%, respectively as compared to a weedy check. Conclusions: The present study revealed the role of integrated management of Corn marigold in improving tef production and productivity by combating the weed. Future research should be directed towards scaling up and popularizing these technologies among end users.

Overwintering Camelina and Canola/Rapeseed Show Promise for Improving Integrated Weed Management Approaches in the Upper Midwestern U.S.

Winter oilseed cash cover crops are gaining popularity in integrated weed management programs for suppressing weeds. A study was conducted at two field sites (Fargo, North Dakota, and Morris, Minnesota) to determine the freezing tolerance and weed-suppressing traits of winter canola/rapeseed (Brassica napus L.) and winter camelina [Camelina sativa (L.) Crantz] in the Upper Midwestern USA. The top 10 freezing tolerant accessions from a phenotyped population of winter canola/rapeseed were bulked and planted at both locations along with winter camelina (cv. Joelle) as a check. To phenotype our entire winter B. napus population (621 accessions) for freezing tolerance, seeds were also bulked and planted at both locations. All B. napus and camelina were no-till seeded at Fargo and Morris at two planting dates, late August (PD1) and mid-September (PD2) 2019. Data for winter survival of oilseed crops (plants m-2) and their corresponding weed suppression (plants m-2 and dry matter m-2) were collected on two sampling dates (SD) in May and June 2020. Crop and SD were significant (p < 0.05) for crop plant density at both locations, and PD in Fargo and crop x PD interaction in Morris were significant for weed dry matter. At Morris and Fargo, PD1 produced greater winter B. napus survival (28% and 5%, respectively) and PD2 produced higher camelina survival (79% and 72%, respectively). Based on coefficient of determination (r2), ~50% of weed density was explained by camelina density, whereas ≤20% was explained by B. napus density at both locations. Camelina from PD2 suppressed weed dry matter by >90% of fallow at both locations, whereas weed dry matter in B. napus was not significantly different from fallow at either PD. Genotyping of overwintering canola/rapeseed under field conditions identified nine accessions that survived at both locations, which also had excellent freezing tolerance under controlled conditions. These accessions are good candidates for improving freezing tolerance in commercial canola cultivars.

Delayed cover-crop termination and reduced herbicide inputs produce trade-offs in soybean phase of US Northeast forage-grain rotation

AbstractRegion- and system-specific research is needed to understand the viability of delayed cover-crop termination (i.e., planting green) as an integrated weed management (IWM) tactic in no-till soybean. In a 3-yr field experiment, we evaluated the potential for planting green to facilitate elimination of soil-applied, preemergence residual herbicides within a soybean phase of a 6-yr grain–forage cropping systems experiment in Pennsylvania. This IWM tactic was contrasted with a Standard treatment, which included 14 to 21 d pre-plant termination of cereal rye and a two-pass herbicide program with preemergence herbicides. A 63% increase in cereal rye biomass production was observed within the IWM treatment in 2019, but only a 22% and 33% increase in 2020 and 2021, respectively. In 2020, significantly lower volumetric water content (%VWC) was observed within the IWM treatment in dates closest to planting and greater %VWC at multiple dates in June and July compared to the Standard treatment. No differences occurred in soybean populations, but soybean biomass at the V4 growth stage was reduced in the Standard treatment compared to the IWM treatment, which we attribute to injury from preemergence applications. The Standard treatment resulted in greater soybean yield (2,590 kg ha–1) than the IWM treatment (1,870 kg ha–1) in 2020, but yields were similar in other years. The IWM treatment resulted in 58% fewer herbicide inputs, as measured by the number of active ingredients applied, compared to the Standard over the 3-yr study. Yet, peak weed biomass did not differ between treatments. However, the IWM treatment resulted in greater total horseweed density and the number of horseweed plants that exceeded recommended size-based height thresholds (10 cm) compared to the Standard treatment just prior to postemergence applications (35–42 d after planting) in 2020 and 2021, underscoring the importance of integrating surface mulch residues with effective herbicide sites of action.

Ecological, phytosanitary, and agronomic aspects of target weeds for biological control studies in Antioquia, Colombia

Biological control as part of integrated weed management represents an emerging and promising method to minimize the use and impact of herbicides on the environment. The objective of this research was to determine the ecological, phytosanitary, and agronomic status of weeds associated with crops in Antioquia, Colombia, and their potential to be chosen as candidates for biological control studies using pathogenic fungi. The research was carried out through a sampling of weeds in 35 agricultural farms, distributed in 11 municipalities and 10 different crops, on which population ecological variables such as frequency and dominance were evaluated; phytosanitary variables such as incidence and severity of foliar fungal symptoms; as well as some biological and anthropogenic aspects of these, through interviews with the farmers of each farm. The integration of these variables was proposed as an indicator to order and classify the plants according to their greater suitability to be subjected to biocontrol studies. A diversity of 75 weed species was found, with the Poaceae and Asteraceae families standing out, which together represented 43% of the population. 76% of this population presented disease symptoms, presumably of fungal origin, with the severity of up to 10% of the affected leaf area. In 22% of the species agronomic management difficulties greater than 50% were detected on a scale of 1 to 10. We indicate the following twelve weed species as candidates for future biological control studies through phytopathogenic fungi: Rumex crispus L., Digitaria horizontalis (Willd), Persicaria nepalensis (Meisn.) Miyabe, Thunbergia alata Bojer ex Sims, Melinis minutiflora Beauv., Paspalum paniculatum L., Pennisetum clandestinum Hochst. ex Chiov., Pteridium aquilinum (L.) Kunth, Sonchus oleraceus L., Erigeron bonariensis L., Bidens pilosa L., and Artemisia absinthium L. This is the first report of its kind in Colombia.

Growth analysis and yield evaluation under tillage and weed management practices in maize-wheat cropping system

Integrated weed management strategies combine tillage systems and weed control strategies. Conservation agriculture (CA) and sustainable intensification cropping systems are potential sources of improved growth and overall productivity. This study evaluated tillage and weed management strategies effects on crop growth parameters and biological yields in maize-wheat cropping system in North Western Himalayan region. Different tillage (five) and weed management practices (three) were evaluated from 2018 to 2020 on growth indices and yield with fifteen treatments. Conservation agriculture (CA) based production system (ZT, zero tillage; crop rotation and intensification; residue management i.e. ZTR-ZTR) had higher crop dry matter accumulation (DMA), relative growth rate (RGR), crop growth rate (RGR) and biological yield of maize (28698 kg/ha) and wheat crops (18750 kg/ha). The zero tillage in maize and wheat (ZT-ZT) resulted in lowest maize (24677 kg/ha) and wheat biological yield (14009 kg/ha. Among weed management treatments, application of recommended herbicides in maize and wheat crop (H-H) resulted in higher crop DMA and biological yield of maize (27652 kg/ha) and wheat crop (19540 kg/ha). Therefore, for North Western Himalayan conditions, ZTR+H-ZTR+H (Conservation tillage combined with herbicide application in maize and wheat) is superior to other combinations for growth and yield.

Morphological responses of maize hybrids under competition with hairy beggarticks

ABSTRACT The study of competitive interactions between crops and weeds can be an important tool in integrated weed management. The objective of this work was to evaluate the competitive ability of maize hybrids in the presence of hairy beggarticks, testing different proportions of plants in the associations. For maize hybrids (Dekalb 230 PRO3, Pioneer 30F53 VYH, Brevant 2B433 PW, and Syngenta 505 VIP3) and for hairy beggarticks, the final density was 20 individuals pot-1, which was determined in preliminary experiments. Experiments were carried out on a substitutive series, on different combinations of the species, varying the relative proportions (100:0, 75:25, 50:50, 25:75, and 0:100%). The analysis of species competitiveness was performed using diagrams applied to the substitutive experiments and relative competitiveness indices. The maize hybrids showed less loss when reducing the morphological variables of the hairy beggarticks and demonstrated superiority in competitive ability in relation to the weed. Competition occurred between maize hybrids in the presence of hairy beggarticks, being negatively affected, regardless of the proportion of plants, causing reductions in plant height, stem diameter, leaf area, and dry mass. An average reduction of 10% and 86% of the MS of maize hybrids and weed was observed, respectively, when comparing the absence of competition with any associated densities, intraspecific competition being more harmful than interspecific. Maize hybrids and hairy beggarticks compete for the same environmental resources, with the crop being more competitive than the competitor.

Effect of osmotic potential and temperature on germination of kochia (Bassia scoparia) populations from the U.S. Great Plains

AbstractDevelopment of integrated weed management strategies requires knowledge of weed emergence timing and patterns, which are regulated primarily by water and thermal requirements for seed germination. Laboratory experiments were conducted in fall 2017 to fall 2018 to quantify the effect of osmotic potential and temperature on germination of 44 kochia [Bassia scoparia (L.) A.J. Scott] populations under controlled conditions. Bassia scoparia populations were collected in fall 2016 from northern (near Huntley, MT, and Powell, WY) and southern (near Lingle, WY, and Scottsbluff, NE) regions of the U.S. Great Plains. Ten osmotic potentials from 0 to −2.1 MPa and eight constant temperatures from 4 to 26 C were evaluated. Response of B. scoparia populations to osmotic potential did not differ between the northern and southern regions. At an osmotic potential of 0 MPa, all B. scoparia populations had greater than 98% germination, and the time to achieve 50% germination (t50) was less than 1 d. At −1.6 MPa, 25% of seeds of all B. scoparia populations germinated. Osmotic potentials of −0.85 and −1.9 MPa reduced B. scoparia germination by 10% and 90%, respectively. Regardless of temperature regime, all populations exhibited greater than 88% germination. The germination rate was highest at temperatures between 15 to 26 C and did not differ between populations from northern versus southern regions. At this temperature range, all populations had a t50 of less than 1 d. However, at 4 C, B. scoparia populations from the northern region had a higher germination rate (5 h) and cumulative germination (7%) than populations from the southern region. Overall, these results indicate a wide range of optimum temperatures and osmotic potential requirements for B. scoparia germination.

Evaluation of finger weeder safety and efficacy for intra‐row weed removal in irrigated field crops

AbstractIncreased demand for pesticide‐free food and the development of herbicide‐resistant weed populations have created a need for non‐chemical weed‐control tools. A candidate mechanical tool for controlling weeds in the seeding line (intra‐row zone) is the finger weeder. This study thus aimed to evaluate the safety and weed‐control efficacy of the finger weeder in various irrigated field crops. Eight field trials were conducted in processing tomato, sweet corn, sunflower, cotton, and beetroot over 2 years. The finger weeder treatments were applied as the sole weed‐control method (single or double treatments) and in combination with herbicides. A mini meta‐analysis was used to evaluate the overall effect of the finger weeder treatments on crop stand and yield and on weed control efficacy. Weed density in the control not treated with herbicides nor a finger weeder ranged between 2 and 62 weeds m−2. The finger weeder treatments resulted in a significant reduction in weed density, which ranged between 40% and 90%. The weed density following the double finger weeder treatment was not significantly different from that for the conventional herbicide‐based treatment (p = 0.32) and could therefore be considered as an effective environmentally friendly alternative. Furthermore, a single FW treatment integrated with herbicide application gave better weed control than the conventional herbicide treatment (p = 0.04). This treatment was safe for the crops with no significant stand (p = 0.19) or yield (p = 0.29) reductions compared to commercial treatment. The results of this study demonstrate the promise of the finger weeder as an effective tool within integrated weed management systems for conventional agro‐systems. The tool offers a rational weed‐control solution for sustainable systems under irrigation.

Seed Germination of Three Milk Thistle (Silybum marianum (L.) Gaertn.) Populations of Greek Origin: Temperature, Duration, and Storage Conditions Effects

Milk thistle besides being a highly competitive weed is cultivated as a medicinal plant, and the seeds of which have been clinically utilized in several disorders caused in liver. The present study aims to evaluate the effect of duration and storage conditions, population, and temperature on seed germination. The experiment was conducted in Petri dishes with three replications and three factors: (a) wild populations of milk thistle (Palaionterveno, Mesopotamia, and Spata) originating from Greece, (b) duration and storage conditions (5 months at room temperature, 17 months at room temperature, and 29 months in the freezer at -18 °C), and (c) temperature (5 °C, 10 °C, 15 °C, 20 °C, 25 °C, and 30 °C). All three factors significantly affected germination percentage (GP), mean germination time (MGT), germination index (GI), radicle length (RL), and hypocotyl length (HL) and significant interactions among the treatments were noted. In specific, no seed germination was recorded at 5 °C, while the populations showed higher GP and GI at 20 °C and 25 °C after 5 months of storage. Prolonged storage negatively affected seed germination although, cold storage mitigated this effect. Moreover, higher temperatures reduced MGT and increased RL and HL with the populations reacting differently in storage and temperature regimes. The results of this study should be taken into consideration when proposing the appropriate sowing date and storage conditions of the seeds used as propagation material for crop establishment. Moreover, the effects of low temperatures such as 5 °C or 10 °C on seed germination as well as the high decline rate in germination percentage over time could be utilized in the design of integrated weed management systems thereby indicating the importance of the sowing time and the suitable crop rotation system to weed control.

Integrated weed management strategies in a long-term crop rotation system

Background Diversified crop systems provide several advantages for crop production and the agricultural ecosystem. In contrast, growing the same crop for consecutive years increases weeds, insects, and diseases issues, adding further cost to crop production owing to their management. Objective The objective was to evaluate the effects of six different winter cover crops and compare the impacts of a diversified rotation system in contrast to the succession system, combined with three different post-emergence herbicide management looking up to soybean [...]

First report of a wide distribution of glyphosate-resistant compact brome (Bromus madritensis) in the Iberian Peninsula: confirmation and field management

AbstractGlyphosate resistance is spreading in Spain and Portugal due to excessive herbicide use, in both annual and perennial crops. Compact brome (Bromus madritensis L.) is increasing in frequency in these different cropping systems when under conservation agriculture, particularly when glyphosate fails to control it. Fourteen populations from different areas in the Iberian Peninsula were confirmed as being B. madritensis using simple sequence repeat markers and clearly separated from the closely related species red brome (Bromus rubens L.) and ripgut brome (Bromus diandrus Roth). Six B. madritensis populations were classified as resistant, according to both their shikimic acid accumulation levels and their resistance factors based on LD50 or GR50 (values between 4 and 8). Populations with higher resistance factors also showed lower shikimic acid concentrations. Moreover, these resistant populations were able to survive the minimum registered dose for glyphosate in Spain in perennial crops (1,080 g ae ha−1, five populations) or in arable crops before seeding for annual weeds (540 g ae ha−1, one population), under both greenhouse and field conditions. The trials carried out in a glyphosate-resistant field during 2 consecutive years showed that acceptable control (≥90%) was only consistently achieved 90 d after application for preemergence treatment with flazasulfuron in a tank mix with glyphosate, while control with postemergence treatments, such as propaquizafop plus glyphosate, was below 80%. This research describes the first herbicide-resistance report for the weed species B. madritensis, confirming the presence of glyphosate-resistant populations mainly in perennial cropping systems but also in winter cereals from Spain. Due to the limited chemical tools to manage these populations, there is an urgent need for farmers to implement integrated weed management strategies.

Impacts of two years of autumn cover crops in northwestern Washington on winter annual weed populations

AbstractCover cropping is a suggested soil conservation practice widely investigated in cropping systems. Cover crops suppress weeds and often are part of an integrated weed management plan that could lead to reduced herbicide use and possibly reduce the weed seedbank. Winter brassica cover crops are popular in the eastern Washington potato (Solanum tuberosum L.) production region, but in western Washington, the production of brassica seed crops presents disease issues along with the risk of cross-pollination, which limits the use of brassica cover crops. Research for this article was conducted in two trials from 2018 to 2020 and 2019 to 2021in Mount Vernon, Washington, to identify winter cover crops compatible with regional restrictions and climatic challenges in western Washington cropping systems. Treatments including a no-cover control, eight single species (including brassicas, grasses, and legumes), and a grass–legume mixture were investigated. Cover crop and weed biomass production were measured, and percent ground cover for cover crops and weeds by species was estimated. Cover crop biomass and weed suppression varied by year due to variable environments, but annual ryegrass (Lolium multiflorum Lam.) and the mixture were most consistent in producing large amounts of biomass and reducing weed biomass and cover in all years. The variability of percent weed cover response to environment was ameliorated when weed cover was normalized within each year’s control.

Germination responses of vipergrass (Dinebra retroflexa) to environmental factors and herbicide options for its control

AbstractVipergrass [Dinebra retroflexa (Vahl) Panzer] is an annual weed of the Poaceae family distributed in several parts of Australia, Asia, and Europe. Very limited information is available on its germination response to different environmental conditions. Knowledge of its seed ecology and biology could help in formulating better weed management decisions. Experiments were conducted to study the effect of alternating temperatures, light conditions, salt stress, water stress, seed burial depths, and wheat residue amounts on the germination or emergence of D. retroflexa. Also, different pre- and postemergence herbicides were evaluated to control D. retroflexa. The highest germination (98%) was recorded at 30/20 C followed by 35/25 C (95%). Light was required for the germination of D. retroflexa. Germination decreased with an increase in sodium chloride (NaCl) concentrations. Even at 80 mM NaCl, 81% of seeds germinated, indicating D. retroflexa’s high salt tolerance. Seed germination gradually decreased with an increase in water stress, and no germination was recorded at −0.8 MPa osmotic potential. The emergence of D. retroflexa decreased with an increase in seed burial depths. The highest germination (83%) was recorded for surface-sown seeds, and emergence was reduced to 0 at a burial depth of 2 cm. Seedling emergence decreased from 82% to 2% when the crop residue load was increased from 0 to 800 kg ha−1. Applications of preemergence herbicides (at field rates), such as diuron, isoxaflutole, pendimethalin, pyroxasulfone, S-metolachlor, terbuthylazine, and triallate, and postemergence herbicides, such as clethodim, haloxyfop-methyl, glufosinate, glyphosate, imazamox plus imazapyr (a commercial mixture), and paraquat, resulted in complete control (100%) of D. retroflexa. Knowledge gained from this study will help us to understand the potential spread of D. retroflexa to other areas and to formulate integrated weed management strategies for its effective control.

The Potential of Cover Crops for Weed Management: A Sole Tool or Component of an Integrated Weed Management System?

Cover crops are an important component of integrated weed management programs in annual and perennial cropping systems because of their weed suppressive abilities. They influence weed populations using different mechanisms of plant interaction which can be facilitative or suppressive. However, the question often arises if cover crops can be solely relied upon for weed management or not. In this review we have tried to provide examples to answer this question. The most common methods of weed suppression by an actively growing cover crop include competition for limited plant growth resources that result in reduced weed biomass, seed production, and hence reductions in the addition of seeds to the soil seedbank. Cover crop mulches suppress weeds by reducing weed seedling emergence through allelopathic effects or physical effects of shading. However, there is a great degree of variability in the success or failure of cover crops in suppressing weeds that are influenced by the cover crop species, time of planting, cover crop densities and biomass, time of cover crop termination, the cash crop following in the rotation, and the season associated with several climatic variables. Several studies demonstrated that planting date was important to achieve maximum cover crop biomass, and a mixture of cover crop species was better than single cover crop species to achieve good weed suppression. Most of the studies that have demonstrated success in weed suppression have only shown partial success and not total success in weed suppression. Therefore, cover crops as a sole tool may not be sufficient to reduce weeds and need to be supplemented with other weed management tools. Nevertheless, cover crops are an important component of the toolbox for integrated weed management.

Integrated weed management strategies for the depletion of multiple herbicide-resistant waterhemp (Amaranthus tuberculatus) seed in the soil seedbank

AbstractThe development of an integrated weed management (IWM) strategy for control of multiple herbicide-resistant (MHR) waterhemp can provide field crop producers with a strategy to deplete the number of waterhemp seeds in the soil seedbank. Field experiments were established on two commercial farms in Ontario, Canada, with MHR waterhemp in 2017. The number of waterhemp seeds in the seedbank at the Cottam and Walpole Island sites prior to establishing the experiments was 413 and 40 million seeds ha−1, respectively. The goal of this 9-yr study is to document the depletion in the number of waterhemp seeds in the seedbank after Years 3, 6, and 9 (spring 2020, 2023, and 2026) and to identify management practices that can reduce the number of waterhemp seeds by 95% or more. Relative to the number of seeds in the soil seedbank when the experiment was initiated, at the Cottam site after 3 yr of this experiment, in the “control” treatment (continuous soybean seeded in rows spaced 75 apart, and sprayed with glyphosate) there was a numeric 31% increase in the number of waterhemp seeds in the seedbank; in contrast, in the three-crop rotation of corn/soybean/winter wheat (with or without a cover crop after winter wheat harvest), soybean seeded in rows spaced 37.5 cm apart, with herbicide applications using a total of eight different herbicide modes of action resulted in a 65% to 66% decrease in the number of waterhemp seeds in the soil seedbank. At the Walpole Island site after 3 yr of this experiment, the number of waterhemp seeds in the seedbank was not affected by the IWM programs evaluated. Results indicate that a diversified integrated waterhemp management program dramatically decreased the number of waterhemp seeds in the seedbank at one of two sites.

Herbicide Use in the Era of Farm to Fork: Strengths, Weaknesses, and Future Implications.

Climate change mitigation is a major concern of the European Union (EU). In 2019, the EU presented the European Green Deal (EGD), a new environmental strategy that aimed to neutralize climate change by 2050. Within its policy areas, the EGD included the Farm to Fork (F2F) Strategy that aims to reduce pesticide use by 50%, by 2030. This reduction was proposed due to the supposed negative effects of pesticides on the environment and its biota. Among the different pesticide groups (herbicides, fungicides, insecticides, etc.) though, herbicides are perhaps the hardest to reduce. This review aimed to shed light to any factors that might hinder the reduction of herbicide use; thus, the implementation of the Farm to Fork Strategy underlines some of its weaknesses and highlights key points of a viable herbicide reduction-related policy framework. The literature suggests that integrated weed management (IWM) consists perhaps the most suitable approach for the reduction of herbicides in the EU. Even though it is too soon to conclusively assess F2F, its success is not impossible.

Herbicide Resistance Is Increasing in Spain: Concomitant Management and Prevention.

Herbicide-resistant weeds currently challenge sustainable food production in almost all cropping systems in Europe. Herbicide resistance is increasing, and some European countries are among the most affected globally, such as Spain and France. This situation is worsening not only due to herbicide use restrictions but also due to climate change, rendering Mediterranean countries such as Spain particularly susceptible. Therefore, focus should be aimed at preventive measures, which include those not only based on integrated weed management strategies but also based on a very good knowledge of the biology and ecology of each weed species. The main objective of this review is to provide an overview of potential future herbicide-resistant cases that can evolve in the near future in Europe. We use Spain as the case study, as it is the most affected country in Europe and because it is at risk due to global warming. For different resistant cases detailed on a crop basis, adequate prevention and management measures will be provided in order to avoid resistance evolution relative to the sites of action that are most likely to generate resistant biotypes due to expected high selection pressures.