The loss of weed biodiversity in agricultural fields is a global issue that needs to be counteracted to preserve their supported ecosystem services and food webs. Many short-term efforts are undertaken to conserve weed species, especially already endangered ones, but several years after expiration, eventually result in species-poor communities. Understanding drivers of community composition is key to prevent biodiversity loss. To understand the factors that shape weed communities and influence weed diversity and endangered weed species, we monitored conventional and organic cereal fields in two regions of southwestern Germany. A redundancy analysis was performed on vegetation recordings and data from a farmer survey. Crop species, herbicide use, farming system, nitrogen, and light availability had the strongest impact on weed diversity. The weed communities were dominated by Alopecurus myosuroides, Galium aparine, Viola arvensis, Polygonum convolvulus, and Veronica persica, and were mainly shaped by crop species, tillage, location in the field, and timing of herbicide application. Bromus grossus and Bromus secalinus, two endangered weed species, survived in conventional field margins as a result of the use of herbicides with gaps for Bromus species. Conservation efforts are not restricted to organic farming and should consider the major drivers of weed communities. Precision farming techniques are available to create networks of habitats for endangered and common weed species and subsequently increase agro-biodiversity per se. Full article

The utilization of an effective stubble management practice can reduce weed infestation before and in the following main crop. Different strategies can be used, incorporating mechanical, biological, and chemical measures. This study aims at estimating the effects of cover crop (CC) mixtures, various stubble tillage methods, and glyphosate treatments on black-grass, volunteer wheat and total weed infestation. Two experimental trials were conducted in Southwestern Germany including seven weed management treatments: flat soil tillage, deep soil tillage, ploughing, single glyphosate application, dual glyphosate application, and a CC mixture sown in a mulch-till and no-till system. An untreated control treatment without any processing was also included. Weed species were identified and counted once per month from October until December. The CC mixtures achieved a black-grass control efficacy of up to 100%, whereas stubble tillage and the single glyphosate treatment did not reduce the black-grass population, on the contrary it induced an increase of black-grass plants. The dual glyphosate application showed, similar to the CC treatments, best results for total weed and volunteer wheat reduction. The results demonstrated, that well developed CCs have a great ability for weed control and highlight that soil conservation systems do not have to rely on chemical weed control practices. Full article

Resistance to herbicides in Italian ryegrass (Lolium perenne L. ssp. multiflorum (Lam.) Husnot) is an economically important herbicide-resistance issue in world agriculture. Diclofop-resistant ryegrass is the number one weed problem in Arkansas wheat. Field studies were conducted from 2006 through 2008 at Bredlow corner and Fayetteville, Arkansas, USA to determine the effect of herbicide programs consisting of pinoxaden (Axial) alone or in mixtures with preemergence and postemergence herbicides, along with tillage systems, for managing diclofop-resistant Italian ryegrass. Italian ryegrass control, wheat injury, and grain yield were evaluated. A single treatment with pinoxaden alone resulted in 58% ryegrass control and 1488 kg ha⁻¹ grain yield. The best treatment was metribuzin followed by mesosulfuron, which resulted in 2793 kg grain yield ha⁻¹, a 47% increase compared to pinoxaden alone. In Fayetteville (2006–2007 and 2007–2008), the best treatment was two applications of metribuzin, which yielded about 3700 kg grain ha⁻¹. A single application of pinoxaden resulted in 40% loss of grain yield compared to a single application of flufenacet + metribuzin and almost 50% yield loss compared to sequential application of metribuzin. Yield loss was attributed due to insufficient control of Italian ryegrass. The effect of tillage on Italian ryegrass was inconsistent between years and treatments. In the first year, for example, tillage × herbicide treatments did not differ. In the second and third year, control of Italian ryegrass was better in no-till than in conventional till in both locations. In conclusion, pinoxaden alone could not control diclofop-resistant Italian ryegrass sufficiently. Other herbicide modes of action need to be added to the management program of diclofop-resistant Italian ryegrass, especially one with residual activity such as metribuzin. Full article

Sensor-based weed mapping in arable fields is a key element for site-specific herbicide management strategies. In this study, we investigated the generation of application maps based on Unmanned Aerial Vehicle imagery and present a site-specific herbicide application using those maps. Field trials for site-specific herbicide applications and multi-temporal image flights were carried out in maize (Zea mays L.) and sugar beet (Beta vulgaris L.) in southern Germany. Real-time kinematic Global Positioning System precision planting information provided the input for determining plant rows in the geocoded aerial images. Vegetation indices combined with generated plant height data were used to detect the patches containing creeping thistle (Cirsium arvense (L.) Scop.) and curled dock (Rumex crispus L.). The computed weed maps showed the presence or absence of the aforementioned weeds on the fields, clustered to 9 m × 9 m grid cells. The precision of the correct classification varied from 96% in maize to 80% in the last sugar beet treatment. The computational underestimation of manual mapped C. arvense and R. cripus patches varied from 1% to 10% respectively. Overall, the developed algorithm performed well, identifying tall perennial weeds for the computation of large-scale herbicide application maps. Full article

Two of the most troublesome weeds in soybean, cotton, and corn in cropping systems of mid-south United States (US) are Senna obtusifolia and Xanthium strumarium. Understanding their population dynamics, particularly weed seedling emergence patterns, is important for the timely implementation and the success of weed management strategies. Identifying the sources of variation of emergence patterns could greatly improve our ability to predict emergence timing. A three-years field study was conducted to determine the effect of environmental conditions on S. obtusifolia and X. strumarium seedling emergence and seedbank potential. The experiment was conducted with two seed sources; X. strumarium burs and S. obtusifolia seeds from a single maternal plant source, and X. strumarium burs and S. obtusifolia seeds from multiple maternal plant sources, both being exposed either to 5 cm burial depth (buried) or left on the soil surface (soil surface) in the fallow or planted in spring after their storage under chilled (chill) or room temperature (no chill) conditions. X. strumarium and S. obtusifolia seedling emergence was lower from burs and seeds that were planted in the soil in September as compared with the chill and/or no chill seeds/burs stored for six months. X. strumarium seedling emergence was reduced from 37 to 1% when burs were left on the soil surface when compared to buried burs. S. obtusifolia seedling emergence was reduced from 47 to 13% when seeds were left on the soil surface as compared to buried. At the end of the experimental period, the soil seedbank of X. strumarium had been significantly depleted, whereas the remaining seeds of S. obtusifolia were viable. Full article

Weeds are mainly controlled with herbicides in intensive crop production, but this has resulted in increasing problems with herbicide-resistant weeds and public concerns about the unwanted side-effects of herbicide use. Therefore, there is a need for new alternative methods to reduce weed problems. One way to reduce weed infestation could be to collect or kill weed seeds produced in the growing season. Crop and weeds are harvested simultaneously with the combine harvester, but most of the weed seeds are returned with the chaff to the field creating new problems in future growing seasons. During the harvesting process, the harvester produces heat. Under normal harvest conditions, the exhaust gas temperature measured directly behind the turbocharger of the engine of a combine harvester may reach between 400 °C and 480 °C depending of the size of the engine. These high temperatures indicate that there is a potential for developing a system which perhaps could be utilized to kill or damage the weeds seeds. We investigate how much heat is needed to damage weed seeds significantly and focuses on the germination patterns over time in response to these treatments. We investigated if heat treatment of weed seeds could kill the seeds or reduce seed vigour or kill the seeds before they are returned to the field. The aim is to avoid harvested viable weed seeds being added to the soil seed bank. During the threshing and cleaning process in the combine harvester, most weed seeds and chaff are separated from the crop grains. After this separation, we imagine that the weed seeds could be exposed to a high temperature before they are returned to the field. Seeds of nine common weed species were treated with temperatures of 50 °C, 100 °C, 150 °C, 200 °C, and 250 °C for 0, 2, 5, 10, and 20 s, respectively. Afterwards, the seeds were germinated for fourteen days. Seeds were differently affected by the heat treatments. We found that 50 °C and 100 °C was insufficient to harm the seeds of all species significantly at all durations. Heating with a temperature of 50 °C and 100 °C showed a slight tendency to break the dormancy of Alopecurus myosuroides Huds. and Papaver rhoeas L., but the results were not statistically significant. Seeds treated with 150 °C gave varying results depending on the duration and the weed species. The germination of A. myosuroides was significantly repressed when seeds were exposed to 250 °C for 5 s. Most species were significantly damaged when they were exposed to 250 °C for more than 10 s. Our results showed that there is a potential to explore how the waste heat energy produced by combine harvesters can be exploited to either kill or reduce the vigour of weed seeds before they are returned to the field with the chaff. Full article

Intercropping provides several benefits to the agro-ecosystem and plays an important role in Integrated Weed Management (IWM). In this study, we investigated the impact of living mulch in cereal crops on weed density and grain yield. Seven field experiments were conducted in Southwestern Germany. Perennial ryegrass and white clover were sown on the same day as the cereal crop (early) and when cereals had produced 3–5 leaves or the first tillers (late). Average weed density in the control plots without living mulch was 45 weeds m⁻². Perennial ryegrass and white clover significantly reduced weed density to 22 plants m⁻² and 25 plants m⁻². Sowing date of living mulch had no effect on weed density. Grain yield was equal in all treatments. The results show that living mulch can suppress weeds without competing with the cereal crop. Full article

Glyphosate is the most important herbicide globally, and horseweed (Conyza canadensis) has been one of the most commonly encountered weed species that has developed resistance to it in various parts of the world, including Greece. After glyphosate application, horseweed populations show a wide range of phenotypic plasticity in response to selection pressure. In previous work, we have proposed a herbicide resistance mechanism that is not due to a point mutation at the codon 106 of EPSP synthase but most likely due to a synchronized overexpression of EPSPS and the ABC transporter genes. In the current study, it is hypothesized that the observed phenotypic alterations and differential expression of the EPSPS gene could be attributed to epigenetic changes. DNA methylation plays a pivotal role in many biological procedures such as gene expression, differentiation, and cellular proliferation. Sodium bisulfite sequencing was used to detect epigenetic changes that occur at the C5 position of cytosine residues within CpGdi nucleotides in two horseweed populations (resistant vs. susceptible). Results show differential methylation pattern between the two populations. This work will elucidate the naturally increased resistance of C. Canadensis to glyphosate and set the bases for future development of techniques that restrict weed resistance to herbicides. Full article

Herbicide leaching is influenced by soil physical and chemical properties as well as the prevailing climatic conditions. However, little is known about leaching of mixture of herbicides in the soil, especially in tropical regions like Brazil. The objective of this study is to evaluate the leaching of ¹⁴C-mesotrione (cyclohexane-2-¹⁴C-mesotrione) alone and in a mixture with S-metolachlor and terbuthylazine in seven tropical soil columns under laboratory conditions. These soils represented a wide range of properties with varying textures, cation exchange capacity (44 to 154 mmol_c kg⁻¹), pH (6.0 to 7.7), organic carbon content (0.58 to 27.32 g kg⁻¹) and clay mineral contents (50 to 605 g kg⁻¹), which are typical of tropical soils. Mesotrione residues were observed across all soil column layers (0–30 cm) in all evaluated soils by simulating 200 mm of water for 48 h. The application of mesotrione, alone or in a mixture, does not influence the leaching of this herbicide. Leaching of mesotrione ranged from low (up 15 cm) to very high (up 30 cm and leachate) in the tropical soils and may pose a potential groundwater contamination risk. In sand and loamy sand soil, the mesotrione was quantified in the leachate at all sampling times as above 80% of the amount initially applied. Thus, mesotrione application without the prior knowledge of the soil physical and chemical properties can result in inefficient weed control on field condition due to high leaching potentials. Full article

Land degradation and soil fertility deterioration are two of the main causes of agricultural production stagnation and decline in many parts of the world. The model of crop production based on mechanical soil tillage and exposed soils is typically accompanied by negative effects on the natural resource base of the farming environment, which can be so serious that they jeopardize agricultural productive potential in the future. This form of agriculture is destructive to soil health and accelerates the loss of soil by increasing its mineralization and erosion rates. Conservation agriculture, a system avoiding or minimizing soil mechanical disturbance (no-tillage) combined with soil cover and crop diversification, is considered a sustainable agro-ecological approach to resource-conserving agricultural production. A major objective of tillage is supposed to be weed control, and it does not require very specific knowledge because soil inversion controls (at least temporarily) most weeds mechanically (i.e., by way of burying them). However, repeated ploughing only changes the weed population, but does not control weeds in the long term. The same applies to the mechanical uprooting of weeds. While in the short term some tillage operations can control weeds on farms, tillage systems can increase and propagate weeds off-farm. The absence of tillage, under conservation agriculture, requires other measures of weed control. One of the ways in which this is realized is through herbicide application. However, environmental concerns, herbicide resistance and access to appropriate agro-chemicals on the part of resource-poor farmers, highlight the need for alternative weed control strategies that are effective and accessible for smallholders adopting conservation agriculture. Farmers in semi-arid regions contend with the additional challenge of low biomass production and, often, competition with livestock enterprises, which limit the potential weed-suppressing benefits of mulch and living cover crops. This paper reviews the applicability and efficacy of various mechanical, biological and integrated weed management strategies for the effective and sustainable management of weeds in smallholder conservation agriculture systems, including the role of appropriate equipment and prerequisites for smallholders within a sustainable intensification scenario. Full article