Theresa Reinhardt Piskáčková

The grass species Alopecurus myosuroides Huds., Lolium multiflorum Lam. and Bromus sterilis L. are abundant and dominant weeds in European winter wheat fields. They cause significant yield losses and impede grain harvest. Many populations of these grass weeds are resistant to one or more herbicide modes of action in Europe. Therefore, additional non‐chemical control measures are needed to suppress these weed species. In this study, grass weed panicle cutting, chaff milling and a combination of both treatments were examined as potential control measures to reduce the entry of grass weed seeds into the soil seed bank. An untreated control and a standard herbicide application served as control treatments. Five field trials in winter wheat were carried out in 2023/2024, two with A. myosuroides at the University of Hohenheim (UHOH, Germany) and the Julius Kühn‐Institute (JKI, Germany), two with L. multiflorum at UHOH and Bavarian State Research Centre for Agriculture (LfL, Germany) and one with B. sterilis at the Czech University of Life Sciences (CZU, Czech Republic). For the cutting treatment, panicles of the three grass weeds were cut closely above the winter wheat canopy and removed from the field two times during the vegetation period. As part of the second treatment, winter wheat chaff was collected during or after harvest and processed after harvest with a stationary impact mill. Herbicide efficacy, grass weed panicle density, grass weed seed density and seed germination rate were measured for each treatment. Grain yield was assessed at the time of winter wheat harvest. Cutting above the wheat canopy reduced panicle density of A. myosuroides on average by 22%, B. sterilis by 47% and L. multiflorum panicle density by 63%. At the second date of cutting, almost all panicles of B. sterilis were below the wheat canopy. Therefore, only one cut was performed in the field trials at CZU. Post‐harvest milling destroyed on average 39% of the A. myosuroides seeds, 78% of the L. multiflorum seeds and 90% of the B. sterilis seeds in the chaff fraction. However, these grass weeds retain only 40%–60% of their seeds on the panicles until harvest, which impedes the efficacy of the treatments. Therefore, the combination of cutting and milling led to a reduction in weed seed density of only 10% for A. myosuroides , 63% for B. sterilis and 85% for L. multiflorum . In conclusion, panicle cutting and chaff milling constitute effective strategies for long‐term population control of L. multiflorum . The data of a single, non‐repeated study show that B. sterilis weed seed return can also be reduced with panicle cutting and chaff milling. However, both treatments did not decrease weed competition and yield losses in the year of treatment. Therefore, these measures need to be combined with other preventive and direct weed control measures.

Catch crops play a vital role in agricultural systems by contributing to biomass production, nutrient retention, and carbon sequestration. Among these, species from the Brassicaceae family are particularly valuable due to their rapid biomass accumulation, biofumigant properties, and adaptability to diverse environmental conditions. This study presents the first systematic evaluation of biomass characteristics for six non-traditional Brassicaceae species under Central European conditions, alongside commonly cultivated representatives of the family. Field experiments were conducted in Eastern Bohemia from 2021 to 2023 to assess biomass production in nine Brassicaceae species. Four sowing dates were evaluated, with plant sampling determining aboveground and underground biomass. The results revealed significant species-specific differences in biomass accumulation. Sinapis alba and Raphanus sativus exhibited the highest biomass, while Brassica napus and Crambe abyssinica had the lowest. A positive correlation between aboveground and underground biomass was observed across species, though root-to-shoot ratios varied, influencing carbon allocation patterns and soil organic matter inputs. Overall, the results demonstrate that sowing date is a critical factor influencing growth dynamics and reproductive development in these underutilized Brassicaceae species. By identifying optimal planting windows, this study contributes to improved management strategies aimed at maximizing biomass production while supporting sustainable cropping practices, including enhanced soil organic carbon stabilization and reduced nutrient losses.

Certain plant species have the potential to establish themselves in agricultural fields, especially when they are already present nearby. Their spread can be influenced by improper management or intentional and unintentional introduction. Recently, cut-leaved gipsywort (Lycopus exaltatus L.) has been increasingly present in some row crops, where it was previously found only along field edges and irrigation channels, with no data about their presence in crops. Currently, no effective control methods for this rhizomatous species have been reported. To address this, 11 herbicides commonly used for weed management in major crops were evaluated in greenhouse studies. These included bentazon, dicamba, foramsulfuron, glyphosate, halauxifen-methyl, imazamox, mesotrione, nicosulfuron, tembotrione, thifensulfuron-methyl, and tribenuron-methyl. A dose-response study was conducted to identify the most effective option for cut-leaved gipsywort control using existing crop protection products. The study evaluated percentage reductions in dry biomass and canopy cover. The results suggest that bentazon, as the only nonsystemic herbicide, was least effective in controlling cut-leaved gipsywort with an effective dose (ED₉₀) estimated at 1.5 × of the recommended labeled rate, or 2,205 g ai ha⁻¹. Plants exposed to dicamba exhibited no regrowth at the field-use rate. Cut-leaved gipsywort may regrow when foramsulfuron, mesotrione, nicosulfuron, and tembotrione are applied at the recommended field-use rates. Halauxifen-methyl and imazamox were most effective, with estimated ED₉₀ values of 0.21 × (0.85 g ai ha⁻¹) and 0.4 × (16.14 g ai ha⁻¹), respectively, which are lower than the recommended labeled rates. Although reduced rates are not recommended because good herbicide stewardship practices should aim to prevent the development of herbicide resistance, with both halauxifen-methyl and imazamox, cut-leaved gipsywort exhibited no regrowth when one-half of the recommended labeled rates were applied.

One of the positive roles of weeds may be their potential use as medicinal plants. The aim of this article is to evaluate the occurrence and distribution of weeds with pharmaceutically important active substances on arable land in the Czech Republic in organic farming. In 2006–2018, a phytocoenological survey was performed on selected organic farms in different production areas representing various climate and soil conditions and in different crops. A total of 223 species were found throughout the survey and of those, 56 species were identified to have a pharmaceutical significance. The effect of different production area and crops on the occurrence of these species was found statistically significant; however, most of the plants were not strongly associated with a particular region or crop. Among the species that were both frequent and with high mean cover are Cirsium arvense, Polygonum aviculare, Capsella bursa-pastoris, Stellaria media, Galium aparine, Elytrigia repens, Convolvulus arvensis, Fumaria officinalis, Centaurea cyanus, Descurainia sophia and Equisetum arvense . Recognizing possible benefits of ecosystem services provided by arable weeds and finding opportunities for organic farmers to have new seasonal markets may help improve sustainability of small farming operations.

Plant names carry a significant amount of information without providing a lengthy description. This is an efficient shorthand for scientists and stakeholders to communicate about a plant, but only when the name is based on a common understanding. It is standard to think of each plant having just two names, a common name and a scientific name, yet both names can be a source of confusion. There are often many common names that refer to the same plant, or a single common name that refers to multiple different species, and some plants have no common name at all. Scientific names are based upon international standards; however, when the taxonomy is not agreed upon, two scientific names may be used to describe the same species. Weed scientists and practitioners can easily memorize multiple plant names and know that they refer to the same species, but when we consider global communication and far-reaching databases, it becomes very relevant to consider two sides of this shift: (1) a need for greater standardization (due to database management and risk of lost data from dropped cross-referencing); and (2) the loss of local heritage, which provides useful meaning through various common names. In addition, weed scientists can be resistant to changing names that they learned or frequently use. The developments in online databases and reclassification of plant taxonomy by phylogenetic relationships have changed the accessibility and role of the list of standardized plant names compiled by the Weed Science Society of America (WSSA). As part of an attempt to reconcile WSSA and USDA common names for weedy plants, the WSSA Standardized Plant Names Committee recently concluded an extensive review of the Composite List of Weeds common names and had small changes approved to about 10% of the list of more than 2,800 distinct species.

In order to achieve integrated weed management, precision timing is just as important an aspect to consider as spatial precision: the stage of the plant at the time of action will impact its successful control or survivability and thus the selection pressure for herbicide resistance. Weed emergence models are one aspect of this precision timing, but they are yet underutilized. One critique has been that models based on bare ground emergence are not always validated with emergence in the crop, and yet also residual herbicides and their timing may also affect the model. In this work, we compare emergence of Echinochloa crus-galli on bare ground and in maize and the impact of early post-residual herbicides at several timings. Experiments on bare ground and in maize were set in Prague, Czech Republic, in 2021, 2022, and 2023. Bare-ground quadrats of 0.25 m² were randomly assigned in a space of 100 m². Maize plot treatments of four herbicides at each of five timings were assigned in a randomized complete block design (dimethenamid-P at 1008 g ai ha⁻¹, pethoxamid at 1200 g ai ha⁻¹, isoxaflutole at 96 g ai ha⁻¹, and mesotrione at 480 g ai ha⁻¹). Three 0.25 m² quadrats were enumerated in each plot from first emergence to full canopy closure (May to July). Model fit to emergence from the bare-ground plots using thermal time with a base temperature of 10 °C resulted in an AIC of −494. The bare-ground model was validated with emergence from the nontreated control plots in maize in 2022 and 2023, which accounted for over 85% of the variability in observed emergence. At canopy closure, total emergence since herbicide application was affected by herbicide and application timing. All herbicides at all timings reduced the emergence after application except for mesotrione. When beginning thermal time from the day of application, the emergence pattern after mesotrione application at all timings could be modeled with a single equation. E. crus-galli had a reliable emergence pattern within a local population; the predictive model created using bare-ground plots adequately predicted emergence in maize. This information can be used to time herbicides to coincide with the most effective moment in the flush in areas where E. crus-galli is the driver weed species.

Adoption of the new biofuel crop carinata (Brassica carinata A. Braun) in the southeastern United States will largely hinge on sound agronomic recommendations that can be economically incorporated into and are compatible with existing rotations. Timing of weed control is crucial for yield protection and long term weed seed bank management, but predictive weed emergence models have not been as widely studied in winter crops for this purpose. In this work, we use observed and predicted emergence of a winter annual weed community to create recommendations for timing weed control according to weed and crop phenology progression. Observed emergence timings for four winter annual weed species in North Carolina were used to validate previously published models developed for winter annual weeds in Florida by accounting for temperature and daylength differences, and this approach explained over 70% of the variability in observed emergence. Emergence of stinking chamomile (Anthemis cotula L.) and cutleaf evening primrose (Oenothera laciniata Hill.) followed biphasic patterns comparable to wild radish (Raphanus raphanistrum L.), which were predicted with previously published models accounting for 82 and 84% of the variation, respectively. Using the predictive models for weed emergence and carinata growth, critical control windows (CCW) were estimated for Clayton, NC and Jay, FL, according to different planting dates. The results demonstrated how early planting coincided with the emergence of three competitive winter weeds, but early control could also remove a large proportion of the predicted emergence of these species. The framework for how planting timing will affect winter weed emergence and crop growth will be an instructive decision-making tool to help prepare farmers to manage weeds in carinata, but it could also be useful for weed management planning for other winter crops.