ABSTRACT Sonchus arvensis L. is a perennial weed increasingly abundant in northern Europe, associated with organic farming and soil cultivation. The resprouting potential after disturbance and its subsequent development and growth under different site conditions remain unclear. This study investigated the effects of aboveground biomass removal of S. arvensis in Rostock (Germany), Jokioinen (Finland), and Ås (Norway). In the start year, 5 cm S. arvensis root fragments (ramets) were planted in spring under semi‐field conditions, with five replicates per treatment stage. The treatment stages were defined according to plant development stages at which aboveground biomass was removed by cutting: bud, flower, seed‐head, wilt and an uncut control. Plant development was assessed as BBCH stage in the autumn of the start year and in summer of the subsequent year. Plant growth was assessed in the subsequent year as below‐ and aboveground biomass (dry weight), number of shoots and leaves. In Ås, some ramets failed to resprout after cutting treatment in the start and subsequent year, whereas all plants resprouted in Rostock and Jokioinen. In general, biomass was higher in Rostock than in Jokioinen and Ås. Removing biomass in the start year affected plant development within the same, but not in the subsequent year. Biomass removal at the treatment stages bud and flower reduced plant growth, whereas it was hardly affected by removal at seed‐head or wilt stages compared to the uncut control. Overall, further development stages reached after resprouting in the start year were associated with reduced growth in the subsequent year.
ABSTRACT Consumers and policymakers call for crop production systems with less dependence on pesticides. In addition, national regulations require that fewer or no pesticides be used in specific protected areas, such as nature reserves or water protection areas. However, yields in organic cropping systems are criticized for being substantially lower than in conventional farming systems. A cropping system without synthetic pesticides but with mineral fertilizers (NOPS) was therefore established at two locations in Germany in 2019 to test whether the use of mineral fertilizers can support weed control and increase crop yields in synthetic pesticide‐free cropping systems. NOPS was compared to an organic (ORG) and a conventional/integrated cropping system (CONV) at two locations in a 6‐year crop rotation of winter wheat 1—maize—winter triticale (winter rye)—soybean (pea)—winter wheat 2—spring barley (clover‐grass mixture) from 2020 until 2025. It was expected that NOPS would achieve yields no more than 20% lower than CONV when synthetic pesticides were replaced by preventive and physical plant protection measures such as diverse crop rotations, stale seedbed, cover cropping, mouldboard ploughing, tolerant cultivars and camera‐guided interrow hoeing. Weeds were the dominant biotic antagonists in the study. Across all crops, weed densities were lowest in CONV. NOPS did not result in lower weed densities than ORG. NOPS achieved 19% lower yields than CONV but 24% higher than ORG. Weed competition resulted in a maximum yield loss of 67% in ORG and 48% in NOPS compared to CONV These yield gaps cannot be attributed to herbicide or fertilizer omission alone, because the systems also differed in other management practices. The results provide convincing evidence that mineral fertilization can partly reduce the yield gap between conventional and organic cropping but cannot compensate for the absence of effective herbicide‐based weed control.
ABSTRACT There is a need for effective post‐emergence (POST) herbicides to manage diverse weeds, particularly monocot weeds, in blackgram ( Vigna mungo L. Hepper) for its successful integration in cereal‐based systems of the Indo‐Gangetic Plains. However, the poor efficacy of the currently recommended POST imazethapyr against Echinochloa colona , a predominant monocot weed in these systems, limits wider adoption of blackgram. This study aimed to identify effective POST herbicides for use in blackgram, and to assess their residual effects on soil microbial populations and succeeding direct‐seeded rice ( Oryza sativa L.) productivity. Accordingly, the field experiment was conducted for 2 years (2020 and 2021) in a randomized block design with four replications, comprising seven treatments: weedy check, imazethapyr 75 g a.i. ha −1 , clodinafop‐propargyl + acifluorfen sodium (ready‐mix) 187.5 g a.i. ha −1 , propaquizafop + imazethapyr (ready‐mix) 125 g a.i. ha −1 , quizalofop‐p‐ethyl + imazethapyr (tank mix) 50 + 75 g a.i. ha −1 , imazamox + imazethapyr (ready‐mix) 60 g a.i. ha −1 , and hand weeding. A total of 11 weed species were recorded, with grasses, including E. colona, constituting nearly 80% of the total weed population, while the only sedge species, Cyperus rotundus , accounted for 7.8%, indicating predominance of monocot weeds. Propaquizafop + imazethapyr and quizalofop‐p‐ethyl + imazethapyr significantly reduced monocot weed density by 40.6%–44.1% and 27.5%–32.5% compared with the recommended imazethapyr at 25 and 65 days after sowing. Compared to the weedy check, propaquizafop + imazethapyr and quizalofop‐p‐ethyl + imazethapyr effectively suppressed total weed density (i.e., weed control efficiency, 62.8%–64.7%) and dry matter (i.e., weed control index, 72.1%–74.4%). They also produced 30.9%–37.1% higher yield over currently recommended sole imazethapyr. None of the tested herbicides exerted any detrimental effects on soil microbes or yield of the succeeding rice crop. Therefore, propaquizafop + imazethapyr or quizalofop‐p‐ethyl + imazethapyr as POST herbicide can effectively control weeds, especially monocots and may be recommended for spring–summer blackgram cultivation in rice‐based systems.
ABSTRACT Intraspecific variation in seed germination traits can strongly influence weed persistence and spread, yet its relationship with climate remains poorly resolved. We quantified population‐level variation in germination temperature and water requirements, germination speed and synchrony and seed mass in 12 Alopecurus myosuroides populations from contrasting macroclimatic regions across Europe and West Asia. To minimize maternal environmental effects, all seeds were produced under common‐garden conditions. Germination assays across controlled temperature and water‐potential gradients revealed restricted variation in lower and upper thermal limits, whereas the thermal optimum and water‐potential thresholds varied among populations, with no consistent association with macroclimatic variables. In contrast, germination speed, synchrony and seed mass showed clear geographic structuring: populations from colder and wetter regions germinated faster and more synchronously and produced heavier seeds, whereas populations from warmer and more seasonal regions germinated more slowly, less synchronously and produced smaller seeds. Multivariate analyses confirmed that geographic and climatic variation aligned primarily with germination dynamics and seed mass rather than with hydrothermal germination limits. These results indicate that population differentiation in A. myosuroides is expressed mainly through variation in the timing, coordination and vigour of early establishment rather than through divergence in physiological germination thresholds. For weed management, regional differences in emergence dynamics are therefore likely to influence the effectiveness of cultural and chemical control measures: rapid and synchronous emergence in colder, wetter systems may reduce the efficacy of delayed sowing or stale seedbeds, whereas slower and more asynchronous emergence in warmer, seasonal regions may increase escape from pre‐emergence control. Accounting for population‐level variation in germination dynamics is thus important for designing effective, regionally adapted management strategies for A. myosuroides .
ABSTRACT Arable weeds are a key component of agrobiodiversity, providing both ecosystem services and disservices: while they can reduce crop yields (disservice), they also support higher trophic levels by serving as hosts and providing floral and seed resources that sustain pollinators and natural enemies, alongside additional benefits such as reducing erosion and improving the microclimate (services). Identifying management practices that promote neutral weed communities optimising the trade‐off between their services and disservices, is essential. Organic farming and non‐inversion tillage are promoted for their environmental benefits, but weed management remains a key limitation to wider adoption of reduced tillage (RT) systems. In an organic agronomic trial initiated in 2018, we compared the effect of conventional tillage (CT) resulting in inversion tillage to a maximum depth of 25 cm and RT, defined as non‐inversion tillage at a maximum depth of 10 cm, on weed seed bank and weed standing vegetation, assessing weed species composition, diversity and functional trait‐based potential ecosystem services and disservices calculated by functional trait data extracted from published datasets. Arable weed communities were surveyed during the flowering stage over 3 years (2021–2023) for maize and 2 years (2022–2023) for winter wheat–faba bean. Compared to CT, RT resulted in a denser, richer and more even weed seed bank, without changes in dominant species. In both crops, arable weed standing vegetation under RT showed higher density, species richness and diversity. RT enhanced the potential support of weed communities to pollinators (bees, bumblebees and hoverflies) in maize, while crop‐specific responses were observed in winter wheat–faba bean, with significantly increased support mainly for bumblebees. In both crops, RT consistently increased the potential support to natural enemies (farmland birds, carabid beetles and parasitoid wasps). However, RT also increased the potential competitiveness of weed communities and, in maize, enhanced potential seed bank enrichment, indicating a higher risk of future infestations. As weed communities may still be stabilising following conversion to organic farming, longer‐term monitoring will help confirm whether these patterns persist over time.
