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Rumex obtusifolius (broad‐leaved dock) is a problematic weed that reduces yield and nutritional value of forage in grasslands of temperate regions worldwide. We conducted an on‐farm study to identify management practices and environmental factors that influence the risk of the occurrence of R. obtusifolius in high densities in permanent, productive grasslands used for forage production. Following a common protocol, a paired case–control design was implemented in Switzerland (CH), Slovenia (SI), and United Kingdom (UK) to compare parcels with high densities of R. obtusifolius (cases, ≥1 plant m−2) with nearby parcels free of or with very low densities of the species (controls, ≤4 plants 100 m−2). A total of 40, 20, and 18 pairs were recorded in CH, SI, and UK respectively. Parameters measured included data about management practices and history, vegetation cover and composition, and soil nutrients and texture. Across countries, increased vegetation cover reduced the relative risk of R. obtusifolius occurrence. By contrast, increased soil phosphorus and potassium and high soil bulk density raised the relative risk. These effects were consistent across countries, as no interactions between country and any of the factors were observed. The two indicator species for case parcels, Plantago major and Poa annua, were typical species of disturbed areas and fertile soils, while indicators for control parcels were characteristic of grasslands under medium to high management intensity (e.g., Festuca rubra, Cynosorus cristatus, Anthoxantum odoratum). We conclude that the risk for grassland infestation with R. obtusifolius can be significantly affected by management practices. Prevention measures should target phosphorus and potassium fertilisation to the forage plants' requirements, minimise soil compaction, and maintain dense swards. [ABSTRACT FROM AUTHOR]

Increasing evidence on environmental and economic benefits has raised farmers' interest in adopting alternative, less intensive soil management practices. To evaluate the influence of weed-competitive ability in response to a different tillage regime, a field study was conducted in maize under humid Central European climatic conditions in Slovenia. This study was established as a split-plot arrangement with three tillage practices (TPs) as the main plot: conventional (CN), conservation (CS), and no tillage (NT); this was combined with glyphosate application and the weed removal timing as the subplot. The weed removal timings were at the V3, V6, V9, V15, and R1 maize stages, with weed-free and weed season-long monitoring. The beginning and the end of the critical period of weed control (CPWC), based on a 5% maize yield loss rate, were determined by fitting the four-parameter log-logistic equations to the relative maize dry grain yield. The weed dry biomass from maize germination until the R1 growth stage in the NT TP was consistently lower than that in the CN and CS TP. Moreover, the NT TP resulted in a shorter CPWC (39 days after emergence (DAE)) compared to the CN (57 DAE) and CS (58 DAE). The results of CTWR (critical timing of weed removal) showed that less intensive tillage operations in the CS resulted in an earlier need for weed control (V2 and 23 DAE) compared to the CN (V3 and 39 DAE) and NT (V3 and 40 DAE). Our study suggests that the intensive tillage operations performed in the CN TP and the pre-sowing use of non-selective burndown herbicide in the NT delay the CTWR by more than 2 weeks, thus reducing the need for early post-emergence herbicide application in maize. [ABSTRACT FROM AUTHOR]

In 2011 and 2012, a total of 9 on-farm experiments were conducted to evaluate the effectiveness of different integrated weed management strategies (IWM) against the conventional approach (CON) in three important European maize producing countries. These sites were located in Italy, Germany and Slovenia and represent the range of various geographic, climatic and cultivation types in Europe. The IWM strategies tested were: Italy: the early-post emergence herbicide broadcast application when-if indicated by a predictive model of weed emergence after performing one scouting in the field, followed by hoeing, Germany: the early-post emergence band application combined with hoeing followed by a second hoeing and Slovenia: the harrowing at BBCH 12-13 of maize and low doses of post-emergence herbicide. Results showed that the different IWM strategies tested in the countries were similarly effective with the CON broadcast herbicide application in reducing weed density. In terms of mean weed density in the 3 countries and 2 years the efficacy of CON was significantly higher than IWM in only 2 out of 6 trials across two growing seasons. Furthermore, there were no significant differences of both management strategies in terms of grain yield. The study highlights the potential of IWM tools already available in Europe.