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Spray water quality parameters such as hardness, pH, alkalinity, turbidity, and total dissolved solids (TDS) can influence the performance of herbicides. Polyvalent cations found in hard water can reduce the efficacy of post-emergence herbicides that are weak acids. Various approaches have been proposed to mitigate the negative effects of spray water properties on herbicide performance. Water conditioning adjuvants are designed for overcoming the adverse effects of hard water. One group of adjuvants are nitrogen containing compounds such as ammonium sulfate (AMS). The ability of AMS to overcome hard water antagonism is well-documented but the positive effect of other ammonium compounds are variable and depend on herbicides and weed species. Other adjuvant groups that can overcome effects of poor spray quality are ethoxylated amine surfactants, organic acids and ethylenediaminetetraacetic acid (EDTA). Water quality is poor in many parts of the world, and accordingly, the study of water property effects on herbicide performance is needed to optimize use, and prevent overuse, of herbicides.

Lolium spp. are troublesome weeds mainly found in winter cereal crops worldwide, including Europe. In recent years resistant mechanisms have been evolved to several important herbicides. In this study we investigated the mechanisms responsible for conferring glyphosate resistance in some Lolium spp. populations. A holistic approach was used, based on dose-response experiments, determination of shikimic acid concentration in plant leaf tissue, as well as molecular analyses. More specifically, in three Lolium spp. populations the existence of a mutation in the Pro-106 codon of the 5-enolpyruvylshikimate-3 phosphate synthase (EPSPS) gene was investigated as well as the relative transcript levels of four ABC-transporter genes were monitored at three time points after glyphosate application. The results demonstrated that glyphosate resistance is a multifactor phenomenon. Relative transcript levels of the ABC-transporter genes were abundant at very early time points after glyphosate treatments. Dose-response experiments and shikimate analyses were in accordance with the findings of the quantitative PCR (qPCR) analyses. We suggest that relative expression ratio of ABC-transporter genes can be a useful tool to rapidly identify Lolium spp. populations resistant to glyphosate.

Translocation of metabolites between different plant species provides important hints in understanding the fate of bioactive root exudates. In the present study, targeted and untargeted mass spectrometry-based metabolomics was applied to elucidate the transfer of bioactive compounds between rye and several crops and weed species. Our results demonstrated that benzoxazinoids (BXs) synthesized by rye were taken up by roots of neighbouring plant species and translocated into their shoots. Furthermore, we showed that roots of rye plants took up compounds originating from neighbouring plants. Among the compounds taken up by rye roots, wogonin was detected in the rye shoot, which indicated a root-to-shoot translocation of this compound. Elucidating the transfer of bioactive compounds between plants is essential for understanding plant–plant interactions, developing natural pesticides and understanding their modes of action.

This presentation shows the results of a study investigating the performance of three legumes (Medicago sativa, Medicago polymorpha, and Trifolium subterraneum) as a IPM tool in a relay intercropping system with durum wheat. The study was conducted near Pisa (Italy) in a low-input Mediterranean cropping system for two consecutive wheat-sorghum rotations to assess the effects of relay intercropping of legumes on weeds at crop rotation level. During the intercropping period legumes reduced weed biomass up to 90% compared with the control (wheat sole crop), without negative impact on yield. After wheat harvest, legumes persisted in the field and biomass production level determined their weed control capacity. Medicago sativa and Trifolium subterraneum established a suppressive mulch and reduced weed biomass up to 90 % compared with the control whereas no significant effect was observed for Medicago polymorpha. In the subsequent spring legumes were incorporated into the soil and sorghum was sown. Residual effects of Medicago sativa significantly reduced weeds biomass by the 50% in sorghum compared with the control. Results of this experiment confirmed that the biomass production is a good indicator of the weed control ability of legumes. However, biomass did not fully explain the variability in weed control capacity of the selected legumes. Allelochemical effects of legumes may also be involved. Studying the allelochemical properties of legumes can be difficult under field conditions and therefore two additional laboratory experiments were conducted to deepen the knowledge about the chemical interactions between wheat, legumes, and weeds during two critical phases for weed control: the intercropping period and the period after the incorporation of legume residues into the soil. An intercropping pattern was created in pots to explore the effect of the co-cultivation with wheat on the biosynthesis and root exudation of flavonoids in legumes. Flavonoids with potential allelochemical activity such as daidzein, genistein, medicarpin, formononetin and kaempferol significantly increased in plant tissues and root exudates of the legumes in response to co-cultivation with wheat. An additional pot experiment was carried out to investigate the allelopathic effect of the legume fresh biomass on the germinability of four weed species (Alepecurus myosuroides, Lolium rigidum, Chenopodium album and Sinapis alba). To simulate the incorporation of legumes before the sorghum sowing, legume fresh leaves were grinded and mixed with field soil at two concentrations: 25 and 50 g/l. Results of this experiment were consistent with what had been observed under field conditions and confirmed that Medicago sativa has the highest allelochemical potential compared with the Trifolium subterraneum and Medicago polymorpha. This research was supported by the H2020 project IWMPRAISE (grant number 727321) and FL had a PhD scholarship from Scuola Superiore Sant’Anna in Pisa

Rimsulfuron is commonly used to control common lambsquarters (Chenopodium album L.) and redroot pigweed (Amaranthus retroflexus L.) in potato (Solanum tuberosum L.) fields. Comparing rimsulfuron absorption and metabolism patterns in these two weed species with potato could provide crucial information to optimise herbicide application in the field. Hence, an experiment was conducted in Denmark and Iran to evaluate the absorption and metabolism of rimsulfuron at the application rate of 30 g ha−1 in potato, common lambsquarters and redroot pigweed. Seedlings at the 2- to 4-leaf stage were foliar treated with rimsulfluron and plant tissues were harvested at 0, 1, 4, 8, 24 and 48 h after treatment (HAT) to measure the rate of herbicide absorption and metabolism using HPLC. Absorption and metabolism of rimsulfuron differed between potato and weed seedlings. This explains the different susceptibility to rimsulfuron in potato, redroot pigweed and common lambsquarters. Redroot pigweed, the most sensitive species in this study, showed the highest rate of absorption and lowest rate of the herbicide metabolism. Common lambsquarters, a species with an intermediate sensitivity, revealed moderate rimsulfuron absorption and metabolism levels. Potato, the tolerant crop species to rimsulfuron, showed the lowest and highest rate, respectively, of absorption and metabolism.

This study aimed to elucidate the chemical response of hairy vetch (Vicia villosa Roth) to interspecific competition by rye (Secale cereale L.). Hairy vetch plants were grown as target plants in a mixture with different densities of rye plants (0, 1, 2, and 4). Twelve flavonoids in the shoot, root, and root exudate of hairy vetch plants were quantified by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Kaempferol 3-O-{β-D-rhamnosyl-(1->6)-[β-D-xylosyl)-(1->2)]-β-D-galactoside} (Kaempferol-Rha-Xyl-Gal) was the predominant flavonoid found in shoots, roots, and root exudate of hairy vetch plant. Co-cultivation of hairy vetch with one rye plant increased the concentration of kaempferol-Rha-Xyl-Gal in hairy vetch root exudates. However, the concentration was reduced when co-cultivated with 2 or 4 rye plants. This study revealed that low levels of competition increased root exudation of kaempferol-Rha-Xyl-Gal, while higher levels of competition negatively affected production and root exudation of kaempferol-Rha-Xyl-Gal by hairy vetch.

Plants compete with their neighbors about the limited resources available to them. Plants under induced stress resulting from competition may alter their metabolome to increase their resilience or enhance their defense mechanisms. In the present study, rye (Secale cereale) plants were cocultivated with different densities (3, 12, and 18 plants per pot) of Austrian pea (Pisum sativum subsp. arvense), hairy vetch (Vicia villosa), and Alexandrian clover (Trifolium alexandrinum L.) to elucidate the changes in the rye metabolome in response to the different levels of competition. Global metabolic profiling by liquid chromatography triple quadrupole tandem mass spectrometry (LC-QqQ-MS), liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS), and gas chromatography time-of-flight mass spectrometry (GC-TOF-MS) was performed on rye plants, and the acquired data were analyzed using uni- and multivariate statistics. Targeted analysis showed that a high level of competition reduced the concentration of aglycone benzoxazinoids (BXs) and increased glycoside BXs in rye roots. Untargeted metabolomics analysis indicated an increase in the rye root content of the allelopathic compounds 4-hydroxybenzoic acid and uracil in response to competition. Untargeted analysis of rye shoots revealed that the plant competition increased the d-pyroglutamic acid, which is an elicitor of reactive oxygen species (ROS). Our results have enhanced the knowledge of the biochemical response of plant species to cocultivation.

Plants have evolved advanced chemical defense mechanisms, including root exudation, which enable them to respond to changes occurring in their surroundings rapidly. Yet, it remains unresolved how root exudation affects belowground plant-plant interactions. The objective of this study was to elucidate the fate of benzoxazinoids (BXs) exuded from the roots of rye (Secale cereale L.) plants grown with hairy vetch (Vicia villosa). A rapid method that allows nondestructive and reproducible chemical profiling of the root exudates was developed. Targeted chemical analysis with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was performed to investigate the changes in the composition and concentration of BXs in the rye plant, and its root exudate in response to cocultivation with hairy vetch. Furthermore, hairy vetch plants were screened for the possible uptake of BXs from the rhizosphere and their translocation to the shoot. Rye significantly increased the production and root exudation of BXs, in particular 2-β-d-glucopyranosyloxy-4-hydroxy-1,4-benzoxazin-3-one (DIBOA-glc) and 2-β-d-glucopyranosyloxy-4-hydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA-glc), in response to cocultivation with hairy vetch. DIBOA-glc and DIMBOA-glc were absorbed by the roots of the cocultivated hairy vetch plants and translocated to the shoots. These findings will strongly improve our understanding of the exudation of BXs from the rye plant and their role in interaction with other plant species.

The glyphosate controversy before the renewal of the authorization of glyphosate in the European Union (EU) once again turned the spotlight on pesticide regulation in the EU. In the EU, pesticides are attracting more public attention than in other parts of the world, and many nongovernmental organizations specifically target pesticide regulation, trying to influence politicians and other decision makers. Following an overview of the EU pesticide legislation and the impact hitherto on EU agriculture, this paper outlines the glyphosate controversy and presents the outcome of desk studies conducted in Germany, the United Kingdom, France, and Sweden on the potential effects of a glyphosate ban on agricultural productivity and farm income. All studies concluded that the loss of income depends very much on farm type and cropping practice, but they all reached the conclusion that particularly no-tillage farming/conservation agriculture will be facing severe problems without glyphosate to control weeds and terminate cover crops. No-tillage/conservation agriculture is viewed as an effective strategy to prevent soil erosion and loss of nutrients, which could become larger problems without glyphosate. Other issues highlighted in the studies were the impact on resistance management, as glyphosate is largely seen as a “herbicide-resistance breaker.” Without glyphosate, fundamental changes in farming practices in the EU are required, and it is hard to imagine that they will come without a cost, at least in the short term.

This paper presents and discusses the “PesticideLoadIndicator” package, a new R-package to compute potential environmental and health effects of pesticide applications using the Danish ‘Pesticide Load’ indicator. The implementation in the R Statistical Language makes it easy for researchers, practitioners and institutions to compare potential pesticide risks for a wide range of applications and compute risk indicators at field-, crop-, farm-, regional- or national level. The tool is publicly available. It provides a possibility for the direct integration of pesticide properties needed for indicator computation (ecotoxicity, environmental fate and human health), from the Pesticide Properties Database or other sources and allows users to change default reference values and weights., Computers and Electronics in Agriculture, 191, ISSN:0168-1699, ISSN:1872-7107

Due to natural tolerance to most widely used herbicides for grass weed control, prosulfocarb as pre-emergence or early post-emergence herbicide and mesosulfuron + iodosulfuron as post-emergence herbicide are the mainstays of any chemical control program for Vulpia myuros in Denmark. However, farmers often report variable efficacy of these herbicides on V. myuros compared to other grass weeds. Dose–response experiments were conducted to evaluate the performance of prosulfocarb and mesosulfuron + iodosulfuron on V. myuros. Prosulfocarb was sprayed at different plant growth stages to study the influence of plant growth stage on the performance of prosulfocarb on V. myuros in comparison with the more susceptible grass weed species Apera spica-venti. Doses causing 50% reduction in response variable (ED50) were estimated from the dose–response analysis. The ED50 values revealed a higher tolerance of V. myuros to prosulfocarb and mesosulfuron + iodosulfuron than A. spica-venti. The relative difference in the effectiveness of prosulfocarb between V. myuros and A. spica-venti was constant among plant growth stages studied. The highest levels of V. myuros control were achieved when prosulfocarb was sprayed pre-emergence (BBCH 00), while the control substantially declined at later growth stages. The results from the current study document the tolerance of V. myuros to prosulfocarb and mesosulfuron + iodosulfuron and highlight the importance of optimization of prosulfocarb spray timing for achieving maximum control of V. myuros.

Translocation of metabolites between different plant species provides important hints in understanding the fate of bioactive root exudates. In the present study, targeted and untargeted mass spectrometry-based metabolomics was applied to elucidate the transfer of bioactive compounds between rye and several crops and weed species. Our results demonstrated that benzoxinoids (BXs) synthesized by rye were taken up by roots of neighboring plant species and translocated into their shoots. Furthermore, we showed roots of the rye plant took up compounds originating from neighboring plants. Among the compounds taken up by rye roots, wogonin was detected in the rye shoot, which indicates the root-to-shoot translocation of this compound. Elucidating the transfer of bioactive compounds between plants is essential for understanding plant-plant interactions, developing natural pesticides and understanding their modes of action.

In recent years, herbicide resistance has attracted much attention as an increasingly urgent problem worldwide. Unfortunately, most of that effort was focused on confirmation of resistance and characterization of the mechanisms of resistance. For management purposes, knowledge about biology and ecology of the resistant weed phenotypes is critical. This includes fitness of the resistant biotypes compared with the corresponding wild biotypes. Accordingly, fitness has been the subject of many studies; however, lack of consensus on the concept of fitness resulted in poor experimental designs and misinterpretation of the ensuing data. In recent years, methodological protocols for conducting proper fitness studies have been proposed; however, we think these methods should be reconsidered from a herbicide-resistance management viewpoint. In addition, a discussion of the inherent challenges associated with fitness cost studies is pertinent. We believe that the methodological requirements for fitness studies of herbicide-resistant weed biotypes might differ from those applied in other scientific disciplines such as evolutionary ecology and genetics. Moreover, another important question is to what extent controlling genetic background is necessary when the aim of a fitness study is developing management practices for resistant biotypes. Among the methods available to control genetic background, we suggest two approaches (single population and pedigreed lines) as the most appropriate methods to detect differences between resistant (R) and susceptible (S) populations and to derive herbicide-resistant weed management programs. Based on these two methods, we suggest two new approaches that we named the “recurrent single population” and “recurrent pedigreed lines” methods. Importantly, whenever the aim of a fitness study is to develop optimal resistance management, we suggest selecting R and S plants within a single population and evaluating all fitness components from seed to seed instead of measuring changes in the frequency of R and S alleles through multigenerational fitness studies.

Field experiments were conducted in the growing seasons of 2017 to 2018 and 2018 to 2019 to evaluate the competitive effects of rattail fescue [Vulpia myuros (L.) C.C. Gmel.] in winter wheat (Triticum aestivum L.) and to assess whether delayed crop sowing and increased crop density influence the emergence, competitiveness, and fecundity of V. myuros. Cumulative emergence showed the potential of V. myuros to emerge rapidly and under a wide range of climatic conditions with no effect of crop density and variable effects of sowing time between the two experiments. Grain yield and yield components were negatively affected by increasing V. myuros density. The relationship between grain yield and V. myuros density was not influenced by sowing time or by crop density, but crop–weed competition was strongly influenced by growing conditions. Due to very different weather conditions, grain yield reductions were lower in the growing season of 2017 to 2018 than in 2018 to 2019, with maximum grain yield losses of 22% and 50% in the two growing seasons, respectively. The yield components, number of crop ears per square meter, and 1,000-kernel weight were affected almost equally, reflecting that V. myuros’s competition with winter wheat occurred both early and late in the growing season. Seed production of V. myuros was suppressed by delaying sowing and increasing crop density. The impacts of delayed sowing and increasing crop density on seed production of V. myuros highlight the potential of these cultural weed control tactics in the long-term management programs of this species.

Vulpia myuros has become an increasing weed problem in winter cereals in Northern Europe. However, the information about V. myuros and its behavior as an arable weed is limited. Field and greenhouse experiments were conducted in 2017/18 and 2018/19, at the Department of Agroecology in Flakkebjerg, Denmark to investigate the emergence, phenological development and growth characteristics of V. myuros in monoculture and in mixture with winter wheat, in comparison to Apera spica-venti, Alopecurus myosuroides and Lolium multiflorum. V. myuros emerged earlier than A. myosuroides and A. spica-venti but later than L. multiflorum. Significant differences in phenological development were recorded among the species. Overall phenology of V. myuros was more similar to that of L. multiflorum than to A. myosuroides and A. spica-venti. V. myuros started seed shedding earlier than A. spica-venti and L. multiflorum but later than A. myosuroides. V. myuros was more sensitive to winter wheat competition in terms of biomass production and fecundity than the other species. Using a target-neighborhood design, responses of V. myuros and A. spica-venti to the increasing density of winter wheat were quantified. At early growth stages &ldquo, BBCH 26&ndash, 29&rdquo, V. myuros was suppressed less than A. spica-venti by winter wheat, while opposite responses were seen at later growth stages &ldquo, BBCH 39&ndash, 47&rdquo, and &ldquo, BBCH 81&ndash, 90&rdquo, No significant differences in fecundity characteristics were observed between the two species in response to increasing winter wheat density. The information on the behavior of V. myuros gathered by the current study can support the development of effective integrated weed management strategies for V. myuros.

Quantifying the level of ecophysiological, biochemical, and agronomical fitness of herbicide-resistant (R) and herbicide-susceptible (S) weeds is useful for understanding the evolutionary development of herbicide resistance, but also for implementing herbicide-resistance management strategies. Although germination is a key fitness component in the life cycle of weeds, germinability of S and R weeds has rarely been evaluated under stressful conditions. Germinability traits of S and non–target site resistant subpopulations of blackgrass (Alopecurus myosuroides Huds.) sharing closely related genetic background were tested under salinity, drought stress, and accelerated seed-aging (i.e., exposed to 100% relative humidity at 45 C from 0 to 134 h) conditions. In addition, the activity of three antioxidant enzymes and protein concentration of accelerated aged seeds of the subpopulations were studied. There were no differences in maximum seed germination (Gmax) and time to 50% germination between the two subpopulations under optimum conditions. However, under salinity, drought stress, and accelerated aging conditions, there were differences between the subpopulations. The salinity, drought, and accelerated aging treatments reducing Gmax of the S subpopulation by 50% were 18 dS m−1, 0.75 MPa, and 90 h, respectively, while for the R subpopulation the corresponding values were 15 dS m−1, 0.66 MPa, and 67 h. No differences were found in the activity of the antioxidant enzymes and the content of protein between non-aged seeds of the subpopulations. The aging treatments reducing the activity of catalase and superoxide dismutase enzymes by 50% were 118 and 82 h for the S subpopulation, respectively, while they were 54 and 58 h for the R subpopulation. In contrast, there were no differences in the effect of the aging treatments on the peroxidase activity and protein content between subpopulations. The results provided clear evidence that the non–target site resistant loci of blackgrass is associated with fitness costs under environmental stress.

Alopecurus myosuroides Huds. is the most abundant herbicide-resistant weed species in Western Europe. Herbicide resistance management programs may rely, amongst other things, on information about fitness of resistant sub-population i.e. the number of offspring a genotype produces and contributes to next generation. Growth and phenological development of susceptible (S) and fenoxaprop-P resistant (R) A. myosuroides sub-populations from a non-target site resistant (NTSR) Danish population was studied for two years, while the primary seed dormancy of the populations was evaluated for three years. The genetic background of the S and R sub-populations was controlled using a plant cloning technique. No statistically significant differences were observed in the development of vegetative growth stages between the R and S sub-populations. In contrast, the R sub-population required more thermal time (at least c. 40 °C d) compared with the S sub-population to reach the reproductive phenological stages including booting and flowering. There were no vegetative (biomass) and reproductive (seed production) fitness costs in the R sub-population, however, the harvest index of the R sub-population was significantly lower than of the S sub-population. Moreover, the R sub-population had a lower primary dormancy than the S sub-population. The lower primary dormancy of the R sub-population can be considered as agronomical fitness costs of the NTSR to fenoxaprop-P, if pre-sowing seedbed preparation are implemented. The results can be implemented in models simulating phenological development and in models predicting the proportion of resistant individuals in a population.

Recently, Vulpia myuros has become a problematic grass weed species in parts of Europe. It is most common in no-till cropping systems. The inherent tolerance to several selective grass weed herbicides is of serious concern to the successful management of V. myuros in arable farming. Here, we reviewed the available knowledge about the biology of V. myuros to identify knowledge gaps and assess management efforts to identify best practices for control. V. myuros is a winter-annual species producing seeds with a short dormancy that can germinate at a wide range of conditions. Seed longevity in the soil is short. Little information is available on the influence of V. myuros on crop yield but some results suggest that yield losses can be significant. The findings provide a better understanding of the weedy characteristics of V. myuros and highlight that management strategies in Europe need to be diversified and integrate preventive and cultural control methods. Finally, we identify some of the management tools that should be considered to minimize the impact of V. myuros on European farming and future needs for research to develop sustainable integrated weed management strategies.

Monitoring pesticide use is essential for assessing farming practices and the risks associated with the use of pesticides. Currently, there are neither consolidated, public data available on glyphosate use in Europe, nor a standardized categorization of its major uses. In this study, data on glyphosate sales and use in Europe were collected from multiple sources and compiled into a dataset of the agricultural use of glyphosate from 2013 to 2017. The survey shows that glyphosate represented 33% of the herbicide volume sold in Europe in 2017. One third of the acreage of annual cropping systems and half of the acreage of perennial tree crops received glyphosate annually. Glyphosate is widely used for at least eight agronomic purposes, including weed control, crop desiccation, terminating cover crops, terminating temporary grassland and renewing permanent grassland. Glyphosate use can be classified into occasional uses&mdash, i.e., exceptional applications, triggered by meteorological conditions or specific farm constraints&mdash, and recurrent uses, which are widespread practices that are embedded in farming systems and for which other agronomic solutions may exist but are not frequently used. This article proposes a framework for the precise monitoring of glyphosate use, based on the identification of the cropping systems in which glyphosate is used, the agronomic purposes for which it is employed, the dose used and the rationale behind the different uses.

Annual ryegrass species (Lolium spp.) infest cereal crops worldwide. Ryegrass populations with multiple resistance to the acetyl coenzyme A carboxylase (ACCase) and acetolactate synthase (ALS) inhibitors are an increasing problem in several European countries. We investigated the resistance pattern and level of resistance in ryegrass populations collected in Denmark, Greece and Italy and studied the diversity of mechanisms endowing resistance, both target-site and metabolism based. All populations showed high resistance indexes (RI) to the ALS inhibitors, iodosufuron-methyl-sodium + mesosulfuron-methyl (RI from 8 to 70), whereas the responses to the two ACCase inhibitors, clodinafop-propargyl and pinoxaden, differed. The Greek and Italian populations were moderately to highly resistant to clodinafop (RI > 8) and showed low to moderate resistance to pinoxaden (RI ranged from 3 to 13) except for one Italian population. In contrast, the Danish Lolium populations showed low to moderate resistance to clodinafop (RI ranged from 2 to 7) and only one population was resistant to pinoxaden. Different mutant ACCase alleles (Leu1781, Cys2027, Asn2041, Val2041, Gly2078, Arg2088, Ala2096) and ALS alleles (Gly122, Ala197, Gln197, Leu197, Ser197, Thr197, Val205, Asn376, Glu376, Leu574) endowing resistance were detected in the Greek and Italian populations. In several plants, no mutated ALS and ACCase alleles were found showing a great heterogeneity within and among the Greek and Italian populations. Conversely, no mutant ACCase alleles were identified in the four Danish populations and only one mutant ALS allele (Leu574) was detected in two Danish populations. The expression level of nitronate monooxygenase (NMO), glutathione S-transferase (GST) and cytochrome P450s (CYP72A1 and CYP72A2) varied broadly among populations and individual plants within the populations. Constitutive up-regulation of GST, CYP72A1 and CYP72A2 was detected in resistant plants respect to susceptible plants in one Danish and one Italian population. It appears that the mechanisms underlying resistance are rather complex and diversified among Lolium spp. populations from the three countries, coevolution of both target-site resistance and metabolic based herbicide resistance appears to be a common feature in Denmark and Italy. This must be considered and carefully evaluated in adopting resistance management strategies to control Lolium spp. in cereal crops.

IWMPRAISE is the first EU Framework Research project focusing solely on weed management. Thirty-eight partners in eight European countries are working together on developing integrated weed management strategies for agricultural and horticultural crops. Per Kudsk, the coordinator of IWMPRAISE, and the work package leaders present the project, the on-going studies and some of the early outputs. Weeds are ubiquitous and cause substantial yield losses across all arable and horticultural systems. Currently, the reliance on herbicides is very high in conventional farming systems and in many European countries herbicides are the single most used group of pesticides (https://appsso.eurostat.ec.europa.eu/nui/show.do?dataset=aei_fm_salpest09&lang=en). There are several reasons for the high herbicide use, such as lack of threshold-based spraying decisions and lack of any single sufficiently effective, readily applicable, cost-effective non-chemical method. Nonetheless, two factors are driving an immediate need to change weed control practices in conventional farming: the rapidly increasing problem of herbicide resistance, exacerbated by the fact that no new herbicide sites of action have been marketed since the early 1980s, and the expectation that many of the currently used herbicides will be withdrawn from the EU market as they do not meet the human and environmental toxicity criteria set out in EU Regulation 1109/2009. In addition to these two immediate concerns, it has also been shown that herbicides have partly been responsible for recent declines in farmland biodiversity and hence a negative impact on the associated ecosystem services. The over-reliance on chemical control of weeds has highlighted the need for Integrated Weed Management (IWM) strategies that combine non-chemical management options that reduce either weed density or competition with the crop.

Plants are consistently releasing root exudates into the rhizosphere which have the potential to influence the growth and development of neighboring plant species. Root exudates contain low and high molecular weight compounds such as sugars, amino acids, secondary metabolites, phytohormones, proteins, enzymes, and polysaccharides. Although aboveground plant interactions through volatile compounds has been extensively studied, only few studies investigated role of the belowground chemical interactions between plant species. The aim of this study is to elucidate the belowground chemical interactions between rye and hairy vetch grown together as cover crop mixture. Rye and hairy vetch were cultivated alone and together in pots filled with micro glasssbeads. Plant were grown for three weeks in climate chamber and their root exudates were collected for the chemical analysis. Targeted analysis with LC-MS/MS was done to identify the changes occurring in secondary metabolite profile of the rye and hairy vetch’s root exudates as result of co-cultivation. Quantification results displayed that both hairy vetch and rye are altering their root exudation in response to rye-hairy vetch co cultivation. Hairy vetch significantly increased concentration of root exuded flavonoids such as kaempferol and pratensein in response to presence of rye. Concentrations of DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one) and BOA (1,3-benzoxazol-2-one) in rye’s root exudate were increased significantly as result of co cultivation with hairy vetch. The results from this study will increase our understanding about root exuded natural products with growth suppressive effects, which finally leads us to more sustainable plant protection system. Plants are consistently releasing root exudates into the rhizosphere which have the potential to influence the growth and development of neighboring plant species. Root exudates contain low and high molecular weight compounds such as sugars, amino acids, secondary metabolites, phytohormones, proteins, enzymes, and polysaccharides. Although aboveground plant interactions through volatile compounds has been extensively studied, only few studies investigated role of the belowground chemical interactions between plant species. The aim of this study is to elucidate the belowground chemical interactions between rye and hairy vetch grown together as cover crop mixture. Rye and hairy vetch were cultivated alone and together in pots filled with micro glasssbeads. Plant were grown for three weeks in climate chamber and their root exudates were collected for the chemical analysis. Targeted analysis with LC-MS/MS was done to identify the changes occurring in secondary metabolite profile of the rye and hairy vetch’s root exudates as result of co-cultivation. Quantification results displayed that both hairy vetch and rye are altering their root exudation in response to rye-hairy vetch co cultivation. Hairy vetch significantly increased concentration of root exuded flavonoids such as kaempferol and pratensein in response to presence of rye. Concentrations of DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one) and BOA (1,3-benzoxazol-2-one) in rye’s root exudate were increased significantly as result of co cultivation with hairy vetch. The results from this study will increase our understanding about root exuded natural products with growth suppressive effects, which finally leads us to more sustainable plant protection system.

Currently, European farmers do not have access to sufficient numbers and diversity of crop species/varieties. This prevents them from designing cropping systems more resilient to abiotic and biotic stresses. Crop diversification is a key lever to reduce pest (pathogens, animal pests and weeds) pressures at all spatial levels from fields to landscapes. In this context, plant breeding should consist of: (1) increased efforts in the development of new or minor crop varieties to foster diversity in cropping systems, and (2) focus on more resilient varieties showing local adaptation. This new breeding paradigm, called here 'breeding for integrated pest management (IPM)', may boost IPM through the development of cultivars with tolerance or resistance to key pests, with the goal of reducing reliance on conventional pesticides. At the same time, this paradigm has legal and practical implications for future breeding programs, including those targeting sustainable agricultural systems. By putting these issues into the context, this article presents the key outcomes of a questionnaire survey and experts' views expressed during an EU workshop entitled 'Breeding for IPM in sustainable agricultural systems'. © 2017 Society of Chemical Industry.

Pesticides provide growers with an effective tool for the control of damaging crop pests preventing yield losses that could jeopardise food security. In recent years the potentially adverse effects of their use on human health and the environment has received increasing attention by the public and the competent authorities. In this context reliable pesticide risk indicators are pivotal to assess the potential risk associated with the use of pesticide. Several pesticide risk indicators, serving various purposes, have been developed over the years. Recently, a new pesticide risk indicator, the Pesticide Load (PL), was introduced in Denmark. The PL has replaced the Treatment Frequency Index (TFI) as the official pesticide risk indicator. The PL consists of three sub-indicators for human health, ecotoxicology and environmental fate, respectively. For each of the three sub-indicators a pesticide load (PL) is calculated and expressed as the PL per unit commercial product (kg, L or tablet). PL for human health (PLHH) is based on the risk phrases on the product label, while PL for ecotoxicology (PLECO) is calculated on basis of the LC/LD/EC50 values of the active ingredients for acute toxicity to mammals, birds, fish, daphnia, algae, aquatic plants, earthworms and bees and NOEC values for chronic toxicity to fish, daphnia and earthworms. PL for environmental fate (PLFATE) is calculated on basis of the half-life in soil (DT50), the bioaccumulation factor (BCF) and the SCI-GROW index. PL does not consider the actual exposure, i.e. it reflects the relative risks associated with the use of pesticides. Besides using PL for monitoring the yearly trend in pesticide use and load, the PL was also used for setting up a new pesticide tax scheme and for setting quantitative reduction targets. In Denmark, it is now compulsory for farmers to upload their pesticide use data, i.e. the annual pesticide statistics and the calculation of the PL can be produced on basis of pesticide use data rather than sales data that may not reflect the actual use by farmers. Because pesticide use data is available for each farm, maps providing detailed information on pesticide use in different regions can be produced. From 2010/11 to 2013/14 only minor differences were observed in the PL and, overall, similar trends were observed for the PL and TFI. Significant geographical differences, which could be attributed to differences in crop rotations, were apparent when estimating PL for each of the four major groups of pesticides (herbicides, fungicides, insecticides and plant growth regulators). The maps produced from the pesticide use data revealed significant variation in PL for ecotoxicological effects on aqueous organisms and bees as well as environmental parameters such as leaching potential. It is suggested to use the maps to identify ‘hot spots’ and design monitoring programmes or to launch initiatives that can reduce the PL. By linking information on mode of action to each commercial pesticide product it was also possible to obtain detailed information on the use pattern of the various pesticide modes of action, which is relevant information assessing the risk of evolution of pesticide resistance.

Crop management practices such as tillage can influence the dissipation of herbicides in soil. This study aimed to determine the effects of tillage systems on soil dissipation of prosulfocarb (PSC) using two assessment methods: bioassay and high-performance liquid chromatography (HPLC) analysis. PSC was applied on plots cultivated under three tillage systems (moldboard plowing, tine tillage at 8- to 10-cm soil depth, and direct drilling) at different rates (0, 500, 1,000, 2,000, 4,000 and 8,000 g ai ha−1) and two spraying times, representing early and late sowing time of winter cereals in Denmark. The experiment was conducted over 2 yr. The soil was analyzed for PSC residues by HPLC and a bioassay, using silky windgrass as the indicator plant. Neither technique revealed an effect of tillage systems on PSC dissipation, but the LD50values estimated based on the bioassays were generally lower under direct drilling (11.7 d) than with plowing (17.5 d). Moreover, LD50estimates based on bioassay results were generally lower than those estimated with HPLC analyses. Half-life values estimated with HPLC were low and not within the range of values reported in the literature (ca. 20 d), suggesting enhanced degradation of PSC. In addition to influencing the performance of PSC against problematic weed species, an enhanced dissipation rate could also hamper the benefits of PSC in an antiresistance strategy.

Summary Annual grass weeds such as Apera spica-venti and Vulpia myuros are promoted in non-inversion tillage systems and winter cereal-based crop rotations. Unsatisfactory weed control in these conditions is often associated with a poor understanding of the emergence pattern of these weed species. The aim of this study was to investigate, understand and model the cumulative emergence patterns of A. spica-venti, V. myuros and Poa annua in winter cereals grown in three primary tillage regimes: (i) mouldboard ploughing, (ii) pre-sowing tine cultivation to 8–10 cm soil depth and (iii) direct drilling. Direct drilling delayed the cumulative emergence of A. spica-venti and V. myuros (counted together) in contrast with ploughing, while the emergence pattern of P. annua was unaffected by the type of tillage system. The total density of emerged weed seedlings varied between the tillage systems and years with a higher total emergence seen under direct drilling, followed by pre-sowing tine cultivation and ploughing. The emergence patterns of all species were differently influenced by the tillage systems, suggesting that under direct drilling, in which these species occur simultaneously, management interventions should first and foremost consider that A. spica-venti and V. myuros emerge over a longer period to avoid control failures.

Silky windgrass is a serious weed in central and northern Europe. Its importance has escalated in recent years because of its growing resistance to acetolactate synthase (ALS)-inhibiting herbicides. This study investigated the resistance level for three herbicide sites of action in eight silky windgrass populations, collected in fields neighboring a field where iodosulfuron sodium salt–resistant silky windgrass had previously been found. Target site resistance (TSR) and non–target site resistance (NTSR) mechanisms were identified, and a spatial gradient distribution hypothesis of ALS resistance was tested. Populations showed large variations in ED50values to iodosulfuron, with resistance indices (RIs) ranging from 0.1 to 372. No cross-resistance was found to other herbicide groups with the same site of action as iodosulfuron. In contrast, resistance was observed to the acetyl-CoA carboxylase inhibitor, fenoxaprop ethyl ester (RI from 0.7 to 776), while the activity of prosulfocarb, an inhibitor of long-chain fatty-acid synthesis, was unaffected. Iodosulfuron-resistant phenotypes were associated with NTSR, while fenoxaprop ethyl ester resistance was caused by both NTSR and TSR (Ile-1781-Leu mutation). A large-scale trend in the spatial distribution of resistance to ALS indicated a decreasing resistance with increased distance from an epicenter. After finer-scale analysis, less than 0.05% of the residual variation could be attributed to spatial autocorrelation. The spatial resistance pattern was not correlated with the dominant wind direction, while there was a correlation between the resistant phenotype and type of crop. This study underlines that NTSR mechanisms do not always confer broad resistance to different herbicide subclasses and site of action, hence the complex relationship to resistant phenotype. NTSR mechanisms, in particular detoxification, were present at different levels for the herbicides tested in the silky windgrass populations of this study. The factors contributing to the spatial distribution of resistance remain elusive.

Pesticides are widely used in European crop production to stabilize yields and mitigate losses from weeds, diseases and insects. Detailed spray records reported per farm and crop have for the first time been collected and analyzed for a whole country, providing good and reliable information on specific spraying patterns in arable crops. Dividing farmers into farm types provided a clear picture on how crops and crop rotations influence pesticide use patterns. On sandy soils, dairy farmers represent the farm type with the least use of pesticides while potato growers had the highest use. On clay soil, mixed crop farms had the lowest and sugar beet growers the highest use of pesticides. Across all farm types, the input of pesticides in winter wheat varies significantly, indicating a differentiated approach to pest control. While all farmers use herbicides and fungicides in winter wheat, the dairy farmers use significantly fewer insecticides and plant growth regulators in winter wheat. Farmers cultivating more than 150 ha had a higher pesticide intensity than farmers with small farms, which was observed for both sandy and clay soil farmers.

Weed science, as an integral part of agricultural production needs to evolve by moving away from its mono-disciplinary perspective at targeting weeds, sometimes a single species, through the overreliance on few single herbicide mechanisms of action. Herbicides remain a simple and cost-effective way to control weeds but they are rapidly losing their effectiveness due to evolution of herbicide resistance. Additionally, weed science has been left wanting for a strong theoretical foundation rooted in evolutionary and ecological disciplines therefore, there is a great need for a new weed management paradigm in modern agriculture based on ecological principles and nonconventional weed management approaches. The “many little hammers” concept and the “use of technological advancement” are two major integrated weed management components that are gaining momentum. Automated, robotic weed control is being rapidly developed, particularly for vegetable crops and organic agriculture. Cover crops and weed seed destruction techniques are becoming popular with growers. In the future, RNAi technology, gene editing and robotics will yield new tools for weed control. Agriculture is also moving into a new era of big data or “digital farming.” It will be interesting to see what new, unforeseen weed control solutions will be derived from this new farming approach that will allow more intelligent application and integration of weed management technologies. In an attempt to facilitate the suitability of these technologies into integrated weed management systems, this chapter reviews the strengths and weaknesses of these modern technologies and tools, and it highlights future research needs for each of these technologies.

Integrated and more sustainable weed management practices are in great demand all around the globe. The adoption of more weed-suppressive cereal cultivars could be part of an integrated weed management strategy. Recently, a study was published analysing the relative contribution of above-ground competition and allelopathy to weed suppression of Scandinavian winter cereals at the field level. The present study used the same approach with Canadian spring wheat and triticale cultivars, and confirmed the results of the previous study. The competitive traits such as leaf area index, crop height and early vigour, and the allelochemicals belonging to the chemical group of benzoxazinoids measured in the root zone were of equal importance to explain the variance of weed biomass at the field level. In addition, a dendogram showed large genetic variability for competitive and allelopathic traits in the Canadian spring cereals, providing the genetic basis for the initiation of breeding programmes for more weed-suppressive cultivars.

EU agriculture is currently in transition from conventional crop protection to integrated pest management (IPM). Because biocontrol is a key component of IPM, many European countries recently have intensified their national efforts on biocontrol research and innovation (R&I), although such initiatives are often fragmented. The operational outputs of national efforts would benefit from closer collaboration among stakeholders via transnationally coordinated approaches, as most economically important pests are similar across Europe. This paper proposes a common European framework on biocontrol R&I. It identifies generic R&I bottlenecks and needs as well as priorities for three crop types (arable, vegetable and perennial crops). The existing gap between the market offers of biocontrol solutions and the demand of growers, the lengthy and expensive registration process for biocontrol solutions and their varying effectiveness due to variable climatic conditions and site-specific factors across Europe are key obstacles hindering the development and adoption of biocontrol solutions in Europe. Considering arable, vegetable and perennial crops, a dozen common target pests are identified for each type of crop and ranked by order of importance at European level. Such a ranked list indicates numerous topics on which future joint transnational efforts would be justified. © 2016 Society of Chemical Industry

Tillage methods and crop rotation are probably the two most important cropping factors affecting weed communities, particularly when herbicide use is restricted. This study examined weed dynamics following eleven years of different tillage and crop rotation treatments. The aboveground grass weed flora was recorded each year and the content and vertical location of individual weed seeds within the plough layer (0–20 cm) were determined after 11 years of continuous mouldboard ploughing (P), pre-sowing tine cultivation to 8–10 cm soil depth (H 8-10 ) and direct drilling (D). The content of weed seeds, especially grass weeds, was determined for three distinct soil layers (0–5, 5–10 and 10–20 cm), reflecting the cultivation depths of the tillage treatments. The annual grass weeds, Apera spica-venti and Vulpia myuros , were promoted by non-inversion tillage and in the case of V. myuros also by frequent cropping of winter cereals. The two non-inversion tillage treatments caused a strong stratification of weed seeds within the plough layer, with the majority of the seeds being accumulated in the upper soil layers, at 0–5 and 5–10 cm, and markedly less so in the 10–20 cm layer. Ploughing resulted in a more even distribution between the three layers. It is suggested that in cases where severe grass weed problems have built up in a non-inversion tillage system and where changes in crop rotation are ineffective or undesirable, inversion of the upper soil layer with the lower one could be considered a management option.