Solvejg K Mathiassen

Aarhus University | AU · Department of Agroecology

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...

The targeted treatment of weeds is an expanding part of precision farming in many countries. Targeted weed treatments, using precision spray maps, reduce herbicide consumption, whilst still maintaining long term weed control. Assembling accurate spray maps is a vital part of this process. However, acceptable accuracy in spray maps is difficult to q...

Rattail fescue (Vulpia myuros (L.) C.C. Gmel.) is a self-pollinating winter annual grassy weed of winter annual crops. The problems with V. myuros are mostly associated with no-till cropping systems where glyphosate application before sowing or emergence of the crop is the most important control measure. Ineffective V. myuros control has been repor...

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 herbicide...

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....

Herbicide drift may cause adverse effects on natural and semi‐natural plant communities, and it has been debated whether the current ecological risk assessments are adequate to protect non‐target terrestrial plant species (NTTP). In this study, nine NTTPs with different lifespans (three annual/ six perennial) belonging to six different plant famili...

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 co...

Field experiments were conducted in the growing seasons of 2017/18 and 2018/19 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 . Cumu...

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...

Different techniques have been devised to detect herbicide resistance in weeds, and the overall aim from this study was to compare four different assay techniques for evaluating acetolactate synthase (ALS)-inhibiting herbicide resistance in sterile wild oat (Avena sterilis L.). A resistant sterile wild oat population (R) was collected from the whea...

Concerns around herbicide resistance, human risk, and the environmental impacts of current weed control strategies have led to an increasing demand for alternative weed management methods. Many new weed management strategies are under development; however, the poor availability of accurate weed maps, and a lack of confidence in the outcomes of alte...

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....

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, t...

This publication contains results from crop protection trials, which were carried out at the Department of Agroecology within the area of agricultural crops. Most of the results come from field trials, but results from greenhouse and semi-field trials are included. The report contains results that throw light upon: • Effects of new pesticides • Res...

For decades, significant effort has been put into the development of plant detection and classification algorithms. However, it has been difficult to compare the performance of the different algorithms, due to the lack of a common testbed, such as a public available annotated reference dataset. In this paper, we present the Open Plant Phenotype Dat...

Herbicides have been shown to reduce flower production and to delay flowering with results varying among herbicides and tested plant species. Here, we investigated the effects of herbicides on flowering in an extensive greenhouse study conducted in Canada and Denmark. The effects of low doses of five different herbicides (bromoxynil, ioxynil + brom...

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 developmen...

Accurate predictions of weed seed dispersal are important for spatial modelling of weed population dynamics. However there are few multi-year data sets available, and they are seldom analysed well. Here we gathered together and re-examined population growth and seed spread data from three grass weed species over 3 years. Using a new seed spread fun...

This publication contains results from crop protection trials, which has been carried out or organized by the Dept. of Agroecology. The report include data from trials which throw light upon: Efficacy of new pesticides, results with different control strategies including both cultivars and other IPM elements, results with fungicide resistance and...

Plant competitive interactions influence the effect of herbicides, and the effect of competitive interactions on plant responses may be important to include in the ecological risk assessment of herbicides. Here, the effect of competitive interactions and sub‐lethal doses of two herbicides on plant species was investigated in competition experiments...

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 Sca...

There is an urgent need for more integrated weed management in commercial cereal production. However, there is gap in the general understanding of crop–weed interactions and the traits contributing to weed suppression by winter cereals. In this research, we measured the above-ground competitive traits crop height, leaf area index and early ground c...

The lack of non-destructive sampling methods that allow for repeated sampling of secondary plant metabolites in the root zone is restricting the understanding of allelopathic interactions in intact plant communities. Here, we determine the robustness of silicone tube microextraction (STME) to technical and environmental effects, as well as its appl...

This study outlines a new method of automatically estimating weed species and growth stages (from cotyledon until eight leaves are visible) of in situ images covering 18 weed species or families. Images of weeds growing within a variety of crops were gathered across variable environmental conditions with regards to soil types, resolution and light...

The publication contains results from crop protection trials, which were carried out at the Dept. of Agroecology within the area of agricultural crops. Most results come from field trials, but also results from lab-testing and green house trials are included. The report contains results from testing of the efficacy of new pesticides, comparison of...

Weed suppressive potential of 33 winter wheat, 24 winter rye and 11 winter triticale cultivars recently introduced to the Scandinavian market was investigated. Competitive traits recorded were early vigor, leaf area index and crop height. Allelopathic potential was assessed by analyzing plant root and shoot material by LC-MS/MS for their content of...

Attention should be devoted to weeds evolving herbicide resistance with non-target-site resistance (NTSR) mechanism due to their unpredictable resistance patterns. Quantification of fitness cost can be used in NTSR management strategies to determine the long-term fate of resistant plants in weed populations. To our knowledge, this is the first repo...

The tetrazolium (TZ) test is an efficient way to evaluate seed viability. However, TZ protocols vary greatly among species and need to be adjusted for each. Loose silky bentgrass (Apera spica-venti) is an important grass weed in Central and Eastern Europe with very small seeds (3.0 × 0.5 mm). Due to the small size of A. spica-venti seeds, it is ver...

Herbicide resistance is an example of plant evolution caused by an increased reliance on herbicides with few sites of action to manage weed populations. This micro-evolutionary process depends on fitness, therefore the assessment of fitness differences between susceptible and resistant populations are pivotal to establish management strategies. Loo...

Over the past decades declining biodiversity has been a major concern across the world; however, preventing biodiversity declines in agricultural areas has been ineffective. Failure to adequately assess and properly regulate herbicide effects can have important implications for species richness and overall biodiversity within natural and semi-natur...

Seedling emergence traits of susceptible (S) and resistant (R) blackgrass subpopulations isolated from a single non–target-site resistant (NTSR) population were studied in controlled conditions. The seedling emergence of the R subpopulation was lower and slower than that of the S subpopulation, especially at low temperature and deep burial. The bur...

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...

This publication contains results from crop protection trials which were carried out at the Department of Agroecology within the area of agricultural crops. Most of the results come from field trials, but results from greenhouse and semi-field trials are also included. The report contains results that throw light upon: • Effects of new pesticides •...

Abstract Background Loose silky bentgrass (Apera spica-venti) is an important weed in Europe with a recent increase in herbicide resistance cases. The lack of genetic information about this noxious weed limits its biological understanding such as growth, reproduction, genetic variation, molecular ecology and metabolic herbicide resistance. This st...

Herbicide resistance is a ubiquitous challenge to herbicide sustainability and a looming threat to control weeds in crops. Recently four genes were found constituently over-expressed in herbicide resistant individuals of Lolium rigidum, a close relative of Lolium multiflorum. These include two cytochrome P450s, one nitronate monooxygenase and one g...

Vulpia myuros is a winter annual grass weed species belonging to the Poaceae family. V. myuros was first reported as a weed problem in red fescue in Denmark in 2000 and is now a significant weed problem in winter annual crops. V. myuros is hard to control due to a high natural tolerance to ACCase-inhibitors. Surviving plants have an extensive growt...

A series of pot experiment were conducted to study the impact of growth stage on metamitron efficacy. Eight weed species were grown outdoors and metamitron was applied at the cotyledon stage, cotyledon with emerging true leaves, 2-leaf and 4-leaf stage. In two experiments the soil versus foliar activity was compared; soil activity was obtained by a...

Retention and biological activity of droplets of glyphosate deposited onto plant leaves using a Drop on Demand inkjet printer application system, was examined on pot-grown Brassica napus, Solanum nigrum, Chenopodium album, Silene noctiflora and Echinocloa crus-galli plants. Retention was measured at leaf angles of 0 o , 20 o , 35 o and 45 o. Retent...

The effect on Ambrosia artemisiifolia (common ragweed) of combining cutting and herbicide application was studied in pot experiments in Germany and Denmark in 2013. Single plants of common ragweed were established in 2 L pots in glasshouses. Two cutting treatments were conducted: cutting to 10 cm height at the beginning of male budding (BBCH 51-59)...

The continuous increasing of herbicide resistance urges the implementation of Integrated Weed Management (IWM) to establish more sustainable cropping systems. An important question is whether application of IWM strategies can provide a sufficient level of weed control, and perhaps favour a reversion of the resistance evolution process. Theoretical...

The question on intraregional versus inter-regional variability in herbicide sensitivity for weed populations is of major importance, both in extrapolation of model parameters and in herbicide zonal approval procedures. We hypothesised that inter-regional variability in herbicide sensitivity for field populations would be the same as intraregional...

This publication contains results from crop protection trials in agricultural crops and focuses to a major extend on results with different pesticides, data on pesticide resistance as well as trial results from specific IPM-related activities. The publication is a summary of the publicly available results generated mainaly from field trial activiti...

Alopecurus myosuroides Huds is one of the most important grass-weeds in North-western Europe and is also the most important herbicide-resistant weed species in European agricultural systems. Fifty-three Danish A. myosuroides populations, previously confirmed to be fenoxaprop-P resistant, were evaluated for five and two known mutation points within...

Biodiversity within European semi-natural biotopes in agro-ecosystem is declining, and herbicide drift from neighbouring fields is considered as an important factor for the decline. The aim of the present study was to investigate whether the growth and competitive interactions in a model system of two perennial grass species, Festuca ovina and Agro...

Herbicides are still the most effective way of weed control. Evolved resistance to herbicides may become a serious and escalating problem in crop production systems worldwide. The challenge in avoiding the dissemination of resistant populations is an early exploration of resistance. Our study aimed at answering the questions: (1) Can the intra-fiel...

The report describes results from field trials from arable crops with pesticide carried out at Aarhus University - Flakkebjerg in 2013. It provides data from IPM related activities including screening for cultivar resistance to several cereal diseases.

Crop Protection Online (CPO) is a decision support system, which integrates decision algorithms quantifying the requirement for weed control and a herbicide dose model. CPO was designed to be used by advisors and farmers to optimize the choice of herbicide and dose. The recommendations from CPO for herbicide application in spring barley in Denmark...

Declining plant diversity and abundance have been widely reported in agro-ecosystems of North America and Europe. Intensive use of herbicides within cropfields and the associated drift in adjacent habitats are partly responsible for this change. The objectives of this work were to quantify the phenological stages of non-target plants in in-situ fie...

The ecological success of a plant species is typically described by the observed change in plant abundance or cover, but in order to more fully understand the fundamental plant ecological processes, it is necessary to inspect the underlying processes of survival and colonization and how they are affected by environmental conditions. A general ecolo...