Summary1. This account presents information on all aspects of the biology of Ambrosia artemisiifolia L. (Common ragweed) that are relevant to understanding its ecology. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, and history, conservation, impacts and management. *Nomenclature of vascular plants follows Stace (2010) and, for non-British species, Flora Europaea.

To better manage invasive populations, it is vital to understand the environmental drivers underlying spatial variation in demographic performance of invasive individuals and populations. The invasive common ragweed, Ambrosia artemisiifolia, has severe adverse effects on agriculture and human health, due to its vast production of seeds and allergenic pollen. Here, we identify the scale and nature of environmental factors driving individual performance of A. artemisiifolia, and assess their relative importance. We studied 39 populations across the European continent, covering different climatic and habitat conditions. We found that plant size is the most important determinant in variation of per-capita seed and pollen production. Using plant volume as a measure of individual performance, we found that the local environment (i.e. the site) is far more influential for plant volume (explaining 25% of all spatial Published in "Biological Invasions doi: 10.1007/s10530-017-1640-9, 2018" which should be cited to refer to this work. variation) than geographic position (regional level; 8%) or the neighbouring vegetation (at the plot level; 4%). An overall model including environmental factors at all scales performed better (27%), including the weather (bigger plants in warm and wet conditions), soil type (smaller plants on soils with more sand), and highlighting the negative effects of altitude, neighbouring vegetation and bare soil. Pollen and seed densities varied more than 200-fold between sites, with highest estimates in Croatia, Romania and Hungary. Pollen densities were highest on arable fields, while highest seed densities were found along infrastructure, both significantly higher than on ruderal sites. We discuss implications of these findings for the spatial scale of management interventions against A. artemisiifolia.

Both weed science and plant invasion science deal with noxious plants. Yet, they have historically developed as two distinct research areas in Europe, with different target species, approaches and management aims, as well as with diverging institutions and researchers involved. We argue that the strengths of these two disciplines can be highly complementary in implementing management strategies and outline how synergies were created in an international, multidisciplinary project to develop efficient and sustainable management of common ragweed, Ambrosia artemisiifolia. Because this species has severe impacts on human health and is also a crop weed in large parts of Europe, common ragweed is one of the economically most important plant invaders in Europe. Our multidisciplinary approach combining expertise from weed science and plant invasion science allowed us (i) to develop a comprehensive plant demographic model to evaluate and compare management tools, such as optimal cutting regimes and biological control for different regions and habitat types, and (ii) to assess benefits and risks of biological control. It further (iii) showed ways to reconcile different stakeholder interests and management objectives (health versus crop yield), and (iv) led to an economic model to assess invader impact across actors and domains, and effectiveness of control measures. (v) It also led to design and implement management strategies in collaboration with the various stakeholder groups affected by noxious weeds, created training opportunities for early stage researchers in the sustainable management of noxious plants, and

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The aim of our three consecutive years (2017–2019) field trial was to obtain information as to the effect of weather conditions of the actual year as well as to assess the impact of some technological parameters such as fertilisation, the choice on the hybrid type on the yield parameters, phytosanitary conditions and mycotoxin contamination of maize. According to our results, the climatic characteristics of the years, the examined hybrid characters (FAO 310 and 490) and the fact of N-fertilisation had significant effects on yield parameters and grain moisture content. The additional N-supply did not affect the development or severity of stem rot in any of the hybrid effects. In this respect, the year effect appeared to be the decisive factor since much higher stem rot values were recorded in the plots of the longer growing season hybrids. Among the mycotoxins examined, only zearalenone and fumonisin found in the harvest were significantly influenced by the effect of the year, the length of the growing season as well as nutrient replenishment. It can be stated that the applied technological parameters have a major effect on the expression of this toxin load in maize. Dry maize stocks that have lost their water in the vegetation are predisposing factors for toxin accumulation. N-content of soil and that of plants can play a different role in mycotoxin accumulation in maize plants.