Browsing by Subject "weeds"

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  • Särkinen, Tiina; Poczai, Péter; Barboza, Gloria; van der Weerden, Gerard M.; Baden, Maria; Knapp, Sandra (2018)
    The Morelloid Glade, also known as the black nightshades or "Maurella" (Morella), is one of the 10 major Glades within Solanum L. The pantropical Glade consists of 75 currently recognised non-spiny herbaceous and suffrutescent species with simple or branched hairs with or without glandular tips, with a centre of distribution in the tropical Andes. A secondary centre of diversity is found in Africa, where a set of mainly polyploid taxa occur. A yet smaller set of species is found in Australasia and Europe, including Solanum nigrum L., the type of the genus Solanum. Due to the large number of published synonyms, combined with complex morphological variation, our understanding of species limits and diversity in the Morelloid Glade has remained poor despite detailed morphological studies carried out in conjunction with breeding experiments. Here we provide the first taxonomic overview since the 19th century of the entire group in the Old World, including Africa, Asia, Australia, Europe and islands of the Pacific. Complete synonymy, morphological descriptions, distribution maps and common names and uses are provided for all 19 species occurring outside the Americas (i.e. Africa, Asia, Australia, Europe and islands of the Pacific). We treat 12 species native to the Old World, as well as 7 taxa that are putatively introduced and/or invasive in the region. The current knowledge of the origin of the polyploid species is summarised. A key to all of the species occurring in the Old World is provided, together with line drawings and colour figures to aid identification both in herbaria and in the field. Preliminary conservation assessments arc provided for all species.
  • Haapala, Tapani; Palonen, Pauliina; Tamminen, Antti; Ahokas, Jukka (2015)
  • Kauppi, Katja; Rajala, Ari; Huusela, Erja; Kaseva, Janne; Ruuttunen, Pentti; Jalli, Heikki; Alakukku, Laura; Jalli, Marja (2021)
    The effect of weeds, plant diseases and insect pests on spring barley (Hordeum vulgare) and spring wheat (Triticum aestivum) grain and nutrient yield was examined. Long-term field trial data was used to assess the impact of different pests on grain yield. In the absence of pesticides, fungal diseases caused the largest annual yield-reduction in spring wheat and spring barley, 500 kg ha(-1) on average. Converting yield loss to nutrient yield loss this represented reductions of 8.1 and 9.2 kg ha(-1) in nitrogen and 1.5 and 1.6 kg ha(-1) in phosphorus, respectively. Likewise, it was estimated that weeds decrease the yield of spring barley and spring wheat for 200 kg ha(-1), which means reductions of 3.7 and 3.2 kg ha(-1) in nitrogen and 0.6 kg ha(-1) in phosphorus, respectively. For insect pests yield-reduction in spring barley and spring wheat varied between 418 and 745 kg ha(-1) respectively. However, because bird cherry-oat aphid (Rhopalosiphum padi L.) incidence data was limited, and aphids are highly variable annually, nutrient yield losses caused by insect pests were not included. Based on the current study, the management of weeds, plant diseases and insects maintain cereal crop yield and may thus decrease the environmental risks caused by unutilized nutrients.
  • Hovi, Antti (University of Helsinki, 1995)
  • Verbrugge, Laura N. H.; Dawson, Murray; Gettys, Lyn A.; Leuven, Rob S. E. W.; Marchante, Helia; Marchante, Elizabete; Nummi, Petri; Rutenfrans, Annerie H. M.; Schneider, Katrin; Vanderhoeven, Sonia (2021)
    Increasing public awareness is a prerequisite for successful management of invasive alien species (IAS). Environmental education can play an important role in this process by providing relevant learning outcomes and experiences for youth and students, as well as professionals in different sectors associated with introduction pathways or who are involved in mitigation and eradication of IAS. This paper responds to the urgent call for the inclusion of the IAS topic in education through the development, implementation and evaluation of novel and user-friendly educational materials. The aim of this paper is to describe best practices in IAS education and to share the lessons learned from eight educational projects from seven different countries. We discuss four challenges for IAS education, related to (1) inconsistent and ambiguous terminology, (2) communicating risk, (3) implementation of education materials, and (4) evaluation of learning effects. Examples of best practices are the use of smartphone applications and gaming elements, place-based education and exhibitions. We also note the importance of open access publishing of education materials to make them easily available. We intend this discussion to serve as a source of inspiration to researchers, science communicators and teachers and to spur the development of new teaching materials worldwide.
  • Lavonen, Tanja (Helsingfors universitet, 2008)
    Weeds cause hard surfaces and pavements in cities to break down more quickly than they naturally would. Weed control on hard surfaces is mainly based on herbicides, of which glyphosate is the most effective and also most widely used. However, the use of glyphosate on paved areas has been restricted in some countries because of the risk of leaching in to groundwater and watercourse. Alternative methods for weed control on urban areas include mechanical, physical and biological methods and natural product herbicides. Many of the physical methods are based on thermal effect, and the most suitable on hard surfaces are flaming, hot water and hot steam. Vinegar is an alternative herbicide that is commonly in use. Oils have been used as adjuvants in herbicides, but many plant originated oils have phytotoxic effects of their own. Herbicides based on vegetable oils are available in several countries. Steaming and vinegar were tested on hard surface weed control during three growing seasons 2005-2007. The purpose of the study was to investigate whether steaming and vinegar have an effect on the number of weeds on hard surfaces, and how many applications are required to provide adequate control. The aim of the greenhouse experiment was to compare the effects of 12 % vinegar and different concentrations of pine oil and birch oil distillate on two weed species in two different developmental stages. The aim of the third experiment was to test pine oil, birch oil distillate and vinegar for weed control in practice on the bases of ornamental trees. The experiment was carried out during summer 2007. Vinegar and steaming controlled vegetation on hard surfaces, and the best result was obtained by three applications during one growing season. In this experiment vinegar provided better control than steaming. The greenhouse experiment proved the largest concentrations of pine oil and birch oil distillate to control weeds as well as or even better than vinegar. In the field experiment birch oil distillate and pine oil were slightly more effective than vinegar. Reducing the use of herbicides in cities is an important task, and successful weed control requires careful planning. Herbicides should be used only when other means are insufficient.