Guidelines for management of common ragweed, Ambrosia artemisiifolia http:/www.EUPHRESCO.org About the publication The guidelines for management of common ragweed are based on the results of the project Strategies for Ambrosia control (AMBROSIA) funded by Euphresco 2008 – 2009. Project partners are: Aarhus University (Denmark), Agricultural Institute of Slovenia (Slovenia), Agroscope ACW (Switzerland), Julius Kühn Institute (Germany) and Copenhagen University (Denmark). Project team/editors: Niels Holst, [email protected], Aarhus Universitet AU DEPARTMENT OF INTEGRATED PEST MANAGEMENT Preben K. Hansen, [email protected], Aarhus Universitet FACULTY OF AGRICULTURAL SCIENCES AARHUS UNIVERSITY Per Kudsk, [email protected], Aarhus Universitet Solvej K. Mathiassen, [email protected], Aarhus Universitet Andrej Simoncic, [email protected], Agricultural Institute of Slovenia Mario Lesnik, [email protected], University of Maribor, Slovenia Christian Bohren, [email protected], Agroscope ACW Stephanie Waldispühl, [email protected], Agroscope ACW Arnd Verschwele, [email protected], Julius Kühn Instituttet Birte Wassmuth, [email protected], Julius Kühn Instituttet Uwe Starfinger, [email protected], Julius Kühn Instituttet Hans Peter Ravn, [email protected], University of Copenhagen Rita Merete Buttenschøn, [email protected], University of Copenhagen Authors: Rita Merete Buttenschøn, Stephanie Waldispühl and Christian Bohren (Chapter 9: Best-bet control strategies) Layout: Karin Kristensen, University of Copenhagen Front page photo: Preben K. Hansen ISBN: 9788779034549 These guidelines are also available in 6 languages at the project homepage: EUPHRESCO project AMBROSIA 2008-09. http:/www.EUPHRESCO.org 2 Contents 1. Introduction 5 References 6 2. Native range and distribution in Europe 7 Common ragweed 7 The present distribution in Europe 7 References 9 3. Identification 10 Ambrosia artemisiifolia 10 References 12 4. Species that can be mistaken for Ambrosia artemisiifolia 13 Ambrosia species that can be mistaken for common ragweed 14 Ambrosia maritima 14 Ambrosia coronopifolia 16 References 16 5. Biology and ecology of Ambrosia artemisiifolia 17 Seed bank and germination 18 References 19 6. Seed dispersal 20 Introduction pathways to new locations 20 Introduction pathways 20 Birdseed mixtures 20 Transport by machinery/equipment 21 Translocation of soil and gravel 22 Compost 22 Water courses 22 References 22 7. Preventive measures 23 How to minimise common ragweed invasion of new areas 23 Establishment of national/local policies and guidelines for best practice 23 Prevention practices 23 An awareness-raising programme 23 Surveys and monitor programmes 24 Eradication campaigns 25 Follow-up monitoring 25 References 25 3 8. Control methods 26 Mechanical control 26 Uprooting 26 Hoeing 27 Mowing/cutting 27 Ploughing 28 Chemical control (herbicides) 28 Re-vegetation 28 Mulching 28 Plastic cover 29 Biological control 29 Animal grazing 29 References 29 9. Best-bet control strategies 30 General remarks 30 Herbicide treatments 30 Mechanical treatments 31 Efficacy of control measures 31 Competition of Ambrosia 31 Best-bet strategies 32 References 32 10. Negative impact on human health and economy 33 Public health hazards 33 Pollen allergy 33 High prevalence 33 Hypersensitivity dermatitis 34 The causative agent – ragweed pollen 34 Noxious weed 35 References 36 11. Literature 38 12. Appendix 42 4 1. Introduction Ambrosia artemisiifolia (common ragweed) ragweed may cause allergy in distances has spread from its native range in North over 200 km off the site where it is America into the temperate zones of growing. Europe and in parts of Asia and Australia where it is one of the major causes of An integrated approach based on the pollen-induced allergy. The ongoing spread best-bet control strategies is needed to of Ambrosia artemisiifolia in Europe is an prevent further dispersal of common increasing problem for human health and ragweed. A successful control must be as an agricultural and non-agricultural made at all levels, i.e. the individual weed. Ambrosia artemisiifolia is causing landowner, local, regional, national and expenses of several hundreds of millions international level, and appropriate of Euros. measures must be taken. Other species of Ambrosia have been Awareness of the problem is present in the spreading to Europe together with com- afflicted European countries, but control mon ragweed, e.g. A. trifida (giant rag- measures vary from country to country. In weed) and A. coronopifolia (perennial Switzerland, where common ragweed is at ragweed). These species are also allergen- the beginning of its invasion, mandatory ic and grow as a troublesome weed in part control is declared in the ordinance of of their native range in America, but they plant protection1. Similarly, in Hungary the are rare in most parts of Europe. landowners are legally obliged to prevent common ragweed in flowering2, whereas in The invasion rate of common ragweed has other European countries e.g. Germany increased since the 1990’ies and the rate and Austria control is based on recommen- of invasion is expected to increase. Large populations of ragweed in Central Europe (Hungary, France, Italy and Croatia) may facilitate further spreading. Extensive and increasing, worldwide and intra-Communi- ty trade increases the risk of ragweed spreading. Changes in agricultural land- use with large-scale set-aside and aban- donment practices along with an increas- ing area of construction sites and wasteland provide new areas of suitable ragweed habitats. Changing climate and perhaps adaptation to local climate in Europe has expanded ragweed’s potential distribution range. The impact of common ragweed on human health is not restricted to areas invaded by the plant. Due to wind-borne spreading of the very large production of light pollen Ambrosia artemisiifolia. Mario Lešnik 5 1. Introduction A. artemisiifolia. Mario Lešnik dations and is, thus, voluntary. In Italy trade companies dealing with agricultural and France, where common ragweed is products with scientifically based, but widespread regionally, no effective legal simple and operative practical manage- mandates can help to control common ment methods to prevent further invasion ragweed. and reduce the abundance of common ragweed. The project Strategies for Ambrosia control has generated new knowledge on References common ragweed’s ecology and on the 1. Bohren C., Delabays N., Mermillod C. 2008: effect of different control measures. This Ambrosia control and legal regulation in has been elaborated to formulate best-bet Switzerland. Proc. First International strategies for control (see chapter 9). Ragweed Conference in Budapest, Hungary, September 2008. The objective of “Guidelines for manage- ment of Ambrosia” is to provide European 2. Dancza, I., Géllert, G., Pécsi, P.L. 2008: authorities, private landowners, garden- Spread and control measures against ers, constructors, birdseed producers, common ragweed in Hungary. Proc. First International Ragweed Conference in Budapest, Hungary, September 2008. 6 2. Native range and distribution in Europe The genus Ambrosia consists of about 40 occurred in the overall agricultural struc- species, most of which are native to North ture. Expansion of the cropped area of America. Only one of the species A. certain crops (e.g. sunflower), intensified maritima (Sea ragweed) is believed to be and selective weed control management native to Europe with the Mediterranean and shift from manure to slurry in animal area as its native range. Common rag- manure management have led to a weed, A. artemisiifolia, was introduced to situation with more disturbed soils. Europe together with other Ambrosia Similarly the agriculture policies, i.e. species in the 19th century. large-scale set-aside and abandonment practices, appear to stimulate the spread- Common ragweed ing of common ragweed. Bird seeds Common ragweed is the most widespread contaminated with seeds of common ragweed species worldwide and in Europe. ragweed have recently been an important According to botanical records common pathway into residential areas of Europe. ragweed was recorded in many countries Finally, the recently rising temperature in Europe in the 1860s, but the main and climate changes optimise the growth invasion within Europe, subsequent conditions for ragweed. naturalisation and spreading of common ragweed as an invasive plant started about The present distribution in Europe 20 to 25 years ago. Common ragweed is in particular wide- spread in Eastern and Central Europe. In Agricultural products contaminated with Hungary almost 80 % of the arable land is seeds of A. artemisiifolia imported from infested and ragweed has become the the USA and Canada are believed to be most important agricultural weed during the most important pathway of common the latest 20 years2. In Croatia ragweed is ragweed into Europe. especially abundant in the region of Slavonia, where it is considered a noxious Up till the 1970s, common ragweed was weed3. Ragweed has spread from South just one among several weed species Hungary and East Croatia into Serbia present in cultivated fields in part of where it is now the dominant weed species Europe, but it is now a widely distributed in soya-bean and sunflower fields. In noxious weed in several countries. The France ragweed is expanding towards the reason for this is complex. Changes have north-western regions of the country from Invasion of common ragweed in France A survey carried out by the INRA team in Dijon has established the history of the spread of ragweed in France, based on data from French herbaria1. Common ragweed was initially cultivated in a few botanical gardens as early as the 18th century. But the first reports of its presence in a natural environment date from 1863, in a field in the Allier departement in France, where the plant seems to have been introduced in batches of red clover seed from North America. Its spread then continued elsewhere in France and via different vectors, notably in forage imported for American army horses during the First World War. Popula- tions of Ambrosia artemisiifolia were described in various Atlantic harbours and in the various locations where troops remained. 7 2. Native range and distribution in Europe heavily infested areas in the Rhône Valley Many small foci have been reported from and Bourgogne1. In Italy mainly the Belgium, the Czech Republic, Austria, Lombardy province in the Po Valley is Slovenia, Germany, Switzerland and other heavily infested. European countries. They are mainly Distribution of Ambrosia pollen 2008. EAN (European Aeroallergen Network https://ean. polleninfo.eu/Ean) and epi (European Pollen Information http://www.polleninfo.org). 8 2. Native range and distribution in Europe situated in urban areas and apparently 3. Stefanic, E., Rasic, S., Merdic, S., 2008: ragweed is not yet fully established in Aerobiological and allergological impact of these countries. Further to the north ragweed (Ambrosia artemisiifolia L.) in nd common ragweed occurs only locally as an north-eastern Croatia. Proc. 2 International occasional introduction resulting from seed Symposium Intractable Weeds and Plant or fodder contamination – here it appears Invaders, Osijek, 66. not yet to have established self-sustaina- ble populations. Links http://www.europe-aliens.org/pdf/Ambrosia_ar- References temisiifolia.pdf 1. Chauvel, B., Dessaint, F., Cardinal-Legrand, C., Bretagnolle, F., 2006: The historical http://www.ambroisie.info/pages/envahi.htm spread of Ambrosia artemisiifolia L. in France from herbarium records, Journal of Biogeog- http://www.austroclim.at/fileadmin/user_up- raphy, 33 (4), 665-673. load/reports/StCl05C5.pdf 2. Kazinczi, G., Béres, I., Novák, R., Biró, K., http://www.ambrosia.ch/index.php?&idpage=64 Pathy, Z., 2008: Common Ragweed (Ambrosia artemisiifolia). A review with special regards http://www.international.inra.fr/press/the_com- to the results in Hungary. Taxonomy, origin mon_ragweed_1 and distribution, morphology, life cycle and reproduction strategy. Herbologia, 9, 55-91. https://ean.polleninfo.eu/Ean http://www.polleninfo.org 9 3. Identification The genus Ambrosia belongs to the aster maximum height of 2 metres usually with family (Asteracea) with their characteristic many branches. Ramification starts about flower head composed of numerous 2-4 cm above the ground and may include individual sessile flowers. In Ambrosia the numerous side-branches. Solitary growing flower head only consists of male flowers, individuals are often shorter, but more while female flowers are located solitarily densely ramified. or in small groups with male and female flowers in the same plant1. The leaves are compound and fernlike- toothed reaching lengths of 4-10 cm. They Ambrosia artemisiifolia are bright green on both sides with whitish Common ragweed (A. artemisiifolia) is a nerves. The lower leaves are arranged summer annual herbaceous plant, a thero- oppositely, the upper leaves are often phyte (i.e. annual plant characterised by arranged alternately on the stem of older long-term survival in seed bank). It is an plants. The stem is reddish and hairy with a erect and rather tall plant reaching a stem diameter of up to 2-4 cm at the base. male flower female flower achene pollen leaf Ambrosia artemisiifolia. Jens Christian Schou 10