Scientific name: Ageratina adenophora (Spreng.) R. M. King & H. Rob.
Family: Asteraceae (Compositae)
Risk Assessment score: (in development)
Synonymy: Ageratina trapezoidea (Kunth) R. M. King & H. Rob., Eupatorium adenophorum Spreng., Eupatorium glandulosum Kunth, non Michx., Eupatorium pasdadense Parish, Eupatorium trapezoideum Kunth
Last update: 08/07/2014
How to recognise it
Leaves: opposite, triangular to rhomboid, with 4-10 x 2-9 cm, acuminate, with a lengthy petiole, serrate on the margin, densely pubescent, dark green on the upper surface and violet on the lower surface.
Flowering: March to July.
There are other Ageratina species with white flowers with which Ageratina adenophora may be confused with. Ageratina riparia (Regel) R. King & H. Robinson has some similarity but is smaller (up to 30 cm in height) and the leaves are narrower. Ageratina ligustrina (DC.) R. M. King & H. Robinson, is also similar but the upper surface of the leaves is shiny dark green.
Characteristics that aid invasion
It propagates by seed, producing a high number of seeds (each plant may produce up to 60000 seeds/m2) which are easily dispersed by wind, water and animals.
Native distribution area
Central America (Mexico).
Distribution in Portugal
Azores archipelago (islands of São Miguel, Terceira, S. Jorge, Pico, Faial), Madeira archipelago (islands of Madeira, Porto Santo and Desertas islands).
Geographic areas where there are records of Ageratina adenophora
Europe (Spain, Italy, France, Greece) Australia, New Zealand, western USA (California), Central America (Jamaica), Asia (China, India), Africa (South Africa, Nigeria, Kenya).
Probably accidental. It’s probable that it has also been used as ornamental.
Preferential invasion environments
Cliffs, banks of watercourses and roadsides, including agricultural and disturbed areas.
It also invades natural and semi-natural areas.
Impacts on ecossystems
The rapid growth leads to the formation of impenetrable dense areas that may inhibit the development of native vegetation.
Potentially high costs in applying control methodologies, mainly in cultivated areas.
It reduces productivity in crop fields.
All parts of the plant are very aromatic, being able to cause allergic reactions.
It is a very toxic plant for mammals, especially horses.
It has allelopathic effects.
Controlling an invasive species demands a well-planned management, which includes the determination of the invaded area, identifying the causes of invasion, assessing the impacts, defining the intervention priorities, selecting the adequate control methodologies and their application. Afterwards it is fundamental to monitor the efficiency of the methodologies and recuperation of the intervened area as to perform, whenever necessary, the follow-up control.
The control methodologies used for Ageratina adenophora include:
Hand pulling: preferential methodology for invaded areas of small dimensions. In compacted substrates, hand pulling should be made during the rainy as to facilitate the removal of the root system.
Whatever the methods being used, it should be guaranteed that the extracted plants do not remain in the affected location, since their dried parts are toxic to animals.
Physical + chemical control
Cut stump method. Cut the stems close to the ground as much as possible followed by application of herbicide (active substance: glyphosate, 2, 4-D) into the cut surface, when sprouting reaches 15 to 40 cm height.
Procecidochares utilisStone (Diptera: Tephritidae) thas been used with some success in various locations (China, India, Nepal, Australia, New Zealand, South Africa) to control Ageratina adenophora. This species forms galls in the stems of Ageratina adenophora reducing the germination rate. It is supposed that gall-maker had been introduced in the Madeira island before 1971 to control Ageratina adenophora, although there are no concrete references to this.
The fungus Passalora ageratinae (=“Phaeoramularia” sp.) (Mycosphaerellales: Mycosphaerellaceae) has been used since 1987 in South Africa with moderate success in controlling Ageratina adenophora.
Visit the webpage How to Control for additional and more detailed information about the correct application of these methodologies.
Agricultural Research Council – Plant Protection Research Institute – weed">Weed Research Division (2014) Management of invasive alien plants: A list of biocontrol agents released against invasive alien plants in South Africa. Available: http://www.arc.agric.za/arc-ppri/Documents/WebAgentsreleased.pdf [Retrieved 03/03/2014].
DAISIE European invasive">Invasive Alien species">Species Gateway (2013) Eupatorium adenophorum. Available: http://www.europe-aliens.org/speciesFactsheet.do?speciesId=22615 [Retrieved 02/01/2013].
Muniappan R, Raman A, Reddy GVP (2009) Ageratina adenophora (Sprengel) King and Robinson (Asteraceae). In: Muniappan R, Reddy GVP, Raman A (eds) Biological Control of Tropical Weeds using Arthropods. Cambridge University Press, Cambridge, pp. 63-73.
Osorio VEM, de la Torre WW, Land EO, Silva L, Fernandes FM (2008) Ageratina adenophora (Spreng.) R. M. King & H. Rob. In: Silva L, Land EO, Luengo JLR (eds) Flora e fauna terrestre invasora na Macaronésia. Top 100 nos Açores, Madeira e Canárias. Arena, Ponta Delgada, pp. 201-204.
Smit JT (2006) The Tephritidae (Diptera) of the Madeiran archipelago, Portugal. Instrumenta Biodiversitatis VII: 243-258.
Wan F, Liu W, Guo J, Qiang S, Li B, Wang J, Yang G, Niu H, Gui F, Huang W, Jiang Z, Wang W (2010) Invasive mechanism and control strategy of Ageratina adenophora (Sprengel). Science China. Life Sciences 53(11): 1291-1298.