Eppo region: Italy (found near Trieste on a small site), Switzerland (few sites in southern Alps & Ticino). Africa

Why Pueraria montana var. lobata (kudzu) is thought to originate from Asia. It is known as an invasive plant and damaging weed in south-eastern USA where it has been introduced for ornamental purposes in the 1870s. Its cultivation was then encouraged for forage and soil erosion control, until it was perceived as a weed in the 1950s. In 1998, kudzu was listed as a noxious weed. In Europe, its presence has so far been reported from Switzerland and more recently from Italy. Considering the difficulties caused by this plant species in south-eastern USA, the EPPO Secretariat decided to add it to the Alert List.

Description Climbing, semi-woody, deciduous, perennial vine with large tuberous roots and dark brown stems (up to 20 m long). Herbaceous stems are hairy. Leaves are alternate with 3 leaflets (hairy on both surfaces and up to 15 cm long). Pea-like flowers are pink to purple, highly fragrant and borne in long hanging panicles (10-25 cm long). Flowering is soon followed by the production of brown and hairy pods, each containing 3 to 10 seeds. Vegetative growth can be very rapid (up to 25 cm per day or 18 m per growing season) and plants produce root crowns where nodes contact soil.

Images can be viewed on Internet:

http://www.hear.org/starr/hiplants/images/thumbnails/html/pueraria_montana_var_lobata_thumbnails.htm

Where EPPO Region: Italy (found near Trieste on a small site), Switzerland (few sites in southern Alps & Ticino).

Habitat Forest edges, abandoned fields, roadsides, riparian zones, urban areas and other disturbed habitats. Drought and frost tolerant (only aboveground parts are damaged by frost). Most favourable conditions are 1000 mm precipitation per year, as well as high summer temperatures (above 27°C). Kudzu prefers profound, well-drained loamy soils but is able to establish in less favourable conditions.

Damage Kudzu climbs vigorously and rapidly over other plants including forest trees, forming large impenetrable masses of vegetation. It completely covers the existing vegetation and finally replaces it. In some areas, biodiversity of flora and also fauna is much reduced. Growth of vines along electric or telephone cables can pose problems. In south-eastern USA, it is estimated that over 2.8 million ha are massively overgrown by kudzu. In the forestry sector it is estimated that 340 million USD are lost per year. When including impacts on cultivated plants and urban environments, these losses could reach 500 million USD per year in land productivity and control costs. However, in other areas where P. montana var. lobata has also been introduced such as South and Central America, it is apparently not considered as a damaging plant. It can be noted that kudzu can be used for many different purposes: starch production from roots, several plant parts can be cooked as vegetables or used as medicines, stems can even be transformed into baskets or other braided objects.

Dispersal In USA, spread is essentially ensured by vegetative growth (runners, rhizomes and adventitious roots). Seed production is poor in American conditions. This may be due to the lack of efficient pollinators. However these seeds can contribute to further spread of the plants as they may be dispersed by mammals and birds. Over long distances, dispersal is mainly ensured by human activities (movements of infested soil, trade of plants).

Pathway Plants for planting, soil with living parts (rhizomes, seeds).

Possible risks Control (mechanical, chemical or biological) is difficult and costly. To be effective in the long-term, control measures should ensure complete destruction of the extensive root system, as any remaining root crown may lead to re-infestation. More data would be needed on the potential of establishment of kudzu in Europe, as its seems that this plant prefers rather hot and humid climates. A PRA carried out by the German NPPO suggested that, in Germany, conditions were only suitable for kudzu in one small region (around Bonn and Köln, near the Rhein). However, considering the highly invasive potential of kudzu in parts of USA, it seems desirable to survey kudzu populations in Europe and try to avoid any further introduction and spread.

Source(s) CABI Crop Compendium, 2004.

Clabassi, I.; Tome, A.; Otto, S.; Zanin, G. (2003) Segnalazione di una nuova potenziale pianta infestante: Pueraria montana. Informatore Fitopatologico, 53(9), 30-33.

Schrader, G. (2004) PRA and report of PRA on Pueraria lobata (Kudzu). Unpublished documents.

Invasive plants of the Eastern US. Kudzu written by Britton, Orr and Sun, J. http://www.invasive.org/eastern/biocontrol/25Kudzu.html

INTERNET

Commission Suisse pour la conservation des plantes sauvages. CPS. Liste noire – Watch list.. http://www.cps-skew.ch/francais/liste_noire.htm

Invasive species (US). http://www.invasivespecies.gov/profiles/kudzu.shtml

Plant Conservation Alliance (US). Kudzu. http://www.nps.gov/plants/alien/fact/pulo1.htm

University of Florida, Center for Aquatic and Invasive Plants Aquatic, Wetland and Invasive Plant Particulars and Photographs. Pictures and datasheet. http://aquat1.ifas.ufl.edu/puemon.html & http://aquat1.ifas.ufl.edu/puemon.pdf

USDA National Ressources Conservation Service. Plant Profile. http://plants.usda.gov/cgi_bin/plant_profile.cgi?symbol=PUMOL

The World Conservation Union. Global Invasive Species Database. Pueraria montana var. lobata. http://www.issg.org/database/species/ecology.asp?si=81&fr=1&sts=

EPPO RS 2004/141