EPPO Platform
on PRAs

EPPO PRA on Amaranthus tuberculatus


Amaranthus tuberculatus presents a high phytosanitary risk for the endangered area with low uncertainty. 

The likelihood of new introductions via bird feed is very high with a high uncertainty. The likelihood of new introductions to the EPPO region occurring via grain of soybean (Glycine max), haricot bean (Phaseolus vulgaris), sorghum (Sorghum bicolor) and maize (Zea mays) is high with a moderate uncertainty. For seeds of beetroot (Beta vulgaris), G. max, cotton (Gossypium hirsutum)alfalfa (Medicago sativa), P. vulgaris, S. bicolor and Z. mays, the likelihood of new introductions is moderate with moderate uncertainty. Entry into the EPPO region via seed mixtures and native seeds is moderate with a high uncertainty. 

Within the EPPO region, currently the species mostly grows in ruderal habitats and along river systems, and to a lesser extent in agricultural environments. A. tuberculatus is capable of invading many summer crops in particular late sowing crops like maize and soybean. The high frequency of maize and soybean in the crop rotation system in many EPPO countries is a factor that may facilitate the establishment of A. tuberculatus once the field has become contaminated. The likelihood of further establishment outdoors is very high with a low uncertainty. Establishment in protected conditions is medium with a high uncertainty. Protected conditions, such as in nurseries and polytunnels, may offer appropriate conditions for the development of the pest. The potential for spread within the EPPO region is very high with a moderate uncertainty. A. tuberculatus can spread both naturally and via human-assisted spread. Seeds of A. tuberculatus can be moved through agricultural machinery and products (e.g. grains, seeds) within the EPPO region. 

The impacts of A. tuberculatus in North America are primarily the reduction of crop yields and increased management costs. The EWG considered the potential socio-economic impacts in the EPPO region will be high with a moderate uncertainty. 

A. tuberculatus is difficult to manage because of the species ability to produce large volumes of seeds and build up a persistant seed bank. This species has already been shown to easily develop resistance to various herbicide mode of actions in North America. The EWG considered that early detection and rapid responses are critical to avoid further spread and impact of A. tuberculatus


  • Amaranthus tuberculatus


Type File Size
Pest Risk Analysis Download 3,74MB

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