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EPPO PRA for Amaranthus palmeri


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

The likelihood of new introductions to the EPPO region occurring via bird feed is very high with a high uncertainty. The likelihood of new introductions to the EPPO region occurring via grain of peanut Arachis hypogaea, soybean (Glycine max), sunflower (Helianthus annuus), rice (Oryza sativa), sorghum (Sorghum bicolor) and maize (Zea mays) is high with a moderate uncertainty. For seeds of Glycine max, Gossypium hirsutum, Helianthus annuus, Oryza sativa, Sorghum bicolor and Zea mays, the likelihood of new introductions is moderate with moderate uncertainty. Entry into the EPPO region via seed mixtures and single species native seed packets is moderate with a high uncertainty. 

Within the EPPO region, the species mostly grows in managed habitats such as ruderal and agricultural environments. A. palmeri 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. palmeri once the field has become contaminated. The likelihood of further establishment outdoors is very high with low uncertainty. Establishment in protected conditions is moderate with 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 low uncertainty. A. palmeri can spread both naturally and via human assisted spread. Seeds of A. palmeri can be moved through agricultural machinery and plant products (e.g. grains, seeds) within the EPPO region. 

The impacts of A. palmeri 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. palmeri is difficult to manage because it can 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. palmeri. The EWG recommended that a weed management strategy should to be developed for the EPPO region as a priority due to the recent increase in the reported spread (Catalonia in Spain).


  • Amaranthus palmeri


Type File Size
Pest Risk Analysis Download 4,15MB

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