Assessing weed risk assessments

Authorities often rely on weed risk assessments (WRAs) to determine the invasive potential when considering a non-native plant species for introduction. The parameters and limits of the models used differ between countries, and in this study, researchers used 40 species of crops and invasive species to compare the WRAs used in the United States and Australia. Both models failed to distinguish weeds from crops, judging major crops like barley, rice, canola, and alfalfa to be high-risk. In one model, cereal rye scored higher than kudzu, a prodigious invader in the Southeastern U.S. The results reveal serious weaknesses in the WRAs and recommend caution in applying these models. The authors suggest additional screening such as field testing as a complementary method for assessing invasion risk.