Research Station Agroscope Changins-Wädenswil, CH-1260-Nyon 1

Invasive plants: agricultural aspects

In Switzerland also, alien plant invaders can threaten biodiversity. The impacts of these invasive plants on agriculture can very according to species. In fact, most of them are not directly related to agriculture; but some species, such as ragweed (A. artemisiifolia) or narrow-leaved ragwort (S. inaequidens), can also colonise and threaten arable land. On the other hand, some new non-native species, such as velvetleaf (A. theophrasti), are potent noxious agricultural weeds that do not threaten natural habitats and biodiversity. Even native plants are mentioned as locally becoming invasives (S. aquaticus and S. jacobaea). This paper clarifies some definitions about the notions of “weed” and “invasive plant”. It describes some examples of alien species presently important for Switzerland as invaders and their relationship, very variable, to agriculture. It also discusses the collaborations now needed between agriculture and biodiversity conservation.

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