Pyrrolizidine alkaloid-containing weeds in medical and herb plant cultures - Distribution and danger of contamination in crop products in Germany

Abstract

During the vegetation periods of 2015 to 2017 the weed flora of six important herb cultures were surveyed in context of a cooperation funded by the BMEL and the Fachagentur Nachwachsende Rohstoffe e.V. (FNR). The choice of the crop species was influenced by the size of the area of cultivation as well as the already known frequency and amount of contamination by pyrrolizidine alkaloids (PA).
The result shows, that in Germany only a small number of species is responsible for the contamination. Nine of the 164 identified weed species are known PA plants. The quantitative main portion is shared by the genera Senecio and Myosotis, who belong to the Asteraceae and Boraginaceae family respectively. The most important weed is Senecio vulgaris, which takes the first position by means of frequency as well as total content of PA.
The survey of the fields shows, that the distribution and amount is highly dependent on the cultivation methods and the local conditions, as it would be suspected. More open or lower cultures are significantly more vulnerable than denser and closed crops.
The survey data as well as further information on weeds are meant to facilitate the identification and control of PA species. They are gathered, anonymised and made available to authorities, co-financing companies and organizations in form of a database.