In some regions, contamination of organic crops with weeds containing tropane alkaloids such as Jimson Weed and Black Henbane is increasing. Concerned crops are mainly corn, millet, buckwheat and sunflowers. Tropane alkaloids are toxic to warm-blooded animals. Small amounts of these substances can lead to contamination of an entire crop, making it no longer marketable. The new guide picks up the problem that still is largely unrecognized in practice and provides recommendations for control of the weeds.