Problematic weed species in organic arable agriculture around the Baltic Sea - an expert database

Summary

Weeds are a perpetual challenge in Organic agriculture. However, they serve multiple ecosystem services and a low competitive weed cover can be tolerated. Adding to
this, is the fact that only a few species prove problematic for both the crop and the farmer. The international PRODIVA project researches the effect of crop diversity strategies on the diversity of weed communities, hypothesizing that by increasing the weed diversity, the development of problematic weeds will mitigated. A preparatory
study was conducted to list the most problematic weed species in spring sown cereals in the countries involved with PRODIVA. For this a literature review was conducted in
all participating countries, collecting local sources including grey literature. This was combined with the opinion of local extension services and other weed experts. From this a list of 10 most problematic weeds was deducted for each country. We found both annual and perennial species to be mentioned as problematic. A majority of the
more problematic species were shared between countries, such as Cirsium arvensis, Elitrigia repens and Chenopodium album. Still, all countries revealed to have individual
weed challenges as well. These findings are published as a folder that will be available to local stakeholders.