Evaluation of glyphosate sensitivity of several non-target wild plant species compared to crop species

Field margins represent an important part of agriculture landscape since they are the most abundant habitat for wild plant species and important corridors for migration for agriculture fauna. However these field margins are directly adjacent to threaded crop fields and therefore highly affected due to herbicide spray drift or surface runoff. This leads to direct effects on wild plants as changes in plant diversity, abundance and community composition. Furthermore indirect effects on invertebrates and wildlife can occur due to effects on wild plants. Therefore it is implicitly important to preserve wild plant abundance and diversity in agricultural landscape. To approve a new pesticide on the market it has to be evaluated according to the Plant Protection Product directive (Council Directive 91/414/EEC). According to this directive only effects on crop plants are assessed for herbicide risk assessment. Effect data for non-target plants are not required. However recent literature outlined that wild plants show a hundredfold higher sensitivity to glyphosate and dicamba compared to crop species. It was pointed out that many plant families which are common in agricultural field margins are not included in tests however they react sensitive to herbicide application. At the moment the Guidance Document on Terrestrial Ecotoxicology is under revision and so it needs to be analysed how effectual the current risk assessment for non-target plants is. Several sensitivity data for non-target plants are already available for the substances glyphosat and dicamba and the aim of this master thesis is to collect sensitivity data for non-target plants which have not been tested yet for the substance glyphosat.

To do this I will conduct a 28 days vegetative vigour test based on the OECD Guideline 227 (Terrestrial Plant Test: Vegetative Vigour Test) with 13 wild plant species and two crop plants spreya with Roundup. Dry biomass of plants is acting as endpoint used to calculate EC50’s. From these effect concentrations I will receive a species sensitivity distribution and consequential a HC5 value (hazardous concentration affecting 5% of the plant species).


Julia Brack

Dr. Carsten Brühl