Application of a standardized bioassay to estimate the phytotoxic effects of frequently used herbicides on non-target plants

Within the framework of the provisional German guideline "Testing of herbic ide phytotoxicity to succeeding crops", bioassays for the assessment of the residue behaviour of phytotoxic substances have been standardised. The met hod has been modified so as to facilitate the assessment of the phytotoxic effects of pesticides on non-target plants as well. This includes which and how many species should be covered and which endpoints (e. g., seed germin ation, percentage of germination and early seedling growth) should be selec ted. The experimental design is of marked influence on the results of bioas says that can be deemed significantly different. Results are given to show the vertical and horizontal comparison of dose-response curves for 5 freque ntly used herbicides (glyphosate, isoproturon, chlorotoluron, metamitron, a nd pendimethalin) and 15 test species that represent specific plant familie s. Recommendations are given for the assessment of effects of a potential p hytotoxic compound on the test organism.