Flupropanate – in vitro pasture species susceptibilities

Flupropanate, a soil-active herbicide that inhibits lipid bio-synthesis, has become available in New Zealand for the selective control of the stipoid grasses Nassella neesiana and N. trichotoma in pasture. In commercial spray operations and field trials, the selectivity of the herbicide has been extremely variable. As a first step towards identifying pasture species that could be sown following application of the herbicide, the in vitro dose-response of 33 species and cultivars (grasses and dicotyledons) was determined. Ranking the cultivars based on the slopes of linear regressions fitted to their radicle lengths (relative to untreated control) against the logarithm of flupropanate rate, suggested that ryegrass and Nassella spp. are among the most sensitive whilst plantain, chicory, and some legumes including lucerne are relatively tolerant. The rankings from this study will be subjected to validation in a field trial using a subset of the species.