Herbicide control of summer-active perennial weeds in southern Australia

Perennial weeds are problematic to control due to the presence of both a seedbank and a rootbank. In addition, summer active perennial weeds generally require herbicides to be applied under hot, dry conditions, which are not conducive to good herbicide uptake and translocation. Applying herbicides under more favourable conditions in late summer or early autumn may lead to increased herbicide efficacy. Field experiments were conducted on silverleaf nightshade (Solanum elaeagnifolium) and prairie ground cherry (Physalis viscosa) investigating the effect of herbicide application time upon rootbank dynamics. The silverleaf nightshade rootbank was most effectively controlled when herbicides were applied in autumn prior to the weeds beginning senescence while the prairie ground cherry rhizomes were controlled with herbicides applied in either summer or autumn. These results have significant implications for developing appropriate management packages for these weeds to achieve long term control. Similar approaches could be applied to other intractable perennial weeds