Activated carbon seed technologies provide some protection to seedlings from the effects of post‐emergent herbicides

Abstract

Invasive plant species create barriers to native species' reestablishment after land degradation. Postemergent herbicides are preferred (over preemergent) for use in restoration as they are not expected to affect native seeds. However, recent studies found that postemergent herbicides can persist in soils and reduce native species' seed germination and seedling emergence. Activated carbon seed enhancement technologies (SETs) can protect seeds from preemergent herbicides but are untested with postemergent herbicides. We explored the effects of two postemergent herbicides, Roundup and Fusilade, on seedling emergence and health of five species native to Banksia Woodlands of Western Australia. We investigated if activated carbon SETs protect seeds and seedlings from any negative effects caused by herbicide application. A randomized block design was used, and herbicide applied to the soil after seeds (nonenhanced and enhanced with activated carbon SETs) were sown under field conditions. Roundup considerably reduced seedling emergence of Acacia pulchella, Banksia menziesii, and Eucalyptus todtiana, whereas Fusilade did not negatively affect emergence. Both herbicides considerably reduced seedling health for A. pulchella, B. menziesii, and E. todtiana. Activated carbon increased A. manglesii emergence in all treatments. Activated carbon also notably increased the percentage of healthy A. pulchella, B. menziesii, and E. todtiana seedlings in herbicide treatments, indicating that activated carbon can provide protection from postemergent herbicides applied to the soil before seedling emergence. Roundup and Fusilade should not be used in restoration when soil seed banks are the source of native seeds, and a time lag is required when direct seeding after herbicide application.