Efficacy of Bio-based Liquid Mulch on Weed Suppression and Water Conservation in Container Nursery Production1

Abstract

Abstract To assess the effectiveness of bio-based liquid mulch at different application rates and binder loading types for weed suppression and evaporation reduction in container nursery production, a study was conducted outdoors in the summer of 2015 in Ontario, Canada. Three application rates [0.5 1.25, or 2.0 kg·m−2 (0.20 lb·ft−2)] and two binder loading types (AMP753 with 3.5% binder loading or AMP153 with 7% binder loading) of the liquid mulch were used in the trial. The evaporation rates (ER) from the container growing substrate were quantified daily for three 7-day cycles. All mulched treatments reduced total ERs starting from the second cycle compared to the no-mulch control, with the exception of the treatment binder loading type 3.5% with 0.5 kg·m−2 mulch. All mulched treatments had an equivalent effect at reducing weed numbers compared to the control. The 1.25 and 2.0 kg·m−2 rates were more effective for weed control than the low application rate (0.5 kg·m−2) and there were no differences between binder loading types. No negative effects on overall plant health, flower or branch number, total aboveground biomass, leaf area, or plant growth index were observed on Hydrangea paniculata ‘Jane' from the applied mulch. A major shortcoming with the product as tested was that it dried and shrunk within a couple of days of application. This caused a gap of approximately 10 to15 mm (0.39-0.59 inch) between the wall of the pots and the actual dried mulch. The 1.25 kg·m−2 rate of either binder loading type (3.5% or 7%) could be recommended if the shrinking issue of this mulch could be resolved. Index words: Evaporation, witchgrass, Powell's amaranth, green foxtail, little lime hardy hydrangea. Chemicals used in this study: Bio-based Liquid Mulch. Species used in this study: witchgrass (Panicum capillare L.), Powell's amaranth (Amaranthus powellii S. Watson), green foxtail (Setaria viridis (L.) Beauv.), common groundsel (Senecio vulgaris L.), little lime hardyhydrangea (Hydrangea paniculata L. ‘Jane').