Abstract

The root system of containerized nursery stock may become undesirably coiled or matted on the outer surface of the media. Various copper formulations painted on the interior of the container surface have been shown to control undesirable root growth in a few species. We tested a commercial formulation of 100 g/l copper hydroxide in a flowable latex paint formulation (SpinOut™) on 41 tree, shrub, and herbaceous species. Plants were grown 4 months in 7.5×7.5×15cm containers, either treated or untreated. Root density was evaluated on a scale of 1 to 5 (no roots on the surface to heavy rooting). Analysis showed treated containers prevented roots from growing on the media surface in all species tested except Magnolia liliiflora `Jane', Buxus sempervirens `Vardar Valley', and Taxus × media `Hicksii', where control of surface rooting was significant but moderate. Copper paint did not inhibit growth of stolons or rhizomes, which morphologically are stem structures. No visual signs of copper toxicity were observed, nor were there any differences in shoot growth.