Southern Redcedar and Southern Magnolia Wood Chip Mulches for Weed Suppression in Containerized Woody Ornamentals

Abstract

Wood chip mulches from southern redcedar (Juniperus silicicola) and southern magnolia (Magnolia grandiflora) were evaluated for their effectiveness in weed control in nursery containers. In greenhouse tests, southern redcedar and southern magnolia wood chip mulches significantly inhibited the germination of redroot pigweed (Amaranthus retroflexus) and large crabgrass (Digitaria sanguinalis). In a field trial, nursery containers with ‘Carolina Beauty’ crape myrtle plants (Lagerstroemia indica) were sown with large crabgrass and redroot pigweed seeds, mulched with southern redcedar or southern magnolia wood chips, and compared with plants without mulch and plants treated with a mixture of isoxaben and trifluralin (Snapshot). Wood chips from both southern redcedar and southern magnolia were as effective as a mixture of isoxaben and trifluralin in suppressing weed growth in nursery containers. The wood chip mulches had no inhibitory effect on the growth of crape myrtle plants. In a similar, longer-term field trial using containerized dogwood (Cornus florida) plants sown with large crabgrass and redroot pigweed, the southern redcedar wood chip mulch was most effective in weed suppression when used in combination with a low dose of the chemical herbicide.