Control of Annual Weeds in Container Grown Nursery Stock1

Abstract

Abstract Seven herbicides were evaluated for their safety and efficacy on 5 species of container grown nursery stock. During both growing seasons all materials except isopropyl-m-chlorocarbanilate [chlorpropham] at 2.2 and 8.9 kg/ha, chlorpropham at 2.2 and 8.9 kg/ha + P-chlorophenyl-N-methylcarbamate [PPG-124] at 0.4 and 1.7 kg/ha, resp., and N,N-dimethyl 2,2-diphenylacetamide [diphenamid] at 5.6 kg/ha gave satisfactory long season (163 days) broadleaf weed control. Long season grass weed control in nursery containers was achieved both years with 2,6-dichlorobenzonitrile (dichlobenil) at 13.4 kg/ha, α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin) at 2.2 and 8.9 kg/ha, S-ethyl dipropylthiocarbamate (EPTC) at 5.6 and 22.4 kg/ha, chlorpropham + PPG-124 at 8.9 + 1.7 kg/ha and diphenamid at 22.4 kg/ha. Both azalea species employed in the test exhibited severe chlorosis, necrosis, and stunting when dichlobenil at 13.4 kg/ha and EPTC at 22.4 kg/ha were employed. Japanese holly and ‘Sasanqua’ camellias were severely injured by dichlobenil at 13.4 kg/ha, while ‘Hetzi’ juniper was tolerant to all herbicides at all rates employed.