Response of Two Container-grown Ilex Species to Preemergence Herbicides

Abstract

Abstract Container-grown Chinese holly (Ilex cornuta Lindl. Paxt. cv. Burfordii) and Japanese holly (Ilex crenata Thunb. cv. Helleri) were treated with 6 preemergence herbicides: alachlor [2-chloro-2’,6’-diethyl-N-(methoxymethyl) acetanilide], napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide], oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide), and oxadiazon [2-tert-butyl-4(2,4-dichloro-5-isopropoxyphenyl)-Δ2-1,3,4-oxadiazolin-5-one] at 2.2, 4.5, 9.0, and 17.9 kg/ha; oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene] at 1.1, 2.2, 4.5, and 9.0 kg/ha; and prodiamine [2,4-dinitro-N3,N3-dipropyl-6-(trifluoromethyl)-1,3-benzenediamine] at 4.5, 9.0, and 13.4 kg/ha. All herbicides at all rates significantly reduced the number and weight of weeds as compared to unweeded checks but higher rates were more effective. Lower rates of herbicides failed to control Pennsylvania bittercress, yellow wood sorrel, and purple nutsedge. Oryzalin at 9.0 and 17.9 kg/ha was phytotoxic to both hollies. Generally, Chinese holly was more tolerant to herbicides than Japanese holly. Oryzalin was most phytotoxic to Chinese holly and substantially reduced the growth and marketability of the plants. Oxyfluorfen at 9.0 kg/ha severely retarded the growth of Japanese holly.