Control of Oaks (Quercusspp.) and Associated Woody Species on Rangeland with Tebuthiuron

Abstract

Aerial applications of 20% tebuthiuron {N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N-dimethylurea} pellets at 2.2 kg/ha (ai) in the spring effectively controlled post oak (Quercus stellataWangenh.), blackjack oak (Q. marilandicaMuenchh.), water oak (Q. nigraL.), yaupon (Ilex vomitoriaAit.), winged elm (Ulmus alataMichx.), downy hawthorn (Crataegus mollisScheele), gum bumelia [Bumelia lanuginosa(Michx.) Pers.], and willow baccharis (Baccharis salicinaTorr. & Gray) in the Post Oak Savannah of Texas. Tree huckleberry (Vaccinium arboreumMarsh.), black hickory (Carya texanaBuckl.), honeylocust (Gleditsia triachanthosL.) and cedar elm (Ulmus crassifoliaNutt.) were partially controlled by 2.2 kg/ha of tebuthiuron. Canopies of buckbrush (Symphoricarpos orbiculatusMoench), southern dewberry (Rubus trivialisMichx.), American beautyberry (Callicarpa americanaL.), and persimmon (Diospyros virginianaL.) were reduced for about two growing seasons after which the woody species recovered. American beautyberry appeared to increase in abundance by the third growing season after control of the other woody species. Honey mesquite [Prosopis juliflora(Swartz) DC. var.glandulosa(Torr.) Cockerell], eastern redcedar (Juniperus virginianaL.), and Texas persimmon (Diospyros texanaScheele) were not controlled by tebuthiuron at 2.2 or 4.4 kg/ha, and saw greenbrier (Similax bona-noxL.) and peppervine [Ampelopsis arborea(L.) Koehne] apparently increased following application of tebuthiuron.