Effects of Picloram and Tebuthiuron Pellets on Sand Shinnery Oak Communities

Abstract

Picloram and tebuthiuron pellets (10% a.e.) were broadcast onto fair to low-good condition range supporting sand shinnery oak in west Texas. The Sands range site has traditionally been overgrazed and soils are very susceptible to wind erosion. Picloram at 7 kg/ha (a.i) resulted in excessive oak control in 1971. In 1973, 1975, and 1976, herbage yields on the treated plots were the same as on untreated plots. Herbicide application on this site dramatically changed species composition. Applications of tebuthiuron at 1 kg/ha (a.i.), in late spring and winter killed most of the oak. Grass responses to this herbicide were good, but at rates higher than 1 kg/ha some of the better forages were killed allowing false buffalograss, an undesirable annual, to become dominant. Picloram pellets, at 3, 5, and 7 kg/ha, killed all the oak. However, picloram at 1 kg/ha only partially controlled the oak. Picloram pellets were not as detrimental to the plant community as the tebuthiuron. One kg/ha of tebuthiuron or 2 kg/ha of picloram totally controlled the sand shinnery oak on the Brownfield soil.