Influence of herbicides on rangeland vegetation of the Rio Grande Plain
1971
Buckley, Philip Elanson
The Rio Grande Plain resource area of Texas consists of some 20 million acres, 17 millions of which are rangeland. Over 90% of the rangeland supports 20% or greater brush cover including Opuntia spp. (pricklypear). This area is reported as having been largely grassland on which woody species encroachment took place with the intensification of the livestock industry and reduction of fires. The experimental herbicides, hexaflurate (potassium hexafluoroarsenate) at 1, 2 and 4 lb/A ground application and 2 lb/A aerial application and 2,4,5-T (2,4, 5-Trichlorophenoxacetic acid) at 2 lb/A ground application, were evaluated to relative to efficacy as vegetation management tools on three typical soil types of this region. Hexaflurate was found to be an effective herbicide for the control of pricklypear. Aerial application 2 lb/A was equal or superior to ground application at the same rate. Greater control was achieved at the 4 lb/A rate on some plots. Hexaflurate at 2 lb/A aerial application was equal or superior to 2,4,5-T on all plots treated and superior on all plots of greater than 2 year duration. As pricklypear density decreased following treatment, grass production generally increased. Grass production increased on most hexaflurate treated plots with increase in time following treatments. Fresh mulch accumulation was generally related to grass production of the preceding year. Hexaflurate appeared to be an effective tool to reduce pricklypear stands and encourage increased grass production on the rolling hardland and red sandy loam range sites. Although it reduced pricklypear density on the saline clay flat range site, increased herbage production did not occur.
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