Influence of hexazinone on pensacola bahiagrass growth and crude protein content
Bahiagrass (Paspalum notatum Flüggé) is the most widely used introduced forage in Florida, due to its persistence and productivity on low fertility soils. Hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H,3H)-dione], the only herbicide labeled for small and giant smutgrass [Sporobolus indicus (L.) R. Br. and S. indicus (L.) R. Br. var. pyramidalis (P. Beauv.) Veldkamp] control in pastures, may impact bahiagrass biomass production and crude protein (CP) content. Field experiments were conducted at two locations in 2005 and 2006 to determine the impact of hexazinone on pure stands of ‘Pensacola’ bahiagrass biomass accumulation and CP content. Hexazinone was applied at 0, 0.28, 0.56, 1.12 and 2.24 kg ai ha–1 in July of each year to actively growing bahiagrass. Hexazinone was observed to reduce bahiagrass overall biomass accumulation, but the severity of bahiagrass injury varied depending on year and location. Generally, little or no reduction in biomass accumulation occurred from hexazinone applied at 0.28 or 0.56 kg ha–1. However, hexazinone applied at the recommended use rate of 1.12 kg ha–1 resulted in 9 to 38% less dry matter accumulation relative to the untreated 84 d after treatment (DAT). At Gainesville, hexazinone did not consistently affect CP content of bahiagrass in either year. At the Ona location, CP generally increased with the application of hexazinone in both years. Crude protein was observed to increase by approximately 16 to 21% when hexazinone was applied at 1.12 kg ha–1. These data show that hexazinone application results in reduced bahiagrass production, without reducing crude protein content.