Soil Type and Rooting Depth Affect Hybrid Bermudagrass Injury with Preemergence Herbicides

Applications of preemergence (PRE) herbicides can injure hybrid bermudagrass [C. dactylon (L.) Pers. x C. transvaalensis Burtt-Davy]. Research was conducted to determine the effects of soil texture and rooting depth on hybrid bermudagrass injury with two PR E herbicides. Washed 'Tifway' hybrid bermudagrass sod was established in mini-rhizotrons. Treatments included the factorial combination of two soils (sand, silt loam), four herbicides (indaziflam at 35, 52.5, and 70 g ha(-1) and prodiamine at 840 g ha(-1)), and three rooting depths (5, 10, and 15 cm). Averaged across both soils, foliar injury and reductions in root-length density were greatest at rooting depths <= 15 cm. In a sand rootzone with no organic matter, significant foliar injury (23 to 48%) was observed with indaziflam; however, foliar injury with prodiamine measured <= 7%. In the silt loam rootzone, injury measured 0 to 17% with all herbicides. Data indicate that soil type and rooting depth affect hybrid bermudagrass injury with indaziflam; however, additional research is needed to determine if these glasshouse responses will be similar under field conditions. Differential effects on root function, as well as soil biological, chemical, and physical properties may also affect injury potential with indaziflam and prodiamine applications in sand rootzones. Additional research is needed to explore the effects of indaziflam and prodiamine on hybrid bermudagrass root physiological function in further detail.