Modeling the Effect of Washing Hydraulic Fluid Spills on a Hybrid Bermudagrass Green.

Strategies for mitigating turf injury from hydraulic fluid (HF) spills are lacking.  Research was conducted in 2014 to determine if washing HF spills with water reduced injury area (IA) on a hybrid bermudagrass (Cynodon dactylon [L.] Pers. var. dactylon x C. transvaalensis Burt-Davy var. ‘Tifeagle') putting green.  If washing reduces IA then turf injury should heal faster.  To test this hypothesis a split-plot field experiment was conducted.  Three mL hot (80°C) petroleum HF (PHO), vegetable HF (VHO), or synthetic HF (SHO) were applied to turf in a single spot.  After 75 min spills were washed with water or left unwashed.  Resulting IA was determined over 38 d using image analysis.  Washing reduced IA for SHO and PHO (p = 0.0198) but not for VHO.  Injury area for SHO averaged 2.2 (washed) and 12.6 cm² (unwashed) at 38 DAT (p = < 0.0001).  For PHO it averaged 39.9 and 47.1 (p = 0.0306) and for VHO it averaged 32.1 and 32.5 (p = 0.7678).  Fitting a hyperbolic-linear model to IA data over time produced best-fit regression lines for all HF.  Modeling indicated the rate of change in IA expansion and contraction differed between SHO treatments (p = < 0.0001).  Washing slowed the initial rate of expansion (p = 0.0525) and accelerated the rate of contraction (p = < 0.0001).  This was not observed for non-polar HF.   Predicted healing time was reduced to 65 d (SHO washed) compared to > 120 d (SHO unwashed).  Predicted healing for non-polar HF was > 200 d regardless of treatment.  Washing SHO with water reduced IA and hastened turf recovery confirming the hypothesis.  This was attributed to SHO being soluble in water.  Washing non-polar HF with water was not an effective turf injury mitigation strategy.