Effect of Synthetic Hydraulic Fluid On Warm Season Turfgrass.

Hydraulic oil (HO) injures turf.  Synthetic hydraulic fluid (SF) was compared to HO for injury potential.  Effect of volume and temperature on injury area, percent necrosis, and healing time was studied on hybrid bermudagrass (Cynodon dactylon L. [Pers.] x C. transvaalensis Burtt-Davey) and seashore paspalum (Paspalum vaginatum O. Swartz).  Treating container-grown ‘Tifeagle' with SF at 1.85 mL cm^-2 resulted in 0% necrosis 10 DAT while HO resulted in 100% necrosis.  Treating turf in situ with 1 mL SF at 50°C caused 2 cm² injury with 20% necrosis.  At 70°C it caused 2 cm² injury with 63% necrosis.  The same effects were observed on turf treated with water, suggesting hot fluids injure turf.  When applied at 50°C or 70°C HO caused 12 cm² injury with > 90% necrosis, dispelling the myth that HO must be hot to injure turf.  Increasing the volume of SF to 5 mL at 50°C increased injury area and necrosis to 10 cm² and > 80%.  Increasing the volume of HO to 5 mL at 50°C increased the injury area to 30 cm² with > 90% necrosis.   Spilling 20 mL SF at ambient temperature caused 70 cm² injury with 17% necrosis healing in 15-30 d.  Twenty mL HO caused 184 cm² injury with 80-100% necrosis healing in > 30 d.  For given spill volumes and temperatures SF caused smaller injuries with less necrosis and shorter healing times.  It may pose less injury potential than HO if leaked from turf equipment.