Seasonal Growth Influences Recovery from Hydraulic Oil Injury on a Bermudagrass Green.

Vegetable hydraulic oil (VHO) is reported to be less toxic to turf than petroleum hydraulic oil (PHO).  If true then recovery from VHO injury should be faster.  Research initiated in December, 2013 in Fort Myers, FL sought to determine recovery times for injury from VHO and PHO on a Tifeagle hybrid bermudagrass (Cynodon dactylon L. [Pers.] var. dactylon x C. transvaalensis Burtt-Davy) green.  Three mL PHO or VHO was dripped onto turf in a single spot from a height of 1 cm, and resulting injury area (IA) was measured over time.  The IA from PHO expanded to 54 cm² at 36 d contracting to 8.4 cm² by 110 d.  Injury from VHO expanded to 40 cm² at 10 d contracting to 7.0 cm² by 110 d.  Recovery times for both oils were similar, as IA did not differ at 68 d (p = 0.1146), 81 d (p = 0.457) or 110 d (p = 0.634).  When repeated in March, 2014, IA from PHO expanded to 41 cm² at 15 d contracting to 17 cm² at 79 d; for VHO it expanded to 33 cm² at 4 d, contracting to 9 cm² by 79 d.  This time injury from VHO recovered faster than injury from PHO; IA differed at 8 d (p = 0.0197) continuing through 79 d (p = 0.008).  Experiments also differed; March treatment totals were less than December totals at 36 d (p = 0.003) 59 d (p = < 0.001), and 79 d (p = < 0.001).  Injury from VHO healed faster than injury from PHO when turf growth was active.  Seasonal growth appeared to influence recovery from spills of hydraulic oil on a hybrid bermudagrass green.