Plant growth regulator effects on winter hardiness of annual bluegrass putting green turf

Cold deacclimation sensitivity has been cited as an important factor associated with winterkill susceptibility of annual bluegrass (Poa annua L.). Increased potential for this species attributed to higher metabolic activities in response warm winter temperatures. We hypothesized that using plant growth regulators inhibit turfgrass and metabolism during months could potentially suppress premature increase survival bluegrass. The specific objectives study were examine the effects varying rates autumn-applied trinexapac-ethyl (TE) prohexadione-Ca (PC) on hardiness spring recovery putting green. was conducted over winters 2015–2016 2016–2017. Treatments included untreated control four TE (0.05, 0.10, 0.2, 0.4 kg a.i. ha–1) PC (0.06, 0.12, 0.25, 0.50 ha–1). Freezing tolerance assessed based controlled freeze tests estimate lethal temperature resulting 50% regrowth (LT50). General health also visual turf quality normalized difference vegetation index (NDVI). Late-autumn PGR applications impacted freezing Year 1, but no treatment detected 2. Plant regulator treated turf, pooled chemicals rates, exhibited lower (Year 1), quality, NDVI (Years 1 2) compared particularly at application rates. By end May both years, all treatments recovered same levels.