Turfgrass areas and golf industry have been under scrutiny for their potential impact on the environment, but more environmentally friendly organic fertilizers are increasingly being used to reduce and replace some inorganic fertilizers. A study was conducted on an 8-year-old ‘Tifeagle’ ultradwarf bermudagrass green mowed daily at 0.125 in. located at the University of Florida’s Fort Lauderdale Research and Education Center, Davie, FL to evaluate the effect organic fertilizers and biostimulants on turfgrass performance of Tifeagle’ bermudagrass green. Treatments included: a) XP Stress Rx (applied at 6 6 fl oz./1000 sq. ft.); b) XP-N Stress Rx (applied at 6 6 fl oz./1000 sq. ft.); XP-N Stress Rx Nautilus NuRelease (applied at 6 6 6 0.35 fl oz./1000 sq. ft.). Initial treatment was applied on June 1, 2023, with subsequent applications every 14 days for a total of nine applications. Data was collected every two weeks until three weeks after final application. Turf quality was measured on a 1-9 scale with 9=dark green dense turf, 1=dead/brown turf, and 6=minimally acceptable turf; Normalized Difference Vegetation Index (NDVI) was assessed using a RapidSCAN CS-45; percent green cover and Dark Green Color Index (DGCI) were assessed through Digital Image Analysis of one image taken per plot; volumetric water content was measured at a 3-inch depth using a time domain reflectance sensor. During the summer turfgrass quality, NDVI and DGCI were affected by treatment applications during five of the rating days. Overall, turfgrass fertilized with XP Stress Rx, XP-N Stress Rx and XP-N Stress Rx Nautilus NuRelease showed a higher quality, NDVI and DGCI compared to the unfertilized. Volumetric water content was affected by treatments only after the first application, and no differences were found thereafter. When temperature dropped, and up to three months after last application, biostimulants had a tremendous effect on ultradwarf bermudagrass health preventing the grass from Curvularia spp. infection and helping turfgrass maintaining quality and functionality through the winter.
