Effects of Trinexapac‐Ethyl, Surfactant, and Nitrogen Fertilization on Bermudagrass Water Use

Abstract

Persisting drought conditions in California are limiting water allocation for golf course irrigation. A study was conducted at the University of California, Riverside to determine if products including trinexapac‐ethyl (TE), a surfactant (Revolution), and nitrogen (N) fertilizer [Gro‐Power (5–3–1); SeaBlend (12–4–5) + StressRX (6–0–2) + XP Extra Protection (5–0–0); YaraLiva (15.5–0–0); Turf Royale (21–7–14); each applied at 25 g N m−2 yr−1) could enhance quality of ‘Princess 77’ bermudagrass (Cynodon dactylon L. Pers.) irrigated at 53 or 92% turfgrass evapotranspiration (ETc) under fairway conditions. Product and irrigation treatments were applied from May through October 2016 and 2017. Every 2 wk, plots were evaluated for visual quality, normalized difference vegetation index, soil volumetric water content using time domain reflectometry, and percent green cover using digital image analysis. Root samples were collected in November of both years, and fall color retention and spring green‐up were assessed using digital image analysis. At 92% ETc replacement, visual quality was highest in plots that received TE and surfactant. Although no differences were found among fertilizer treatments, fertilization alone was able to sustain visual quality at a minimally acceptable level at 92% ETc. Surfactant had the greatest positive effect on turf irrigated at 53% ETc, whereas TE did not improve visual quality on the same plots. Overall, results indicate that regular applications of either Revolution surfactant or SeaBlend + StressRX + XP Extra Protection can sustain bermudagrass visual quality at 53% ETc.Core Ideas Surfactants could substantially reduce irrigation requirements on bermudagrass turf. Fertilizers with low burning potential should be used in case of water restrictions. Deficit irrigation results in loss of quality during the summer months. Severe drought has an effect on bermudagrass root morphology.