Effects of Seasonal Trinexapac-Ethyl Application on Warm-season Turfgrass Colour, Quality and Spring Green-up under Mediterranean Environment

Applications of the plant growth regulator trinexapacethyl (TE) [4-(cyclopropyl-alpha-hydroxymethylene)-3,5-dioxocyclohexane carboxylic acid ethylester] can enhance turfgrass colour, quality, and delay winter dormancy of warm-season turfgrass species. The objective of this study was to: study the effects of seasonal TE application on turfgrass duality, colour, fall colour retention and spring green-up of warm-season turfgrass species: Cynodon dactylon (L.) Pers., Buchloe dactyloides Engelm., Zoysia japonica Steudel, Paspalum notatum (Flugge), Paspalum vaginatum Swartz, and Eremochloa ophiurioides (Munro) Hack in the Mediterranean region. Applications of TE to the nineteen seeded-type cultivars were made to fully established turf plots at a 0.38 kg active ingredient (a.i.) ha(-1) rate in summer or fall. Application schedule included a single application, followed by zero or one sequential application at 4-wk. Overall, TE enhanced turfgrass colour and quality in summer. The late season TE application decreased the quality, fall green colour retention up to 3-wk and delayed spring green-up by 15 d to 30 d. Results support the use of sequential application of TE for improved turfgrass colour and quality in summer. Reduced early fall TE applications should be examined to extend fall colour retention in future studies.