Response of ‘Tifway’ Bermudagrass to Trinexapac-Ethyl and Chelated Iron

Trinexapac-ethyl[4-(cyclopropyl-alpha-hydroxymethy-lene)3,5-dioxo-cyclohexanecarboxylic acid ethylester] plant growth regulator was applied alone or tank-mixed with Fe (sodium ferric diethylenetriamine penta-acetate) to ‘Tifway’ bermudagrass [Cyno-don dactylon (L.) Pers. × C. transvaalensis (Burtt-Davy)] in two studies during 1995 in Guam. These studies were conducted to determine the potential of Fe to mask injury of bermudagrass caused by the plant growth regulator. Treatments consisted of 0.1,0.2, 0.4, and 0.8 kg ha1 of trinexapac-cthyl applied with or without 1.0 kg Fe ha1 iron chelate, in one or two applications. Both single and split applications of trinexapac-ethyl at 0.4 and 0.8 kg ha1 resulted in serious discoloration that could be effectively masked by Fe application. Fe tank-mixed with trinexapac-ethyl significantly improved turf color up to six weeks especially at 0.4 and 0.8 kg ha−1 rate when compared to plots treated alone with trinexapac-ethyl. Split application improved turfgrass color but to a lesser extent than Fe.