Response of Hybrid Bermudagrass (Cynodon dactylon× C.transvaalensis) to Three HPPD-Inhibitors

Abstract

Mesotrione, topramezone, and tembotrione inhibit 4-hydroxyphenylpyruvate dioxygenase (HPPD), an enzyme integral to carotenoid biosynthesis. Research was conducted to evaluate the response of hybrid bermudagrass following mesotrione (280, 350, and 420 g ai ha−1), topramezone (18, 25, and 38 g ai ha−1), and tembotrione (92, 184, and 276 g ai ha−1) applications. Measurements of visual bleaching (VB) and chlorophyll fluorescence yield (Fv/Fm) were evaluated 3, 5, 7, 14, 21, 28, and 35 d after application (DAA). Leaf tissues were sampled on the same dates and assayed for chlorophyll and carotenoid pigments using high-performance liquid chromatography (HPLC). Responses of plants treated with topramezone and tembotrione were similar; these herbicides caused more VB and greater reductions in Fv/Fm, total chlorophyll, lutein, and xanthophyll cycle pigment concentrations than mesotrione 5 to 21 DAA. Increasing mesotrione application rate did not increase VB or lead to greater reductions in total chlorophyll, lutein, or xanthophyll pigment concentrations. Alternatively, increasing topramezone and tembotrione application rates above 18 and 92 g ha−1, respectively, extended VB and pigment reductions. Of the three HPPD-inhibitors tested, topramezone was the most active, because the low (18 g ha−1) rate of topramezone reduced lutein and total xanthophyll pigment concentrations more than the low rate of tembotrione (92 g ha−1) during periods of maximum activity (14 to 21 DAA). No necrosis was observed with any of the treatments, suggesting tank mixtures of topramezone with other herbicides might be required to provide long-term control of hybrid bermudagrass.

Immediate Irrigation Improves Turfgrass Safety to Postemergence Herbicides

“…Cox et al (2017) noted similar turfgrass injury 2 WAT with topramezone. Elmore et al (2011b) reported turfgrass injury from topramezone was greatest 2 WAT (%47%), although in our study the turfgrass injury was greater (up to 81%). Simazine and mesotrione treatments alone maintained acceptable turfgrass injury (%13%); however, when applied in combination, considerable (up to 27%) turfgrass injury occurred.…”

“…Simazine and mesotrione treatments alone maintained acceptable turfgrass injury (%13%); however, when applied in combination, considerable (up to 27%) turfgrass injury occurred. Elmore et al (2011b) noted acceptable mesotrione turfgrass injury throughout a 5-week study. Simazine alone provided acceptable turfgrass injury (#30%), consistent with previous research (Sharpe et al, 1989).…”

Controlling Dinitroaniline-Resistant Goosegrass (Eleusine indica) in Turfgrass

“…Topramezone injury may be unacceptable to turf managers; however, this response was transient, as injury was ≤ 6% 28 DAT and 0% by 50 DAT. These responses support previous findings by Elmore et al (2011), Brosnan et al (2011), and Cox et al (2017) following topramezone applications to bermudagrass. By 21 DAT in a glasshouse, topramezone applications at 18 to 38 g ha -1 injured 'Tifway' hybrid bermudagrass 35% to 40% and 'Riviera' common bermudagrass 46% to 58% (Brosnan et al 2011;Elmore et al 2011).…”

African star grass response to postemergence herbicides

“…Tembotrione was applied to hybrid Bermuda grass (C. dactylon x C. transvaalensis) plants (Elmore et al, 2011). The herbicide caused high values of bleaching measurements and great reductions in total chlorophyll, lutein, and xanthophyll cycle pigment concentrations.…”