Effects of Preemergence Herbicides on Sprigged Establishment of Hybrid Bermudagrass.

Preemergence herbicides often negatively affect establishment of sprigged hybrid bermudagrass (Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy). However, limited research has quantified the effects of preemergence herbicides commonly used in warm-season sod production of the southeastern United States. Research was conducted at Mississippi State University during summer 2016 to evaluate the effects of atrazine (1.12 kg ha^-1), atrazine (1.12 kg ha^-1) + metolachlor (0.86 kg ha^-1), dithiopyr (0.56 kg ha^-1), flumioxazin (0.286 kg ha^-1), indaziflam (0.033 kg ha^-1), liquid and granular applied oxadiazon (2.24 kg ha^-1), metolachlor (2.78 kg ha^-1), pendimethalin (1.66 kg ha^-1), prodiamine (0.594 kg ha^-1), and simazine (2.24 kg ha^-1) on sprigged ‘Latitude 36' hybrid bermudagrass establishment. Plots (4.65m²) were sprigged at a rate of 44 m³ ha^-1 (468 US bushels ac^-1) on May 10, 2016. Visual assessment of % cover, as well as ratio vegetation index (RVI), normalized difference vegetation index (NDVI), and relative chlorophyll concentration (Cl-RE) were recorded every two weeks throughout the experiment. Regression analysis was used to estimate days (d) to 50% cover. Confidence intervals at α = 0.05 level of significance were used to detect differences compared to the nontreated. Data measured 8 and 12 weeks after treatment (WAT) were subject to means separation. Indaziflam (839 d), metolachlor (80 d), dithiopyr (96 d), and flumioxazin (79 d) increased estimated time to 50% cover when compared to the nontreated (55 d). At 8 WAT and 12 WAT, dithiopyr and indaziflam reduced NDVI values compared to the nontreated. Metolachlor, flumioxazin, dithiopyr, and indaziflam reduced visual ratings of cover when evaluated 8 WAT; however, only indaziflam reduced visual ratings of cover 12 WAT. No differences were detected in RVI values 8 WAT; however, dithiopyr and indaziflam reduced RVI values 12 WAT. Indaziflam reduced C1-RE when evaluated 8 and 12 WAT. A second replication of this study will be completed during summer 2017.