1. Effects of Postemergence Herbicides on Centipedegrass Seed Production J. A. Ferrell, T. R. Murphy, W. K. Vencill University of Georgia

2. Centipedegrass popularity Propagated via seed or sod Low maintenance –Slow growth –Low nitrogen requirement Herbicide tolerance –Sethoxydim and clethodim –Halosulfuron

4. Changing Needs Traditional Emphasis Color Seedhead Suppression Weed Control Production Emphasis Seed Yield Seed Quality Weed Control

5. Digitaria sanguinalis

6. Cyperus esculentus

7. Objectives Determine the impact of herbicide and treatment timing on: Seedhead suppression Seed yield Seed quality

8. Herbicide Treatments Herbicides Clethodim Sethoxydim Halosulfuron Spray Timing -4 WPS* -2 WPS 0 WPS (Late July) 2 WPS 4 WPS * Weeks post seedhead emergence

9. Materials and Methods Macon County, Georgia seed farm –Greenville clay loam Established centipedegrass (cv. ‘TifBlair’) Irrigated, weed-free site Plot size – 6’ X 20’ 3 replications

10. Materials and Methods Clethodim – 0.25 lb ai A -1 + 0.25% v/v NIS Sethoxydim – 0.28 lb ai A -1 Halosulfuron – 0.062 lb ai A -1 + 0.5% v/v NIS 25 GPA, flat fan nozzles, CO 2 backpack Seedhead suppression –0 to 100 scale 3 x 5 factorial Analysis: herbicide within treatment timing

11. Seedhead Suppression

12. TimingClethodimSethoxydimHalosulfuron 4 WBSNS 2 WBSNS 0 WBS NS 2 WPS NS 4 WPSNS NS – non significant

13. Seedhead Suppression (0 WPS) Herbicide2 WAT4 WAT 2001200220012002 % Clethodim5012310 Sethoxydim21333

14. Seedhead Suppression (2 WPS) Herbicide2 WAT4 WAT 2001200220012002 % Clethodim3316235 Sethoxydim180130

15. Seed Yield October 10, 2001 Harvested 2 randomly selected m 2 quadrants Seeds removed from heads with mechanical thrasher

16. Seed Yield

17. Seed Germination Conducted by Georgia State Seed Test Lab Conditions: –Covered petri dish with moist paper –Temperature – 20 to 35 o C –Counts – 7 and 21 days

18. Seed Germination

19. Conclusions Halosulfuron does not affect centipedegrass seed yield or germination Apply clethodim or sethoxydim as early as possible (minimum 4 WBS) Once seedheads emerge, use of clethodim or sethoxydim is not advisable

20. Future Centipedegrass Research Investigate effect of clethodim and sethoxydim in salvage situations (6, 8, 10 WPS) Effect of other commonly used herbicides on seed yield and quality Develop weed management systems in seedling centipedegrass

21. Acknowledgements Valent USA The Turfgrass Group Bill Nutt - technical assistance

22. www.bmen.tulane.edu/~mroberts Any Questions?