Ergot Resistant Tetraploid Bahiagrass and Fungicide Effects on Seed Yield and Quality

Rios, E., Blount, A., Harmon, P., Mackowiak, C., Kenworthy, K., and Quesenberry, K. 2015. Ergot resistant tetraploid bahiagrass and fungicide effects on seed yield and quality. Plant Health Progress doi:10.1094/PHP-RS-14-0051. Seed production is a critical component in agricultural systems based on bahiagrass and ergot has been reported to significantly reduce seed quality in tetraploid cultivars. Seed yield and quality are important traits to evaluate in the advanced breeding lines developed at the University of Florida. Resistance to ergot was assessed in seven tetraploid bahiagrass breeding lines and the cultivar Argentine. Tebuconazole and pyraclostrobin also were evaluated for managing ergot and increasing seed quality. Argentine and two tetraploid hybrids (Hyb1 and Hyb2) showed the highest levels of ergot severity and incidence. Three wild-type bahiagrass lines (WT-2, WT-4 and WT-5) performed significantly better than Argentine and could be considered resistant to ergot. Anthesis was the critical stage in relation to ergot infection, and a single application of tebuconazole at anthesis reduced ergot severity; however, neither fungicide was able to reduce ergot incidence. Tebuconazole and pyraclostrobin improved seed set, and reproductive efficiency was 2.4% higher after the application of tebuconazole. The slight increase in reproductive efficiency following fungicide application may not be economically justifiable for seed production in bahiagrass. Three advanced tetraploid breeding lines (Hyb1, WT-3, and WT-5) exhibited adequate seed production to be considered for cultivar release.