Bermudagrass (Cynodon spp.) turf in subtropical Florida normally requires higher levels of N than other grasses and frequently requires pesticide applications. Three sequential 2-year cycles of clonal selection were performed in replicated field plots to recognize bermudagrass germplasm adapted to suboptimal fertilization and natural pest infestation. Low fertility, 19 to 25 g N·m−2, was applied yearly, including the establishment phase. No nematicides, fungicides, or insecticides were applied. Severely damaging mole cricket (Scapteriscus sp.) populations were left uncontrolled. Among 95 clones, 4 experimentals (FB-109, PI-291586, T-72-54, and FL-2400) survived repeated cycles with relatively high turfgrass coverage and quality. Among cultivars, only ‘Tifgreen-II’ and ‘Ormond’ performed well. African introductions and artificially-induced mutants of hybrid cultivars were the best sources of adapted germplasm. Although the mechanism of this adaptation is unknown, field tests were an effective prescreening method for clonal selection.
Visual evaluations of a 5-year-old replicated planting of 63 zoysiagrass (Zoysia spp.) genotypes in southern Florida showed highly significant (P < 1%) differences in overall vigor and survival, flight selections and 2 commercial cultivars (‘Emerald’ and ‘Meyer’) were sodded at 2 distant sites. Selected genotypes (FZ-28, FZ-80, FZ-26, and FL-1753) were significantly better adapted, had significantly less weed encroachment and greater vigor and ground coverage, than Emerald or Meyer. The latter commercial cultivars were unacceptable in most evaluations. Furthermore, FZ-28 and FZ-80 had low sting nematode (Belonolaimus longicaudatus Rau) counts and FZ-28 had few eggs of Banks grass mite (Oligonychus pratensis [Banks]). Sod webworm (Crambus spp.) infestation appeared to be another variable closely associated with adaptive differences among genotypes and explained serious establishment problems at some sites. Zoysiagrass was successfully established as a turf only on one site involving fumigated soil and generally proved poorly suited for this subtropical region.