2013 ASHS Annual Conference

Increasing drought and landscape water use restrictions dictate water conservation strategies, such as switching from warm-season to cool-season turf species. Field studies were conducted in inland (Riverside) and coastal (Irvine) climates of southern California to investigate three methods (scalping, glyphosate application, no removal control) of converting an existing tall fescue (Festuca arundinacea) sward to either seed- or vegetatively-propagated warm-season turf. Cultivars established vegetatively by plugging included Tifsport hybrid bermudagrass (Cynodon dactylon x C. transvaalensis) and Sea Spray seashore paspalum (Paspalum vaginatum). Cultivars established from seed were Princess 77 common bermudagrass (Cynodon dactylon) and Sea Spray. Establishment of warm-season turfgrasses into live tall fescue (no removal control) was not effective as evidenced by only 1% groundcover in the seeded plots at the end of the study. Scalping was better but still ineffective as a conversion strategy, as none of the bermudagrasses or seashore paspalum reached 50% groundcover within one year after planting. All of the species reached a higher percentage of groundcover at the end of the study when glyphosate was applied to tall fescue before propagation compared to the other conversion strategies. 'Princess 77' and 'Sea Spray' established from seed, and 'Tifsport' from plugs provided the best overall establishment with 97%, 93% and 85% groundcover, respectively when glyphosate was used prior to establishment. In comparison, 'Sea Spray' propagated from plugs reached only 55%. Quality of seeded cultivars matched or exceeded that of cultivars established vegetatively by plugging. Location did not have an effect on final establishment suggesting that bermudagrass and seashore paspalum can adapt well in different environments. Our results suggest that eradication of cool-season turf followed by establishment of warm-season turf from seed is the best and most cost effective turf conversion strategy.