Performance of five turfgrasses under linear gradient irrigation

Determining the appropriate level of irrigation for turfgrasses is vital to the health of the turfgrass and the conservation of water, The linear grad ient irrigation system (LGIS) allows long-term assessment of turf performan ce under continuous irrigation gradients from excess to no irrigation. The objectives of this study were to: 1) evaluate the minimum irrigation requir ements and relative drought resistance of 'Rebel II' tall fescue (Festuca a rundinacea Schreb.),'Meyer' zoysiagrass (Zoysia japonica Steud,),'Tifway' b ermudagrass [Cynodon dactylon (L,) Pers,], 'Prairie' buffalograss [Buchloe dactyloides (Nutt.) Engelm], acid 'Nortam' St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze]; and 2) evaluate the long-term effects of irrig ation levels on turf persistence, weed invasion, and disease incidence for the five selected turfgrasses under field conditions. Turf was sodded under LGIS with an irrigation gradient ranging from 120% Cass A pan evaporation (Ep) to natural precipitation, along a 20-m turf area. Evaluation during th e summers of 1993-96 indicated that grasses differed in drought resistance and persistence under variable irrigation regimes. Irrigation (Ep) required to maintain acceptable turf quality for respective grasses was 'Rebel II' (67%),'Meyer' (68%),'Nortam' (44%), 'Tifway' (35%), and 'Prairie' (26%). Hi gher dollar spot (Sclerotinia homoeocarpa Bennett) infection was observed a t 115% Ep irrigation regime in 'Tifway' bermudagrass, whereas gray leaf spo t [Pyricularia grisea (Hebert) Barr] was observed only at 10% Ep irrigation regime in St. Augustinegrass plots. An outbreak of brown patch (Rhizoctoni a solani Kuehn) occurred in Sept, 1996 in St. Augustinegrass plots receivin g irrigation at >80% Ep.