In recent years, some golf courses in Hawaii have replaced or are replacing bermudagrass with seashore paspalum on greens or as their primary fairway turfgrass. Emphasis on potable water conservation and increased use of recycled water on turfgrass are major contributors to increased soil salinity (Duncan and Carrow, 1998). This increase in soil salinity has contributed to the use of seashore paspalum due to its high tolerance to saline soils and nonpotable irrigation water (Lee et al., 2004). Bermudagrass irrigated with saline nonpotable water results in unacceptable turf quality (Wiecko, 2003).
As more seashore paspalum golf courses are established, bermudagrass contamination is a common unsolved problem among Hawaii’s turfgrass managers. The only selective herbicide labeled for bermudagrass suppression in seashore paspalum is ethofumesate (Bayer CropScience, 2017a). Selective suppression of bermudagrass is attributed to higher foliar and root absorption of ethofumesate relative to seashore paspalum (McCullough et al., 2016). Bermudagrass suppression in seashore paspalum turf was achieved by sequential applications of ethofumesate plus flurprimidol. However, seashore paspalum injury was considered unacceptable for practical use (Johnson and Duncan, 2000). Ethofumesate, fluazifop, and clethodim alone or in combinations have been ineffective at bermudagrass suppression, and damage to the seashore paspalum was considered unacceptable (McCullough, 2017).
Bermudagrass control on golf courses has relied on spot treatments of glyphosate (Johnson, 1988). However, selective bermudagrass suppression has been achieved in st. augustinegrass (Stenotaphrum secundatum) with sequential applications of ethofumesate plus atrazine (McCarty, 1996). Atrazine is not labeled for use on turfgrass in Hawaii and causes unacceptable injury to seashore paspalum (Purdue University, 2018; Yu et al., 2015). Bermudagrass suppression in zoysiagrass (Zoysia sp.) was achieved with multiple applications of fenoxaprop + triclopyr or fluazifop + triclopyr (McElroy and Breeden, 2006). Fenoxaprop, fluazifop, and triclopyr cause unacceptable injury to seashore paspalum (McCullough, 2017). In this study, herbicides were evaluated for suppression of bermudagrass and seashore paspalum injury and foliar discoloration.
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