Preemergence herbicide effects on St. Augustinegrass establishment

St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] is one of the most common turfgrass lawn species of warm-season climates. Like many turfgrasses, it is produced as sod. Weed control during sod production is problematic, due in part to intolerance of St. Augustinegrass to a range of useful turfgrass herbicides, and because the open canopy and growth-conducive conditions of sod production favor certain difficult-to-control weeds. Although those weeds are best preventatively controlled using preemergence herbicides, many preemergence herbicides also adversely affect vegetative propagation of turfgrasses. Field research was conducted at the Mississippi State University, near Starkville, Mississippi, USA, to evaluate the effects of dithiopyr, pendimethalin, prodiamine, liquid- and granular-applied oxadiazon, atrazine, S-metolachlor, atrazine + S-metolachlor, and indaziflam on St. Augustinegrass establishment from plugs. Plots (2.25 m(2)) were planted with 10 plugs (225 cm(2) apiece), and preemergence herbicides were applied at standard use rates 1 day after planting. Visual estimates of percentage cover were collected weekly, and aerial imagery was collected weekly to biweekly. Visual cover and vegetation index data were regressed to estimate days to reach 50% maximum nontreated response. Liquid-applied oxadiazon and atrazine were the only treatments that did not increase days to reach 50% cover in both replication years. Dithiopyr, prodiamine, S-metolachlor, and indaziflam increased days to reach 50% cover in both replication years. The normalized difference vegetation index, ratio vegetation index, and chlorophyll index-red edge derived from an aerial sensor, detected similar, but fewer, treatment differences compared to estimated visual cover.