Aerial and ground‐based assessments of preemergence herbicide effects on St. Augustinegrass grow‐in

AbstractPreemergence herbicides reduce weed competition during turfgrass establishment, yet little is known regarding preemergence herbicide safety on plugged St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze]. Field research was conducted in 2019 to evaluate the effects of prodiamine, pendimethalin, liquid‐ and granular‐applied oxadiazon, S‐metolachlor, atrazine, atrazine + S‐metolachlor, dithiopyr, and indaziflam on St. Augustinegrass grow‐in. St. Augustinegrass was established vegetatively. Herbicides were applied one day after planting. Visual cover and multispectral reflectance (handheld and aerial) were collected weekly. Chlorophyll Index‐Red Edge (CI‐RE), Ratio Vegetation Index (RVI), and Normalized Difference Vegetation Index (NDVI) were calculated. Indaziflam, which is not labeled for St. Augustinegrass grow‐in or sod production, was included as a treated check and increased days to reach 50% cover and maximum index values from handheld and aerial methods. Prodiamine increased days to reach 50% cover for all response variables except aerial‐derived CI‐RE and RVI. Atrazine as well as granular‐ and liquid‐applied oxadiazon did not increase time to reach 50% visual cover and maximum vegetation index responses relative to the nontreated.