Much research has evaluated herbicide safety on established bermudagrass turf (Cynodon dactylon), but information is lacking on seedling response to herbicides. Three field experiments were conducted in Blacksburg, Virginia (USA), to assess turfgrass and smooth crabgrass (Digitaria ischaemum) response to selected sulfonylurea herbicides during seedling bermudagrass establishment. Herbicides injured bermudagrass at 9 weeks after treatment in the following order from most to least injurious: flazasulfuron=trifloxysulfuron > rimsulfuron > metsulfuron=sulfosulfuron > foramsulfuron. Herbicides applied at 3 weeks after sowing (WAS) were generally more injurious than when applied one WAS. Flazasulfuron and trifloxysulfuron-sodium controlled smooth crabgrass greater than 90 at 6 WAS, and metsulfuron and rimsulfuron suppressed smooth crabgrass 76 and 84, respectively. Foramsulfuron, metsulfuron, and sulfosulfuron appear safe to apply one and 3 WAS, causing very little chlorosis and no reduction in turf cover. Rimsulfuron is injurious when applied at those timings; however, long-term cover is not reduced. Flazasulfuron and trifloxysulfuron-sodium are not safe to use at one and 3 WAS unless weed pressure is extreme, and a delay in bermudagrass cover is acceptable.
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