Herbicides and herbicide prepackaged mixtures registered for use on established bermudagrass turf may cause significant injury to recently seeded bermudagrass cultivars, delaying full establishment. Research was conducted to evaluate the use of 12 herbicide treatments applied at onset of uniform stolon development (4 to 8 wk after seeding) to recently seeded ‘Princess 77,’ ‘Riviera,’ ‘Savannah,’ and ‘Yukon’ bermudagrass cultivars. In general, Yukon was more susceptible to herbicide injury than other cultivars. Atrazine at 1.1 kg ai/ha injured all cultivars 55 to 59% 14 d after initial treatment (DAIT), which lead to reduced bermudagrass cover 21 DAIT. Triclopyr + clopyralid at 0.63 + 0.21 kg ae/ha, respectively, injured Savannah and Yukon greater than other broadleaf weed herbicides (2,4-D + mecoprop + dicamba or 2,4-D + clopyralid + dicamba). Foramsulfuron did not injure or reduce bermudagrass cover of any cultivar evaluated at any rating date. The only adverse effect of trifloxysulfuron was a reduction in Riviera and Yukon ground cover at 21 DAIT. MSMA applied sequentially and quinclorac treatments did not injure or reduce ground cover of Savannah or Princess 77. MSMA applied sequentially and/or quinclorac injured and reduced ground cover of Riviera and Yukon; however, both cultivars completely recovered from MSMA or quinclorac injury by 42 DAIT.

Studies examined the effect of herbicides on the quality and root strength of winter-installed tall fescue and hybrid bermudagrass sod. Sod was installed in February and treated approximately 30 to 45 d after installation with a variety of preemergence (PRE) and postemergence (POST) herbicides. Tall fescue quality was not affected by any herbicide treatment in 2000 or 2001. Root strength reduction occurred only in 2001 by dithiopyr applied PRE at 2.5 kg ai/ha, which is 4.5 times the maximum use rate. No other herbicides decreased tall fescue root strength in either year. Bermudagrass quality was decreased by triclopyr plus clopyralid applied POST, which resulted in 22 and 6% injury 42 d after initial treatment (DAIT) in 2000 and 2001, respectively. However, POST herbicides did not affect bermudagrass root strength in either year. PRE herbicide treatments did not reduce root development in bermudagrass in 2000. However, dithiopyr applied at 0.84 and 2.5 kg/ha reduced bermudagrass rooting by 59 and 70%, 60 DAIT, in 2001. Pendimethalin reduced root development of bermudagrass by 62% when applied at 10.2 kg/ha, three times the maximum use rate, in 2001. However, by 120 DAIT, only dithiopyr applied at 2.5 kg/ha decreased bermudagrass root development.