Research was conducted in winter of 2000 and spring of 2001 to determine the extent of simazine-resistant annual bluegrass in Mississippi. Samples of annual bluegrass seed or mature plants were collected from 71 locations across the state and grown in the greenhouse. Four weeks after treatment with 22.4 kg ai/ha simazine (10× rate), samples from 31 of 71 locations (30 golf courses and one nongolf course) evaluated in the greenhouse had simazine-resistant annual bluegrass plants. Thus, 43% of the golf courses tested in the greenhouse had triazine-resistant annual bluegrass present. When natural field populations were treated with an equivalent simazine rate, simazine-resistant annual bluegrass plants were observed in 90% of the sites found to be resistant in the greenhouse screen.

Hand-held hyperspectral reflectance data were collected in the summers of 2002, 2003, and 2004 to differentiate unique spectral characteristics of common turfgrass and weed species. Turfgrass species evaluated were: bermudagrass, ‘Tifway 419’; zoysiagrass, ‘Meyer’; St. Augustinegrass, ‘Raleigh’; common centipedegrass; and creeping bentgrass, ‘Crenshaw’. Weed species evaluated were: dallisgrass, southern crabgrass, eclipta, and Virginia buttonweed. Reflectance data were collected from greenhouse and field locations. An overall classification accuracy of 85% was achieved for all species in the field. A total of 21 spectral bands between 378 and 1,000 nm that were consistent over the three data collection periods were used for analysis. Only centipedegrass, zoysiagrass, and dallisgrass were correctly classified less than 80% of the time. An overall classification accuracy of 69% was achieved for the greenhouse species. Spectral bands used in this analysis ranged from 353 to 799 nm. Creeping bentgrass and Virginia buttonweed were classified correctly at 96 and 92%, respectively.

Research trials conducted at two locations in the spring of 2004 evaluated the effect of soil temperature as an indicator for application timings of certain sulfonylurea herbicides for perennial ryegrass control while maintaining acceptable turfgrass quality during bermudagrass spring transition. Herbicide application timings began when soil temperatures reached 17 C (April 14, 2004). Greater perennial ryegrass control 4 wk after initial treatment (WAIT) was achieved when sulfonylurea herbicides were applied at 26 C soil temperature compared to 17 or 21 C. Bermudagrass density 6 WAIT increased with treatments applied at 26 C soil temperature compared to cooler soil temperatures. There was a decrease in overall turfgrass quality 2 WAIT when treatments were applied at 17 C. However, by 4 WAIT all application timings provided overall turfgrass quality comparable to the untreated control. Acceptable turfgrass quality and maximum perennial ryegrass control was achieved by delaying transition-aid herbicide applications until soil temperatures reached 26 C and growing conditions were more conducive to bermudagrass growth.

Southern crabgrass is a major weed in turfgrass and it primarily is controlled through preemergence herbicide application. Separate studies were conducted to evaluate the efficacy of trifloxysulfuron and flazasulfuron alone and in tank mixtures for southern crabgrass control in bermudagrass as MSMA alternatives. In 2001, two applications of trifloxysulfuron at 0.03 kg ai/ha 6 wk apart controlled southern crabgrass equal to MSMA applied twice at 2.2 kg ai/ha 7 d apart (91% compared to 90%, respectively) 90 d after initial treatment (DAIT), but provided greater control than MSMA in 2002 (80 versus 74%, respectively) 90 DAIT. Two applications of trifloxysulfuron at 0.02 kg/ha tank mixed with MSMA at 1.1 kg/ha controlled southern crabgrass 90%, greater than either two applications of trifloxysulfuron or MSMA applied alone (80% and 74%, respectively). In the second study, flazasulfuron applied at 0.05 kg ai/ha tank mixed with prodiamine at 1.1 kg ai/ha, pendimethalin at 1.6 kg ai/ha, or quinclorac at 0.84 kg ai/ha controlled southern crabgrass greater than a single application of MSMA at 2.2 kg/ha 60 DAT. In both 2005 and 2006 flazasulfuron applied alone provided similar or greater southern crabgrass control compared to a single application of MSMA at 2.2 kg/ha 60 DAT. At the conclusion of these studies, trifloxysulfuron and flazasulfuron alone or in tank mixtures controlled southern crabgrass similar to or better than MSMA; therefore these would be effective alternatives to MSMA in bermudagrass.

Path rush can become problematic on golf course fairways, especially on roughs where continuous golf cart or maintenance equipment traffic occurs. Research trials conducted in 2003 and 2004 compared the efficacy of 2,4-D and mixtures containing 2,4-D in single or sequential applications to herbicides without 2,4-D for path rush control in bermudagrass roughs. Sequential applications of 1.1 kg ae/ha 2,4-D or 0.8 + 0.2 + 0.1 kg ae/ha 2,4-D + MCPP + dicamba provided 95% path rush control with no injury to bermudagrass, 15 wk after initial treatment (WAIT). Single applications of 1.1 + 0.3 + 0.1 kg/ha 2,4-D + MCPP + dicamba or 1.1 kg/ha 2,4-D provided at least 81% path rush control, 15 WAIT. Treatments without 2,4-D did not provide acceptable levels of control (34% or less, 15 WAIT). 2,4-D applied alone or in preformulated mixtures provided excellent path rush control compared to treatments without 2,4-D. Sequential applications of these treatments provided greater path rush control than single applications. However, only the sequential application of 0.8 + 0.2 + 0.1 kg/ha 2,4-D + MCPP + dicamba provided greater path rush control than the single application. Results from these studies suggest that 2,4-D is a key herbicide for path rush control.