Multi-Year Comparison of Pre-Emergent Herbicides Commonly Used in Turfgrass.

Many pre-emergent herbicides are used in turfgrass to control summer and winter annual weeds. However, limited information is available that directly compares many of these herbicides. Research was conducted to compare indaziflam at 0.07 kg ha^-1 (Specticle; Bayer Environmental Science, Research Triangle Park, NC), oxadiazon at 3.36 kg ha^-1 (Ronstar 2G; Bayer Environmental Science), prodiamine at 1.12 kg ha^-1 (Barricade 65WG; Syngenta Crop Protection, Greensboro, NC), pendimethalin 2.24 kg ha^-1 (Pendulum Aquacap; BASF Corporation, Research Triangle Park, NC), dimethenamid at 1.68 kg ha^-1 (Tower; BASF), dithiopyr at 1.68 kg ha^-1 (Dimension 2EW; Dow AgroSciences, Indianapolis, IN), atrazine at 1.12 kg ha^-1 (Aatrex 4L, Syngenta), simazine at 1.12 kg ha^-1 (Princep 4L, Syngenta), pendimethalin at 2.24 kg ha^-1 + dimethenamid at 1.68 kg ha^-1 , and prodiamine + sulfentrazone (Echelon 4 SC at 1.12 kg ai ha^-1; FMC Corporation, Philadelphia, PA) for crabgrass (Digitaria spp.) and annual bluegrass (Poa annua) control from 2010 to 2012. All treatments were applied according to label recommendations. Visual percent control ratings were collected monthly throughout the respective seasons. Crabgrass control trials were initiated in late-February to early-March and annual bluegrass control trials were initiated in early-September each year. These application timings are typical for central Alabama. Indaziflam, oxadiazon, and prodiamine were the best treatments for crabgrass control, resulting in 90 to 95% control throughout the season. Dithiopyr, pendimethalin, pendimethalin + dimethanamid, and prodiamine + sulfentrazone resulted in 60 to 80 % crabgrass control, in July, August, and September. Other treatments resulted in less than 50% crabgrass control. Annual bluegrass control was best with indaziflam, prodiamine, and prodiamine + sulfentrazone, which resulted in 80 to 100% control throughout the season. Oxadiazon resulted in 65 to 90% annual bluegrass control throughout the season, while other treatments resulted in less than 50% control. Overall, the best performing pre-emergent herbicides for both crabgrass and annual bluegrass control in these trials were indaziflam and prodiamine.