Goosegrass is a warm-season annual very similar to crabgrass, but germinates later than crabgrass and is tougher to control with both pre- and postemergence herbicides. It is most common in compacted, poorly drained soil, and/or thinned, heavily used turf, so cultural practices to help alleviate these conditions are essential to minimize goosegrass. If populations are low, cutting goosegrass out with a knife is the most effective method. Best control is with sequential applications of preemergence herbicides, which are usually required to fully control late germinating goosegrass. However, this is problematic in bentgrass greens with very few products labeled for greens.
Postemergence control of goosegrass is more difficult and there are no reliable options. Dithiopyr (Dimension, Dithiopyr) does not control goosegrass, except possibly for very small plants. In spite of some recommendations, quinclorac (Drive, QuinStar, Quinclorac, and other combinations products) will not control goosegrass. Fenoxaprop (Acclaim) may be the best current postemergence control for goosegrass, but phytotoxicty can be an issue on Kentucky bluegrass and especially creeping bentgrass. Be sure to follow label instructions for using Acclaim on creeping bentgrass, as frequent applications at very low rates are needed. Tenacity will control goosegrass on Kentucky bluegrass golf courses and athletic fields, but this is not for use on creeping bentgrass. Multiple applications of sulfentrazone (FMC’s Dismiss) has also been shown to control goosegrass. Speedzone (carfentrazone+2,4-D+MCPA+dicamba) was easily the best performer on goosegrass last year in our studies as well in as wide-ranging anecdotal observations. Though Dismiss did not perform well in last year’s study on goosegrass, we suspect the rate was slightly low and we will be increasing the rate to 6 oz/A this year. Speedzone is currently not labeled for goosegrass, but it is labeled for use on most areas in golf and sports turf. Last year’s data indicate adequate turf safety on fairway height creeping bentgrass and perennial ryegrass (Kentucky bluegrass or annual bluegrass were not tested). In addition to last year’s study, we also have studies evaluating seedling safety of Speedzone (for reseeding tees) and other goosegrass control studies. All of these will be discussed at Field Day on July 24th (http://www.nebraskaturfgrass.com/wp-content/NE-Turf-Association-attendees-c.pdf).
Zac Reicher, Professor of Turfgrass Science, zreicher2@unl.edu