Foxtail is a summer annual weed that can easily become a perennial issue in naturalized roughs. Foxtails are prolific seed producers, and the seed can be viable for several years after dispersal, which complicates control into the future. Foxtail begins to germinate in the spring when soil temperatures reach 68 degrees F. This is later than the typical preemergence timing of around 55 degrees F used for crabgrass and other summer annual grassy weeds, making this challenging weed even tougher to manage.
Heavy populations of foxtail are often seen in low-input areas, where the existing turf cover is thin. In rough or lawn settings, foxtail is generally controlled by having a strong, dense stand of turf. However, in a stand of naturalized rough where high density is not desired, there are plenty of opportunities for foxtail to establish and spread. Preemergence herbicides like dithiopyr, pendimethalin and prodiamine are commonly employed to control summer annual weeds like crabgrass; but with foxtail’s later germination window, early preemergence applications may no longer be effective. Split applications of preemergence herbicides help control foxtail later into the summer.
If your naturalized roughs are primarily fine fescue, Group 1 (ACCase inhibitor) herbicides like sethoxydim, fluazifop or pinoxaden can provide beneficial postemergence control of foxtail, Kentucky bluegrass, tall fescue, creeping bentgrass and other grassy weeds. Avoid overspray of Group 1 herbicides into the mown rough as it can injure the turf. If you are intentionally maintaining naturalized roughs with high populations of tall fescue, Kentucky bluegrass or creeping bentgrass, Group 1 herbicides could damage populations and should not be considered. These herbicides can’t be combined with MCPA broadleaf herbicides without antagonistic effects.
Foxtail inflorescences contain lots of seeds (around 50 seeds per seedhead) that can be viable for many years after dispersal. Choosing not to control foxtail will result in a higher population of seeds in the soil in the future, so it’s a good idea to stay on top of this weed. If you have any questions about weed control in naturalized areas, please reach out to your regional USGA agronomist.
Central Region Agronomists:
Zach Nicoludis, regional director, Central Region – znicoludis@usga.org
Tom Gould, agronomist – tgould@usga.org