Spring is a great time to use postemergence herbicides on
creeping bentgrass and quackgrass and to control tall fescue
problems in desirable turfgrass.
Creeping bentgrass is a desirable turf, but it becomes a
problem when it invades other cool-season turfgrasses. It
forms dense patches and is characterized by soft,
fine-textured (narrow), blue-green leaf blades and
above-ground creeping stems called stolons.
The appearance and growth habits of quackgrass and tall
fescue are much different than those of creeping bentgrass.
Quackgrass has coarse-textured (wide) blue-green leaves with
long, clawlike auricles (appendages where the leaf blade
meets the stem). Quackgrass typically does not appear as
distinct clumps in turf. It spreads by strong rhizomes, or
horizontal underground stems. If you pull up quackgrass, the
long white rhizomes will be visible. Quackgrass seeds and
rhizomes will often find their way into lawn areas in
The leaves of tall fescue are dark, emerald green, and
coarse-textured. Tall fescue does not normally spread by
above- or below-ground horizontal stems. It is apparent in
lawns as clumps that grow more rapidly than the other lawn
grasses it has invaded. It normally stands out several days
after mowing because it grows taller and faster than the
desirable species, resulting in a patchy appearance in most
Controlling these perennial grassy weeds is often difficult.
One option is to pull or dig them out. Get as much of the
roots as possible, including the stolons on creeping
bentgrass and the rhizomes on quackgrass. Preemergence
herbicides that prevent annual grasses such as crabgrass
will not control these weeds.
No selective herbicides are available for creeping bentgrass
and quackgrass, but the nonselective herbicide glyphosate
(Roundup, Kleeraway) can be used to control these weeds and
tall fescue as well. For the most effective control, apply
herbicides when the weeds are green and actively growing.
Glyphosate can damage or kill other actively growing plants
it comes into contact with, so caution is advised. In the
case of creeping bentgrass and quackgrass, be sure to spray
an area large enough to include all of the creeping stems
growing in the area; untreated stolons or rhizomes may
continue to grow and develop into more unsightly weeds.
Chlorsulfuron (TFC) is a selective postemergence herbicide
that can be applied to control actively growing tall fescue
that has invaded Kentucky bluegrass. Chlorsulfuron often
works slowly, causing the tall fescue to decline gradually
rather than die quickly. It will kill or damage perennial
ryegrass and may also cause yellowing or phytotoxicity to
After the weeds have been removed or killed, the area needs
to be replanted. Sod can be installed in the dead areas, or
they can be reseeded. While the best time to reseed is late
August and early September, the cool-season perennial grassy
weeds may not be actively growing at that time.