I have been fighting a weed for a few years now, all to no avail. It
is sometimes called 'wiregrass'. sometimes 'witchgrass', I think.
It grows long 'stringers' below and above ground, and when I pull one
up, sometimes the 'stringer' is a foot or two long! Terrible stuff.
I have tried a few weed killers, such as Weed-B-Gone, and weed killers
in Turf Builder. I think the danged weed feeds on that.
The local nursery tells me that you can't kill it except by using a
vegetation killer, which of course would kill grass and everything.
I hate to think of doing that.
I guess I have a few questions. First, is a vegetation killer my only
choice? If not, what else can I try? If so, when do I apply it? In
the Fall? Second, how soon after something as drastic as that can I
then plant grass seed? Seems to me that the killer would exist in the
soil for a while. Maybe years?
Unfortunately, common names for plants make them very hard to identify.
Without proper identification, it's even more difficult to find a remedy or
control. Photos of the plant would be most helpful. Posting them online
somewhere, and linking here, would be best. Your geographical location is
helpful information, also.
Looking for "witchgrass" turns up Panicum capillare. Do a search on Google
for the Latin name, and see if that's the plant.
"Wiregrass" turns up another plant altogether (Cynodon dactylon (syn.
Panicum dactylon, Capriola dactylon)), which is actually Bermuda grass.
It depends on the plant. If it's C. dactylon, timing is everything with a
non-selective herbicide. It spreads by stolons (the runners across the
surface), rhyzomes (underground), as well as seeds. You need to apply
glyphosate (ex. Roundup) at the END of the plant's growing season, when the
plant is sending food back down to the rhyzomes for storage during it's
dormant season. If you apply it during it's growing season, you'll kill the
top-growth, but the rhyzomes will send up new stolons in no time. Applying
at the end of the season, it will take the herbicide down to the rhyzome,
and effectively kill it.
If it's P. capillare, and it's in your lawn, you should apply a
pre-emergent. It's an annual. If the seeds can't sprout, the plant can't
Mow higher, seed in the fall to get the turf thicker so the "weed" can't
compete, and try not to overwater.
Apply glyphosate in the fall. Water, heck, even fertilize the invasive
pest. Make it feel welcome, get it growing and producing sugars, then ZAP
it with the herbicide. It'll never see it coming. =)
Pre-emerge in early spring.
Glyphosate won't affect the seeds. It's a contact killer. It's absorbed
through the leaves of the plant. If you're really worried, wait 7 days
-A tree never hits an automobile except in self-defence.
I'm a "do it myself" kind of guy, but I will admit that I do not have a
green thumb and don't know beans about lawncare. I do my part, mowing and
watering, but I leave chemical applications to the pros. Maybe you have a
good professional outfit in your area that could help?
i generally don't do a lot of week or bug killers but i've got
similarly tough (but unrelated weeds) and get the same advice even
from folks at the Ag station; either live with it, or else kill the
lawn completely and start over.
i'm just going to live with it, but honestly, killing the lawn and
starting over doesn't seem that out of the question; roundup or
another glyphosate product is gone very quickly, and you can seed like
the next day. i've used the stuff seriously once where i hadn't gotten
to my "garden" in time to either plant something or mulch it, and had
a gorgeous crop of 4 foot tall weeds, and it killed most everything
off very quickly; but, month later, new weeds were indeed growing
there. so there is apparently no real residual activity.
some folks appear to be sensitive to it; but in fact that appears to
be sensitivity to the "inert carrier" whatever it may be, rather than
the glyphosate itself. me, i just like to avoid routine use of
chemicals and invest my cash/time/energy more in building self-
sustaining healthy lawn, etc. but for the occasional real emergency
cases like my localized bumper weed crop i'll use some products if my
research on them doesn't produce any real red flags.
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