WHY CAN’T I KILL THAT WEED IN MY YARD? BY GEORGE EDGAR The experts on
Backyard Farmer and the instructors in the Master Gardener classes
always talk about having the “Right Plant in the Right Place. “The
Right Plant in the Right Place” means you plan ahead and if you have a
particular location you want filled, you select a plant that will be the
right height, the right width, and needs the kind of soil you have. You
also take into consideration the moisture and sun requirements. Or you
start with a particular plant you bought or want to buy and select the
location with the right amount of sun, the right amount of moisture, and
has the room for the plant to grow to its mature height and width. The same
approach applies to weeds. We say that a weed is just a plant out of
place. (Right now I haven’t found the right place for “Crabgrass”
or “Bindweed” but I suppose there is one.) For example, we have
“Bromegrass” in the “Back 40” which is 300 feet by 150 feet
between my lot line and Antelope Creek. It does not get any water other
than rain, and does not get fertilizer. It was very brown during the
drought in July and I thought sure it was dead, but when we got a 3 inch
rain it greened right up. “Buffalograss” might take a little less
mowing and be somewhat better, but would be expensive to replant the
whole area now, and would not be green in the early spring or late fall.
So for now, the Bromegrass is the right grass in the right place. However, when
the “Bromegrass” roots cross that imaginary line between the “Back
40” and my vegetable garden, it becomes a weed. I know what this weed
is and how to control it. But if you don’t know what your “Plant out
of Place” (the weed you don’t like) is in your yard or garden, or
how to control it, take a sample (more than one leaf) to a full service
garden center that has a certified nursery person or a person trained in
weed identification and control. Or take it to your local County
Cooperative Extension Educator. Identification of the weed you are
trying to kill is important and the first thing you should do. “USE THE RIGHT PRODUCT, ON THE RIGHT
PLANT, AT THE RIGHT TIME!!!” Also it is
helpful to know the life cycle of the weed. By life cycle I mean is it
an annual or a perennial? Does it grow from seed or does it spread from
runners, or both? If it
produces seeds, when do they mature, and then what time of year do they
germinate? Also, can the weed seeds be controlled by a pre-emergence
herbicide? Timing in the application of a herbicide is very important
and knowing the life cycle of the weed helps us to know what time of
year to apply the herbicide, what kind of herbicide to apply, and how
often to apply.
The most common weeds found in our lawns, flower gardens, and
vegetable gardens can be grouped as follows: ·
Annual grasses such as
Crabgrass (Digitaria sanguinalis),
Annual Bluegrass (Poa annua),
Foxtail (Setaroa glauca) and
Goosegrass (Eleusine indica). ·
Annual Broadleaf weeds such
as Prostrate Spurge (Euphorbia
supina), Spotted Spurge (Euphorbia
maculata), Black Medic (Medicago
lupulina), Pennycress (Thlaspi
arvense), Purslane (Portulaca
oleracea), Henbit (Lamium
amplexicaule) and Common Chickweed (Stellaria
media). ·
Perennial broadleaf weeds
such as Dandelion (Taraxacum
officinal), White Clover (Trifolium
repens), and Ground Ivy (Glechoma
microcarpa). ·
Perennial grasses such as
Bromegrass (Bromus inermis),
Rough Bluegrass (Poa trivialis),
Tall Fescue (Festuca arundinacea),
Nimblewill (Muhlenbergia schreberi) and Quackgrass (Agropyren
repens). ·
Perennial sedge such as
Yellow Nutsedge. Most people call it “Nutgrass” but it is really a
sedge so does not respond to weed killers like a grass. Correct
identification of the weed is important as use of the wrong weed killer
may kill everything or may not kill the weed you want to kill. I have
heard some people say that when they applied a specific product it
seemed to make the weed grow faster. That may be true, as some weed
killers such as 2-4-D are really growth regulators. They work by making
plants grow so fast they die, just as too much nitrogen fertilizer on
your lawn at the wrong time will burn it and may kill it. So, if you
don’t have the right product, on the right plant, you may only
encourage the growth of the weed and not kill it.
Be aware that
after identification, and knowing about the life cycle, one herbicide
(weed killer or preventer) will not kill or prevent everything we call a
weed. And some herbicides are ok for the lawn but should not be used in
the vegetable garden. Also some herbicides kill the weeds
(post-emergence) and some herbicides prevent the seeds from germinating
(pre-emergence). “USE THE RIGHT PRODUCT, ON THE RIGHT
PLANT, AT THE RIGHT TIME!!!” Some of the
most common herbicides include: ·
Trimec (Earl May Weed
Killer, Ortho Weed-Be-Gone, and Ortho Chickweed, Spurge, & Oxalis
Killer) is a broadleaf weed killer and will kill Dandelions, Common
Chickweed, Black Medic, Purslane, Ground Ivy, and Henbit but will not
kill Bluegrass, Turf Type Tall Fescue, Bromegrass, Buffalograss, or
Crabgrass. Triclopyr and Clopyralid are also broadleaf weed killers that
are effective on most of the above weeds. ·
MSMA (Monosodium
methanearsonate) will kill Crabgrass and Yellow Nutsedge (Nutgrass) but
will not kill Bluegrass and Turf Type Tall Fescue. ·
Manage will kill Yellow
Nutsedge (Nutgrass) but not Crabgrass, Bluegrass, or Fescue.
·
Fluazifop (Acme
Grass-No-More, Ortho Grass-B-Gone) will kill many annual grasses and
some perennial grasses in your flower bed such as Bluegrass, Tall
Fescue, and Quackgrass, but will not kill many flowers such as Iris,
Geranium, Daylily, and Peony. Will also not kill many shrubs, trees,
cactus, and green fountain grass (ornamental grass) if applied as
directed in the instructions. ·
Glyphosate (Kleen-up,
Round-up) will kill many green plants including trees, shrubs, flowers,
and grasses but won’t kill Purslane, Prickly Pear Cactus, and many
succulents. “USE THE RIGHT PRODUCT, ON THE RIGHT
PLANT, AT THE RIGHT TIME!!!” For
more information on lawn weed control go to http://ianrhome.unl.edu/search.
In the top box scroll down to “Extension Publications” and in the
bottom box type in G1045 or “Weed Prevention and Management”. Listed
will be publications you can read, and/or print for reading later and
for reference. Or go to http://lancaster.unl.edu
for garden and lawn information, good tips, and access to other
websites. In writing this
article I also used “Integrated Turfgrass Management for the Northern
Great Plains” by Frederick P. Baxendale, Ph.D. & Roch E. Gaussoin,
Ph. D. (members of the University of Nebraska Turfgrass Science Team).
Published by the Cooperative Extension Service, Institute of Agriculture
and Natural Resources, University of Nebraska: 1997. Copyright Sept. 10,
2005 |