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WEED OF THE WEEK - WHITE CLOVER
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B: Today's weed of the week is a crop for many farmers, but in corn,
soybeans, and lawns, it can be a devastating weed. It's white clover.
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D: We'll talk about why white clover can be so harmful, and we'll
show you how to identify it.
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B: Plus, stay tuned, because we'll show you how you can eliminate
white clover, for good.
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D: Let's start first with identification. White clover is a legume
in the bean family. It is a perennial weed that reproduces both
by seed and by stolons. Stolons are just like
rhizomes, except they run above the surface of the soil rather than
below it.
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 B:
The leaves of a white clover plant look very similar to alfalfa,
but they do have one distinguishing characteristic, a white line
that runs across each leaf in a semi-circle. The tips of each leaf
are rounded to notched, and the leaf margins are slightly toothed.
The leaves are smooth, without hair, and they run alternately up
the stem of the plant.
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D: The flowers of white clover plants are white, but occasionally
have a little pink in them. The pod-shaped seed clusters will be
right below the flowers, and each pod typically has 2 to 4 seeds.
Each seed is heart-shaped, yellow, and smooth.
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B: The stems of this weed are also usually smooth, but can have
small hairs. The stems are considered creeping, as the stay close
to the ground as they grow. Therefore, white clover is rarely taller
than 6 inches in height. In terms of the root system, white clover
has both a taproot and fibrous roots.
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D: Once you've identified white clover, you'll need to determine
if it is harmful or beneficial in your situation. Certainly, if
it is found in a field of another crop or in a lawn, it is a weed
and it should be controlled. It is a perennial plant that is tough
to kill once it is established. Plus, if it is in a pasture, cattle
can become bloated by eating much white clover. So it can definitely
be a troublesome plant.
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B: However, it can also be a beneficial plant. White clover is just
like the other legumes, in that it fixes nitrogen. The roots of
the plant release sugars for bacteria to feed on. The bacteria then
convert atmospheric nitrogen into a form the plant can use, thus
creating a symbiotic relationship. In areas where it is simply important
to establish some kind of vegetation, like in road ditches, white
clover can be a nice plant to have. It thrives in tougher conditions,
and it produces its own nitrogen, so fertilizing is usually not
necessary.
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D: White clover also provides an excellent food source and habitat
for many animals. Deer, turkeys, and other small mammals commonly
feed on the leaves of the plant. The seeds are eaten by grouse and
other birds. So again, white clover definitely has its benefits…
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B: but on Ag PhD, it's a weed. So let's get into our favorite part
of the show, how it kill it. We'll start with lawns. White clover
seems to thrive in many lawns, since it creeps along the ground,
below the reach of lawnmowers. Plus, while 2,4-D is the most commonly
used lawn herbicide, it is rather weak on white clover. Perhaps
if you apply a strong dose of 2,4-D at least 3 times a year, you'll
burn back white clover, but you'll get your best results with a
different product, Drive.
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D: Drive is made by BASF, and it is the same as Paramount, that
is used in sorghum. Drive comes in a dry powder that must be mixed
in water to be applied. Use Drive at 1 pound per acre. If you are
mixing some up in a small handheld sprayer, put in 1 oz per gallon
of water.
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B: Drive has both contact and residual activity. This herbicide
also controls crabgrass, so almost everyone in the Midwest should
use this product on the lawn. The best time of year to apply Drive
is in late May in the upper Midwest, but it can be used anytime
white clover or crabgrass is actively growing.
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D: Turning to crop ground, white clover is rarely a problem in fields.
Tillage can reduce white clover pressure, but to completely knock
it out, you'll probably need Roundup or Touchdown. Since you're
dealing with a perennial weed, it is important to completely kill
the root system, besides the topgrowth. If you use Roundup or Touchdown,
be sure to apply at least 2 quarts per acre when the white clover
is actively growing.
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B: If you can't use Roundup or Touchdown in your situation, there
are some herbicides that can give moderate suppression. In corn,
Distinct and Hornet will each knock back white clover. In sorghum,
Paramount can be deadly to this weed, while in wheat, Curtail is
the best option. Finally, if you have white clover in conventional
soybeans, there's really nothing you can do other than tillage.
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D: In review, white clover can be beneficial or troublesome, depending
on your situation.
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B: It is easily identified when you find the white semi-circle on
each leaf.
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D: White clover is a creeping perennial weed that can fix nitrogen…
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B: and the best way to control it is to use Drive in lawns or Roundup
or Touchdown for cropland.
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10/21/01
