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Basics of Home Lawn Weed Control
Chemical Weed
Control
• Weed Control Terminology
Maintaining a dense, vigorous lawn is essential to prevent lawn weeds. Good
cultural practices account for 60 to 70 percent of turfgrass weed control.
Herbicides should be considered a supplement, not a stand-alone weed control
practice. If herbicide use is not accompanied by proper cultural practices, the
weed problem will return because the deficiency which led to the weed invasion
has not been corrected. When herbicides alone are used, the symptoms, not the
cause, of a weedy lawn are being treated.
Another point to consider is, how weed-free does your lawn have to be? Weeds
bother some people more than others. Step back and take a look. If the lawn
looks good from the street, do not waste your time going after those last few
weeds. Excess herbicide use designed to eliminate a few stubborn weeds does more
harm than good. A 100 percent weed-free lawn is not practical.
Chemical Weed Control
Using herbicides to control weeds in a home lawn is more complicated than it
would appear at first glance. When all the potential variables (weeds, lawn
grasses, timing, environmental conditions, herbicides, rates, and application
methods) are taken into consideration, it is possible to arrive at an infinite
number of situations. Some of the essentials for successful chemical weed
control are:
- Identify the weeds. Weed identification is often a
major hurdle because many homeowners are unfamiliar with
different types of lawn weeds. Help with weed identification is
available from the University of Arkansas Cooperative Extension
Service and local garden centers. If you have more than a casual
interest in plant identification, get a copy of Miscellaneous
Publication 169, Weeds of Arkansas, available from the
Cooperative Extension Service for $5. This publication contains
color photos of most common lawn weeds found in Arkansas.
- Choose an appropriate herbicide. After the problem
weed or weeds have been identified, the next step is deciding
which herbicide or combination of herbicides to use. After the
weed problem has been identified, the Herbicides for Home Lawns
table will assist in choosing a herbicide. Not all herbicides
registered for use on turfgrass are listed in this publication.
Several products are not packaged in sizes that are practical
for homeowners. Miscellaneous Publication 217, Turfgrass Weed
Control, contains additional information on turfgrass
herbicides. It is important to remember that no one herbicide
will control all weeds nor is there any one product that can be
used on all grasses in all situations. Consult the herbicide
table to locate the problem weed or weeds. Recommended products,
tolerant grasses, and use precautions are listed to the right of
the weed problem. Remember that the product label is the best
source of information as to which lawn grasses can be treated
with a particular product.
- Determine if the lawn grass will tolerate the herbicide
chosen. Some herbicides cannot be safely used on certain
grasses under any circumstances. For instance, MSMA should never
be used on St. Augustinegrass or centipedegrass. The safety of
other herbicides may depend on the growth stage of the grass as
well as many other factors. An example of this phenomenon is the
extra sensitivity of warm-season grasses to 2,4-D, dicamba, and
MCPP during the spring green-up period.
- Apply the herbicide at the right time. Good timing
takes into consideration the growth stage of the weeds, lawn
grass, and the environmental conditions at the time of
application. Examples of critical timing include treating
crabgrass with MSMA when it is very small or making sure
preemergence herbicides are applied before weeds begin to
germinate. The herbicide table includes application timing
recommendations.
- Apply herbicides accurately and uniformly. This is
often the most difficult step for most homeowners, since they
may not have ready access to proper application equipment.
Granular herbicides may be applied accurately with drop-type
fertilizer spreaders. Home gardeners typically apply liquid
herbicides with hose-end or pump-up sprayers. Suggested water
volumes are 4 to 6 gallons per 1,000 square feet of lawn surface
for hose-end sprayers and 2 to 4 gallons per 1,000 square feet
for pump-up sprayers. A third type of liquid applicator is the
lever operated backpack sprayer. While more expensive ($150 to
$250), these sprayers allow maintenance of constant pressure and
the use of a small boom to ensure uniform application. Consult
the product label for specific instructions as to spray volume.
Consult Miscellaneous Publication 216, Applying Herbicides to
Yards, Gardens and Other Small Areas, for further
information on application and calibration techniques
Weed Control Terminology
- Preemergence herbicide. A herbicide that is applied
to the lawn before weeds germinate and emerge. Preemergence
herbicides require about one-half inch of rainfall or irrigation
within 7 days of application to be effective.
- Postemergence herbicide. This herbicide is applied to
the foliage of weeds after they emerge. Annual weeds are more
readily controlled with postemergence herbicides when they are
small and actively growing.
- Green-up period. This is the time in the spring
and/or fall during which the grass is making the
transition from dormancy to active growth. Desirable grasses are
most sensitive to herbicides during this transition period.
- Non-selective herbicide. These herbicides will kill
all vegetation treated.
- RTU. Ready-to-use. This term is used to designate
products that do not require any additives or further dilution.
These are typically packaged in an aerosol or pump
applicator-container. An attractive feature of these products is
that they require no additional handling or mixing.
Back to Weed Control for Home Lawns
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