I have received a number of questions
regarding how to grow a decent lawn without using a lot of
pesticides. Here is a primer on best management practices:
Environmental advocates often criticize
lawns as requiring too much pesticide and fertilizer use, which can
run off into streams and rivers, resulting in pollution of those
environments. It is true that some people manage their lawns very
intensively in order to have the best lawn on the block, and may use
too many inputs to achieve the desired result. However, it does not
have to be that way. You can have a very nice lawn without making
frequent fertilizer or pesticide applications as long as you can
tolerate a spot or a weed or two. Remember that sports turf such as
a golf course does need to be as perfect as possible. A weed or spot
of insect or disease damage affects the play of the ball, or could
cause a career-ending injury to an athlete. Fortunately, home lawns
do not need to strive for such perfection - it is not likely that
the Masters will be played in your yard in the near future!
You don't HAVE to do anything to your lawn
except keep it mowed to comply with local ordinances. The resulting
lawn may not be perfect, but it is green and tolerates foot traffic.
If you have children or pets, there is no substitute for a lawn that
will tolerate the kind of wear and tear that grass does. Lawns have
added benefits of cooling the ambient air temperature around our
homes; absorbing rainwater that otherwise would run off and cause
erosion or even flooding; protecting streams and other bodies of
water from pollution caused by runoff; allowing rainwater to slowly
infiltrate the soil, recharging groundwater supplies; improving air
quality by reducing dust; and helping to reduce noise levels by
deadening sounds.
Low maintenance lawns start with selecting
the proper type of grass for our climate and the cultural realities
of your yard. If you have a lot of shade, make sure to use a mixture
that has a predominance of fine fescues.
These are the most shade-tolerant species of
the cool season grasses grown in our part of the United States. If
you have a lot of sun, dwarf or turf-type tall fescues, or a mixture
of Kentucky bluegrass and perennial ryegrass will perform best.
Dwarf tall fescue also tolerates partial shade.
Proper cultural management of your lawn will
go a long way toward improving its health and appearance without
using a lot of pesticides. You may need to make a few herbicide
applications to get severe
weed infestations under control. Once you
have accomplished that, you can control the occasional weed by hand
pulling or spot treating with a liquid herbicide. There is no reason
to spray herbicides over the entire lawn when there are not many
weeds. If weeds are not a major problem in your lawn, or if you do
not mind them, skip down past the weed control information and
concentrate on the cultural information that follows.
Annual grassy weeds such as crabgrass are
generally controlled with pre-emergent herbicides such as Halts (pendimethalin),
Dimension (dithiopyr) and Barricade (prodiamine). If your lawn has
been under a pre-emergent regimen for a number of years and is
relatively lush and thick, you may be able to spot treat areas where
crabgrass is most likely to grow, rather than broadcasting
pre-emergent over your entire lawn. Crabgrass is most likely to grow
in the crevices between the lawn and hardscape, such as along
sidewalks and driveways, or any areas where the grass has thinned
out. You can also switch to a more natural alternative such as corn
gluten meal. Although corn gluten meal is not as effective as
synthetic pre-emergent herbicides at first, it seems to provide
better control once you have been using it for three or four
consecutive years. You should have your pre-emergent herbicides in
place when forsythia is in bloom. You can also take a wait and see
approach, and control crabgrass just after it germinates with a
post-emergent product such as Ortho Weed-B-Gon Crabgrass Killer
(calcium acid methanearsonate).
Start controlling broadleaf weeds such as
dandelions and plantain as soon as they start actively growing.
Liquid broadleaf weed killers are generally more effective than
granular weed and feed products.
They have the added benefit of allowing you
to make additional applications to tough to control weeds such as
clover and ground ivy. You cannot make additional applications of
weed and feed because that much fertilizer would burn your lawn.
Herbicides labeled for home lawn use generally contain a combination
of 2,4-D, MCPP and dicamba. You often get the best control of tough
weeds by making herbicide applications in late summer (mid-August to
early September). You still may need two or three applications to
get sufficient control. Check the label of the herbicide you are
using for suggested application intervals. Even though some of these
weeds seem indestructible, keep after them and repeat your
applications at the shortest recommended intervals until you are
satisfied with the level of control. Now you can focus on proper
maintenance practices to help the lawn outgrow the weeds and
minimize the need for herbicide applications.
Mowing practices greatly determine the
quality of turfgrass. If you allow your lawn to grow long, then cut
it short, you stress the grass by depleting the carbohydrate
reserves stored in the crown and roots of the individual grass
plants. This can make your lawn more susceptible to attack by insect
and disease problems. Most species of turfgrass should be cut at a
height of two-and-a-half to three inches. There is a direct
relationship between the height of cut and the depth and extent of
the root system. The longer the grass, the more extensive the root
system. The shorter you cut it, the less root system it will have.
Since summer heat and drought are the most stressful for the cool
season grasses we grow, leaving the grass longer to encourage an
extensive root system will make your lawn more drought tolerant.
Leaving the grass longer also shades the soil, moderating soil
temperatures and helping to conserve soil moisture. Longer grass
also shades out germinating weed seeds and crowds out weeds that try
to become established. Try not to remove more than one-third of the
blade of grass in one mowing. How often you should mow depends on
how fast the grass is growing.
Be sure to
sharpen your mower blade
regularly. A sharp mower blade makes a clean cut that the grass
recovers from easily. Dull mower blades shred the grass, making
jagged wounds that are harder to heal. They can serve as a point of
entry for insect and disease problems. How often you should sharpen
your mower blade depends on the size of your lawn and the number of
obstacles it is likely to encounter. Once a month for very large (or
obstacle-filled) lawns or every other month should be sufficient.
Small lawns can get by with sharpening once a year.
Deep, infrequent watering during hot, dry
weather is important to maintain a healthy lawn. Deep watering
encourages the turf to develop a deeper, more extensive root system.
Conversely, frequent, shallow watering encourages a shallow root
system. A shallow root system means a lawn that is under drought
stress when the top couple of inches of soil dry out. Use a
sprinkler or an irrigation system to apply one to two inches of
water weekly to your lawn if we are not receiving any rain. This is
best applied in one long, deep soaking session, rather than
watering
your lawn a little bit every day. Our clay soils can only absorb
about one-half an inch of water an hour, so it should take two hours
of watering to apply an inch of water. To measure how long you have
to run your sprinkler or irrigation system, take a flat-bottomed
container such as a coffee can and mark off half-inch increments.
Place the can or cans where it will be hit by the water, and time
how long it takes to gather one-half inch of water. Then run your
sprinkler twice as long. You may need to apply water even slower to
steep slopes to avoid wasting water to runoff. It is best to water
in the morning.
If you water during the heat of the day, too
much water is lost to evaporation. If you water at night, the grass
stays wet too long, and may be more likely to have disease problems.
You also have the option of allowing your lawn to go dormant during
hot, dry weather.
