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Low maintenance lawns

Reducing pesticide use

By: Sandy Feather 2010
Penn State Extension


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.


The Environment

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.
 


Striving for Perfection

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.


Grass Seed Selection

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.


Cultural Management

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.

crabgrass
Seed heads on Crabgrass

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).


Dandelions & Broadleaf Weeds

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.


Keep the Mower Blade Sharp!

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.

sprinkler, lawn
Watering properly is critical

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 in western Pennsylvania 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.
 

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