How to Maintain a Chemical-Free Lawn
A great deal can be done to deter pests, much of it going back to the elemental roots of gardening
Before declaring chemical warfare on your lawn, consider whether you have taken all possible steps to make your property inhospitable to pests. A great deal can be done to deter pests, much of it going back to the elemental roots of gardening. Following are a few the basic considerations:
Provide healthy soil. A nutrient-rich layer of topsoil, 5 to 6 inches deep, is critical first step. If your yard has less than this, consider adding composted manure (free of weed seeds) across an existing lawn, but not so much as to smother it. In addition to organic compost, the Environmental Protection Agency suggests grass clippings, bone meal, cottonseed meal or dried blood, which release vital nutrients into the soil without destroying natural microorganisms and earthworms vital to its well-being. Warns the EPA: "Quick-release chemical fertilizers can brown the grass, induce pest infestations, increase thatch buildup and promote leaf growth at the expense of healthy root growth, leaving the grass susceptible to summer heat, drought, disease and compaction."
Test the soil for any imbalance in alkalinity or acidity—the so-called pH balance. If it is excessively acidic, add lime. If too alkaline, add sulphur and perhaps gypsum, depending upon your region. The tendency is toward acidity in the East and alkalinity in the West. Consult your county's cooperative extension office for information about your area.
Use care in selecting grasses. Plant grass varieties that are right for your particular climate and condition. According to the National Coalition Against the Misuse of Pesticides (NCAMP), a mix of grasses offers better protection against pests and disease than a pure stand. Because of profound regional variations, ask your county extension office for the optimum mix. In some instances, planting additional seeds among established lawns can reduce weed infestation and repair damage.
Maintain the lawn properly. Always make sure that your mower's blade is sharp. A dull blade leaves an uneven cut, which can retard grass recovery and expose grass to loss of moisture. Never give your lawn a butch cut. Grass that is cut too short becomes more vulnerable to stress from heat and drought. Cutting the grass too short also allows too much light to get to the soil, enabling weeds—especially crabgrass—to prosper. NCAMP recommends setting the mower blades as high as possible, though of course the proper height depends on the variety of grass. To avoid unnecessary stress to the lawn, do not mow in the heat of the day. Prevent excessive buildup of thatch, the grass stems and roots that accumulate just below the surface and can promote pest infestation.
Depending upon the region and character of the lawn, the EPA suggests applying organic matter or gypsum, then watering it to help release the gypsum. This helps reduce alkalinity and makes a better growing medium for turf. Avoid over-watering the lawn, as excessive moisture can lead to shallow root systems and disease-prone lawns. Where soils are compacted, aeration (the removal of cores of soil) may be helpful. Aeration allows air, water and nutrients to seep in, promoting healthy root growth. The best natural aerators are ants and earthworms—often the first victims of pesticides.
Monitor for pests. The most important step in effective lawn maintenance is watching regularly for trouble to keep small problems from becoming big ones.
Check the lawn at least once a week, keeping an eye out for signs of insect, fungus or weed infestation. Weeds can be removed by hand and controlled to some extent by mowing. If an herbicide is called for, select one that is least toxic, such as a fatty-acid soap. If the problem is insects, first identify the species. For the white grub of the Japanese beetle, NCAMP recommends milky spore bacteria, a naturally occurring insect disease. For chinch bugs, try using a wash of insecticidal soap over the thatch.
Sheila Daar, director of the Bio-Integral Resource Center in Berkeley, California, offers some additional tips on how to recognize and deal with yard pests. In many parts of the country, she explains, insects don't become active until the soil temperature rises above 50 degrees F She suggests that homeowners buy a soil thermometer and stick it into the ground next to the sidewalk for easy access. When the soil temperature hits 50, "start looking for suspicious browning of the lawn or other signs of trouble."
If you see a suspicious spot, mix a couple tablespoons of detergent in a gallon of water and pour the concoction over the spot. "This will force the pests up to the surface where you can count them," says Daar. If the problem is white grubs, cut a flap in the lawn and count the larvae. "It's a numbers game," she says. "The lawn can tolerate a certain number of pests. It's all a question of how healthy the lawn is."
Homeowners struggling to keep up with the Joneses might keep in mind that, in general, "the most heavily managed lawns—golf courses, for example—are usually the ones with the biggest pest problems," says. Daar. Applications of chemical pesticides kill off susceptible organisms, often starting with the beneficial ones, she says. Pest species, however, often develop resistance and continue to reproduce, requiring more frequent applications, higher doses and stronger chemicals—a cycle called the pesticide treadmill.
The Bio-Integral Resource Center publishes brochures with tips on lawn care and pest control. For a copy of the "Least Toxic Pest Management Publications Catalog," send $1 to: P.O. Box 7414, Berkeley, California 94707