Articles & Resources

Maintaining a Healthy, Organic Lawn
by Gail Robinson, Director of Horticulture

Even in a well-maintained organic lawn, problems can arise. Once you've determined the cause of your problem, there are usually a number of environmentally-friendly ways to deal with them so resist the temptation to pull out a bottle of fungicide or insecticide. Though weeds, diseases, and insect infestations are problems, they're also indicative of trouble within the lawn's natural ecosystem. Short- and long-term organic solutions are the safest way to keep your lawn-and yourself-healthy.

Prevention is the key to not having lawn problems to begin with. The following suggestions can reduce the risk of getting a lawn disease:

• Follow a well-balance fertilization program minimizing excessive application of nitrogen before the onset of hot weather
• Water less often, but deeply rather than frequently and shallowly
• Water early in the day to promote rapid drying of the leaf blades
• Do not fertilize in late fall since it will stimulate new growth at the wrong time.
• Do not leave plant debris and matted leaves on the grass
• Continue to mow the lawn in the fall as long as it is growing
• Mow frequently, but only when the grass is dry to minimize the spread of disease
• Sow relatively disease resistant grass like Kentucky bluegrasses
• Remove thatch that is in excess of 1 ½ inches thick and improve drainage

Both drought and excessive wet weather promote disease which is out of our control, but by observing the condition of your lawn and by following the above suggestions you have a better chance of maintaining a healthy and beautiful lawn.

In researching to write this article, I found an extremely helpful and most thorough and well organized article entitled "Common Diseases and Problems on Home Lawns" by Dr. Sharon M. Douglas from the Department of Plant Pathology and Ecology at the Connecticut Agricultural Experiment Station in New Haven, CT online.

Dr. Sharon's article should be read if you suspect you have a lawn disease. The following is a list of the symptoms your lawn might have that would indicate a problem:

• Circular to irregular patches of poorly growing grasses that eventually turn brown
• Mold on grass that appears white to salmon in color, or white to gray
• Small circular brown spots on the leaf blades that can turn nearly white
• Blades appearing covered with a pinkish, gelatinous growth when wet
• Small red to purple spots on leaf blades to tip
• Small slimy "greasy" spots in the lawn which appear cottony when wet
• Circular patches appearing brown or black and rotted
• An erupting leaf surface revealing rusty orange-colored spores

Below are some additional indicators of an unhealthy lawn along with some simple steps you can take to solve them without using harsh insecticides, fungicides and other treatments that have a negative impact on our environment long-term.

Yellow Grass
Yellow grass may indicate wear and tear, an iron or nitrogen deficiency, or that the grass is going dormant. Before attempting to treat it, get your soil tested to determine whether organic soil amendments will green up the grass.

If your yellow grass is related to a pest infestation, billbugs or chinch bugs are most likely the culprit. Billbugs lay eggs in grass, and their larvae feed on stems, causing yellow circular patches that appear drought-stressed. Chinch bugs suck the sap from grass which causes yellow circular patches to develop. To treat for billbug or chinch bugs, add organic matter and water the lawn well for 3-4 weeks to a depth of 6 inches. To prevent these pests in the future, reseed or overseed the lawn with resistant endophyte-enhanced grasses. (Check seed package labels for these special varieties.)

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Bare Patches
Bare patches can be caused by heavy foot traffic or dog waste. If that isn't the case with your lawn, armyworms may be the cause and you'll be able to see the pests eating your grass. Armyworm larvae chew grass blades down to the crown, especially during cool, wet weather. Apply a solution of parasitic nematodes to the infested area; then water well. Bacillus thuringiensis (BT) is effective when the larvae are small. To prevent armyworms in the future, rake out dead grass and reseed with endophyte-enhanced varieties.

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Red Grass
Red Grass is a good indicator of disease but fortunately, is easily diagnosed and treatable. Red thread, a fungus that occurs during cool, wet weather, causes circular patches of dried grass. To solve red thread, mow regularly to remove infected blade tips, and apply compost. To prevent red thread in the future, water deeply and provide regular, adequate nitrogen by leaving the grass clippings on the lawn.

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If your red grass is due to rust, reddish spores will appear. Rust is a fungus afflicting drought-stressed, nutrient-starved lawns. To treat, mow regularly to remove infected blade tips, and leave grass clippings on the lawn. To prevent rust in the future, avoid night watering, which causes a prime damp environment for spores to grow.

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White Grass
White grass is a sign of powdery mildew, which causes small patches of white or gray fungus on grass and is most common in shady, wet areas and on over fertilized lawns. To treat powdery mildew, spray a solution of one part milk to nine parts water over affected areas. To prevent it in the future, avoid over fertilizing and over watering the lawn, and plant shade-tolerant grass in areas that get only partial sun.

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Brown Grass
Brown grass is often a result of poor maintenance, site conditions, or summer dormancy rather than a pest infestation or disease. Be sure your lawn isn't being mowed too short and that it is not suffering from soil compaction, drought, or nutrient deficiencies.

If it's more than poor maintenance, you may have white grubs. White grubs chew on grass roots, causing irregular, brown, dead patches in the lawn. To get rid of white grubs, apply parasitic nematodes (genus Heterorhabditis) to the affected area; then water well. To prevent white grubs in the future, apply milky disease spores, which parasitize Japanese beetle grubs and survive for several years.

Sod webworms can also cause brown, dead spots by severing grass blades. They prefer new lawns. To treat sod webworms, apply BTK about two weeks after moths appear, when pests are in their larval stage. If the problem persists, overseed with endophyte-enhanced grass varieties.

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Shabby, Worn-Out Looking Lawn
If your lawn looks weak but you can't identify the cause, check the depth of thatch. Thatch, a springy mat of grass roots and stems on the soil surface, is the result of excess fertilizer use. It is not caused by letting clippings fall onto the lawn. Less than a half inch of thatch acts like mulch. A deeper layer keeps water and nutrients from reaching the grass roots.

Scrape out the thatch with a hard-tined rake. To prevent thatch in the future, spread a layer of compost on top of the soil to encourage earthworms to thrive in the soil and break down the thatch layer at the same rate at which it is being formed. Use slow-release organic fertilizers only.

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Mushrooms
Mushrooms are among the most difficult of lawn problems to get rid of since they are signs of a fungal mat under the soil that grows outward. Fairy rings appear in the grass first as dark green circles, eventually sprouting mushrooms that can deplete the soil's nutrients and form a water-repellent mat, causing the grass to die. Dig out the mushrooms and turn the soil to a depth of 2 feet, mixing in compost as you go, to break up the fungal mat and improve the soil's fertility.

To prevent this in the future, use good maintenance practices, such as discouraging thatch buildup by using only slow-release fertilizers, and watering deeply no more than once a week instead of giving your lawn frequent shallow sprinklings.

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Moss
Low-growing, soft patches of green spongy growth are particularly common in shady areas. Moss takes hold in poorly drained sites, often where the soil is acidic. Rake off the moss and add compost to improve drainage. Reseed bare areas. If moss is persistent, plant a groundcover that thrives in damp, shady spots, such as violets or ajuga.

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Dirt Mounds
Mounds of dirt in your lawn are usually an indicator of a problem underground. Moles tunnel through your lawn to feed on grubs and earthworms, creating ridges and mounds. Press mole ridges flat with the head of a rake to restore the roots' contact with the soil
To prevent moles in the future, remove the food source, and the moles will seek it out elsewhere. In the case of grubs (see "Brown grass"), the best long-term control comes from milky disease spores, which come in a liquid form you apply as a drench to the soil.

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Weeds
Although nobody likes the look of them, a few weeds are perfectly normal in an organic lawn. But a particular weed overtaking your grass is a sign your lawn isn't competitive enough, and you need to discover why in order to modify your lawn-care practices.

Clover, which pulls nitrogen from the air, appears where grass is sparse and the soil is low in nitrogen. Till soil to remove clover; then add compost to the soil to increase its fertility. Reseed bare spots with grass. To prevent clover, apply a slow-release organic lawn fertilizer in fall and leave clippings on the grass all season.

Dandelions can appear anywhere in your lawn, especially where turfgrass is weaker. Remove flower heads before they go to seed and dig out roots with a dandelion weeder. To prevent dandelions, apply corn-gluten meal (a natural "weed and feed") in early spring.

Crabgrass can sprout if you mow the lawn too short, allowing sunlight to germinate the weed's seeds. Dig plants out completely before they set seed, and sow grass seed in their place. To prevent crabgrass, raise your mower's blade to the highest setting and keep removing weeds from reseeded spots until new grass is established.

Broadleaf plantain appears in compacted soil and anywhere grass has a hard time growing. Pull plants out with a dandelion weeder and reseed with grass. To prevent it, add compost to loosen the soil, discouraging the weed from returning.

www.gardensalive.com is a good source of high-quality, organic lawn and garden care products.