Something wrong out there on the lawn? Time to do some trouble-shooting.
Rounding up the usual suspects will narrow the field of causes down to:
* Not enough water? This one's most likely, for sure, especially in the West.
* Wrong grass for the site? Maybe.
* Insects? Possible, especially midsummer.
* Diseases? Possible, especially a few weeks after a heavy fertilizing.
A lawn that is watered deeply, properly fertilized, and mowed a little on the long side will be able to fend off much common adversity.
Poor maintenance is responsible for thatch (too much nitrogen fertilizer, shallow watering) and stress caused by poor mowing practices or inadequate watering. Rake thatch out with a hand or power rake. Compacted soil may be responsible for poor water and fertilizer penetration, resulting in thin and uneven lawns. Aerators can be rented for do-it-yourselfers or the task can be contracted to a landscaper.
One common problem is having the wrong grass for the site, such as a Kentucky bluegrass in Phoenix, or Bermuda grass in deep shade. Overseeding bluegrass with more heat-tolerant tall fescue or replacing Bermuda grass with St. Augustine grass or zoysiagrass are the solutions.
With a couple of exceptions, insect infestations rarely demolish a lawn. Some exceptions are sod webworms, grubs, and chinch bugs.
Sod webworm damage shows up in late spring as small dead patches in an otherwise healthy lawn. They chew off the blades of grass near ground level. Check at night for a light brown caterpillar about an inch long. Bt is a remedy.
Grubs are larvae of beetles. When they have done their damage you can roll entire patches of lawn back like a carpet. One sign of grubs in a lawn is the presence of a lot of one-inch holes in the lawn where birds, skunks, or raccoons have been digging for a meal of grubs. Some grubs emerge from the soil as Japanese beetles, which attack gardens. Milky spore or beneficial nematodes are the remedy.
Chinch bugs are fond of St. Augustine grass, but will attack bluegrass and bentgrasses, too. Damage shows up as large, distinct patches.
A good remedy for solving insect problems is to collect a few in a bottle (you may need to go out with a magnifying glass, or at night) and take them to the cooperative extension service at your state university or to a garden center for identification. Learn all your options. Organic treatments are available for almost every problem.
Most lawn diseases shown up during periods of warm and moist weather. In the North, snow mold causes tan or gray patches to show up early in spring under snowbanks that are slow to melt.
While insect damage often shows up as foliage that is chewed, lawn diseases are usually a form of fungus that shows up as gray, tan, brown, or black spots or damage on the blades. Poor fertilization, mowing, and watering practices contribute to some diseases.
They can be difficult to identify specifically, so it may be necessary to take a sample to your garden center to determine a course of action.
Photography by Susanne DeJohn/National Gardening Association.