Pests-On And In The Turf

A home lawn has all kinds of enemies. I've done my best in the preceding chapters to keep you from being your lawn's worst enemy, in so far as cultural practices are concerned. But that's only the beginning of the battle. In the course of a few seasons you may have to cope with a host of natural lawn enemies, including, 1. insects and animal pests, 2. fungus diseases, and 3. a variety of weeds. These three groups are discussed separately in this and the next two chapters.

Soil Insects—Beetle Grubs

Perhaps the best known of the lawn's enemies are not mature insects but grubs. If you are troubled by Japanese, Oriental or Asiatic beetles in your garden, you are likely to be troubled by their offspring in your lawn. These beetles lay eggs in grassy areas in late summer. The eggs hatch into larva, or grubs, which immediately start to feed on grass roots and continue until cold weather arrives. When the soil warms up in spring they resume feeding until they develop into beetles and emerge, usually during June.

The destruction wrought by a heavy infestation of Japanese beetle grubs in the lawn is difficult to imagine if you have not actually seen the effects of their feeding. Eating away at a depth of about an inch or two, these fat white pests will devour every root-hair they can find until finally the entire sod is cut off from its anchorage and can be rolled up like a carpet. Robbed of most of its roots, the grass often dies—especially when the root loss occurs during or just before the onslaught of summer heat. Yellowed or brown patches, in addition to loose sod, indicate where the grubs have dined.

The same general type of destruction can occur following the feeding of the grubs of May beetles or June bugs. The damage they do is not as dramatic as that of Japanese beetles, but for that very reason they may be all the more dangerous. They sap the vigor of the turf so it looks unthrifty, but the owner is likely to blame almost everything else before he discovers the grubs at work.

While Japanese beetles complete their life cycle in a single year, most species of May beetles or June bugs need three years to reach maturity, so the soil may contain three generations at the same time. The damage they do is more or less steady, with no peaks of activity, whereas Japanese beetles usually cause their worst damage in August, when the grubs are mature but have not gone dormant for the winter.

Grub Control

Many chemicals will kill these pests. The old standard controls (lead arsenate or calcium arsenate—10 pounds per 1,000 square feet) may be worth considering because these also have a repressive effect on the germination of crab grass seed (for a full discussion, see Chapter 14). While the treatment is fairly costly, it will last for five years. However, it goes to work very slowly. Do not expect to get the older grubs the same year the chemical is used. D.D.T., applied at the rate of about a pound of SO per cent wettable powder to 1,000 square feet of lawn, kills grubs about twice as fast. When applied in late fall or early spring, D.D.T. will not only kill all the young grubs but also about one-third of the adult brood of June bug larvae before they turn into beetles. A single application of D.D.T. made eight years ago is still effective in the oldest test I have observed.

Chlordane is even faster working, and less material is needed. Five ounces of 45 per cent emulsion, or 4 ounces of 72 per cent solution (both commonly available strengths) will treat 1,000 square feet if mixed with enough water to distribute them. In less than a month, 90 per cent of the adult grubs and all of the young grubs will be dead. One application can be expected to last five years.

Professional turf men use even more powerful chemicals—aldrin and dieldrin—but these are highly poisonous and must be used with great care. For long-range (but slow-starting) effectiveness, an application of milky disease spores is frequently recommended.

Other Pests

For many of you, the problem of beetle grubs may be just one of several, or may not be a problem at all. Here are some other common pests you may have to fight.

Ants are not particularly harmful to grass plants, but their mounds are unsightly on the lawn. A chlordane treatment will drive out ants.

Termites damage roots of some grasses along the Ohio River and for about 50 miles north of that line. Chlordane destroys them.

Sod Webworms, also known as tobacco crambids in the South, are often quite damaging to grass plants, feeding at the soil line in such an inconspicuous way that they can exist in a lawn for years without being detected. They cause a vague yellowing that is often mistaken for lack of nitrogen. Chlordane will eliminate them.

Chinch Bugs are often serious  pests in turf. Although not strictly soil insects, they are destroyed by the same chlordane treatment used for soil-inhabiting pests. However, once the control chemical has been washed down into the soil it is no longer effective against chinch bugs. If they invade the lawn a second year after treatment, a light surface spraying of chlordane (1 pint of 72 per cent solution to 5,000 square feet in 50 gallons of water) should control them.

Earthworms, as everyone may not know, are usually active throughout the year. Cold drives them deep into the soil until snow comes. If the snow is sufficiently heavy and lasting, the soil temperature will gradually rise until it reaches 33 degrees; at this point the worms resume feeding.

Under a snow cover, both common earthworms and night crawlers have a holiday. Safe from birds they work all winter long, burrowing through the soil for organic matter and coming to the surface to deposit their castings. A heavy worm population will "quilt" the soil surface so extensively that the effect may be mistaken for frost heaving.

Earthworm Fallacy

Treatments which control other soil insects will also get rid of these pests, with considerable benefit to the health of the turf. Although there are "earthworm fans" who insist that these wriggling creatures are necessary for rich soil, in my estimation this is poppycock. Earthworms will only live in rich soil, and if it is really rich they cannot contribute anything to it.

No one has yet been able to show me how earthworms can possibly contribute anything to soil fertility (other than distributing it from one point to another). They require nutrients to keep alive, which they digest out of the soil, excreting the residues. True, when they die their bodies decay and return a smidgin of organic matter to the mass of the soil. However, this must necessarily be less than the amount they consumed.

Moles are naturally part of any discussion of earthworms and beetle grubs: the two problems are interrelated. Irate lawn-owners wonder why moles are so persistent in pushing their noses through yard after yard of soil, heaving up the sod into unsightly ridges. They are after food. Soil insects form the diet of the mole. High on the list of mole delicacies are earthworms, white grubs and other larger insects. Destroy these pests and the moles will travel on to richer fields.

Land Crabs, while not common, can be one of the most irritating and mysterious problems in a lawn. You'll know you have this problem if you find holes that have a little dirt at the mouth, but that otherwise seem to go so deep in the soil that you'll wonder where the rest of the earth went. Usually the holes have water in the bottom. These holes are the openings of the burrows of land crabs (crayfish), and they usually appear in lawns made on filled land over old swampy places. A tablespoonful of rotenone in a quart or so of water—with a small quantity poured into each burrow— should end this nuisance in a hurry.

Mushroom and Toadstools are minor annoyances, but they dismay thousands of lawn-owners annually. They are above-ground evidence of a fungus mycelium which is living on buried organic matter, usually a dead stump or other wood. Heavy rainfall or watering encourages the condition. Mowing won't kill them because the mushroom are only the fruiting bodies. The mycelium is too deeply buried to be easily killed by chemicals. If the dead wood can be exposed, dusting with sulfur will make it uninhabitable by the fungus.

Old-time books (and some new ones!) recommend spraying the toadstools with Bordeaux mixture, but I have never found that this does much good. A mercury disinfectant will kill the mycelium, but the cost will be prohibitive if the affected area is large.

Dogs can be a real nuisance. Even dog-lovers turn against them when they make a mess of lawns. The usual chemical repellents do practically no good on an area as extensive as a lawn. My remedy is a boy's beebee gun or air rifle. This throws a small pellet that will sting but not seriously injure the animal. A generous dusting with sulfur sometimes kills doggy odors that keep dogs coming back to an area, but this is not universally successful. Sewerage sludge seems to lure dogs to a lawn like bees to sugar water.

Chips Off The Chapter

1. One of the most damaging lawn insects is not an insect but a stage the grub—of a variety of beetles. Perhaps the worst in many parts of the country—certainly one of the best known—is the Japanese beetle grub. With modern chemicals, however, you need not endure these marauders.
2. A number of effective controls are also available for other lawn pests.
3. Earthworm "value"—an old wives' tale.
4. When you kill off the grub population, you protect your lawn against mole invasions, too.
5. Toadstools rarely are a cause for concern. Dogs often are, but there's not much you can do about them.

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