The most destructive of all lawn pests are insects. Unlike fungus diseases which damage only small portions of the lawn, or weeds, which we can tolerate temporarily, some insects are so dangerous that they must be eradicated soon after they are detected in the lawn.
Effective Chemical Insecticides
Several effective chemical insecticides are available for this purpose. Though expensive, lead arsenate has been used for many years to control Japanese beetle grubs and other insects.
But DDT and Chlordane, two other chemicals, will kill most lawn insects quicker at less expense and with little or no damage to the turf.
Like lead arsenate, they will prevent further inroads of grubs, but not other insects, for five years after application and possibly longer.
All three can be applied dry, as dust, or in solution, as sprays. In addition to these three chemicals, there are other useful insecticides, but only a little is known about how long they will be effective in the soil against grubs in future years.
DDT and Chlordane can be purchased in different formulations and under many trade names. However, all formulations are effective, provided the correct rate is used; this is frequently given on the container for Japanese beetle grubs.
Lead arsenate is purchased as a relatively pure chemical and is applied at 10 pounds per 1,000’ square feet for these grubs.
Sometimes rates are not given on DDT and Chlordane containers. In this event, an effective rate for grubs of Japanese beetle for DDT is 10 ounces, and for Chlordane, four ounces of pure chemical per 1,000’ square feet. Some arithmetic is involved here.
If, for example, one obtains a 25% percent DDT wettable powder, the amount to apply per 1,000’ square feet would be 40 ounces or two pounds eight ounces, and if one were using a 10% percent, DDT Dust, the rate would be 100 ounces, or six pounds four ounces,
A 40% percent Chlordane wettable powder would be applied at 10 ounces, and a five percent Chlordane dust at 80 ounces or five pounds per 1,000’ square feet.
Volume Measurements
When using a liquid material, you make the same calculation. It may be difficult to weigh out the amount you require.
In this event, use one of the following volume measurements:
1 pint = 2 cupfuls = 10 fluid ounces = 32 tablespoonfuls.
To say it another way around: 2 Tablespoonfuls = 1 ounce.
Handle It With Care
When using any chemical turf insecticide, the homeowner is cautioned to handle it carefully because it is also poisonous to him to a greater or lesser degree.
Gloves should be worn because the chemical will penetrate small cuts on the hand and under the fingernails. Face masks or respirators are also available.
And wearing one when spreading an insecticide is a reasonable precaution. Keep children and animals off the lawn until the chemical has been watered in, and store it out of reach of children.
Some insecticides are poisonous to cold-blooded animals such as fish, and care should be taken not to let the chemicals run into fish ponds bordering the lawn.
Lead arsenate, DDT, and Chlordane can be purchased as dust. This is a convenient form to apply them to small turf areas.
A fertilizer spreader can be utilized for this purpose. If unavailable, the material can be mixed with a convenient amount of dry soil, sand, or organic fertilizer and broadcast by hand over the lawn.
The chemical must be thoroughly mixed with the carrier. A pailful of carriers is a convenient amount to use per 1,000’ square feet. Evenness of spread is required for effective results.
Wettable powders of DDT and Chlordane are soluble in water, and these materials can be sprayed onto lawns if one owns or can borrow a sprayer.
If obtained in a form containing a demodulator, lead arsenate can also be sprayed onto the area as a suspension.
Twenty-five gallons per 1,000’ square feet is the recommended amount of water for these three chemicals when applying them as sprays at these rates.
Thorough Watering
It is most important that a thorough watering follow the application of either dust or sprays to increase penetration and minimize bird injury.
If water is unavailable for the lawn, it is often possible to time applications to precede rain.
In many localities, one can have the job done by commercial spray companies that use power sprayers. These companies will often give a guarantee with the job that the insects will be eradicated.
In this regard, Chlordane materials, under average soil conditions in the growing season, will start to kill Japanese Beetle grubs in 2 to 4 weeks, DDT in 6 to 8 weeks, and lead arsenate in about 12 weeks.
This timing is, of course, very variable and is influenced by many factors. Spraying companies can be located through the local arborist.
The homeowner must check his lawn periodically for grubs and other insects throughout the growing season.
Earthworms also may become too much of a good thing, but whenever possible, they should be left in the lawn where they do a wonderful job of aeration.
The Tropical Earth-worn, or Stinkworm, recently arrived in this country and has been found since in New Jersey, New York, and Connecticut. It appears in great numbers, causing so many earth casts that it is almost always necessary to eradicate.
44659 by Geoffrey S. Cornish