Lawn Care Without Pesticides
The lawn is a very prominent and important part of the home landscape. Aside from its attractive looks, the lawn has many other benefits - it improves air quality around your home, it reduces noise, and it works like an air conditioner by cooling your property in the summer. Perhaps this is why Americans spend billions of dollars annually maintaining their lawns. In recent years, however, the American public has become much more concerned about the use of pesticides in the home landscape. Can home lawns be maintained without pesticides? Yes they can, and they may even look nice too, if some very basic lawn care principles are followed.
First, you will have to have a realistic perception of what a pesticide-free program will produce. There is no panacea. You may see weeds and an occasional dead area in the lawn. Problems such as these, however, can be kept to a minimum through proper culture. A lawn that is properly maintained will be vigorous, healthy, and much more tolerant of disease and insects.
Cultural Management
Selecting the Proper Grass
The first step to having a nice lawn without pesticides is two select the proper species and cultivars for the site. Several grass species can be used for home lawns in New York State. Species and even varieties will differ in their appearance, their adaptation, and their ability to tolerate diseases and insects.
Cornell University annually publishes a list of recommended turfgrass species and cultivars. Contact Cornell Cooperative Extension - Suffolk County when planning any new lawn seedings.
Kentucky Bluegrasses
Kentucky bluegrass is the lawn grass species best adapted to New York State conditions. The newer, improved cultivars are very attractive and survive extremes in temperature and drought. Kentucky bluegrass is a true sod-forming grass because it spreads by underground stems. Thus, it has the ability to fill in areas of the lawn that may be damaged by pests.
Most new bluegrass cultivars have good to excellent resistance to leaf spot, one of the more common diseases on bluegrass lawns. Likewise, cultivars differ in there resistance to other diseases such as Summer Patch. Use a blend of at least three bluegrass varieties for home lawns to maximize the lawn's resistance to diseases.
Perennial Ryegrass
Perennial ryegrass is a common component of lawn seed mixtures. Improved ryegrass cultivars are very attractive, and are compatible in mixtures with Kentucky bluegrass. Perennial ryegrass is susceptible to winter injury, so it should only be seeded in mixtures with Kentucky bluegrass in upstate New York.
Like Kentucky bluegrass, perennial ryegrass cultivars vary in their tolerance to diseases. As a whole, perennial ryegrasses have excellent resistance to Summer Patch and should be included in a seed mixture where patch diseases are a problem. Also, the ryegrass cultivars Repell, All*Star, Citation II, Dasher II, Pinnacle, Saturn and Pennant have resistance to surface feeding insects like sod webworms and chinch bugs.
Perennial ryegrass is much more vigorous in the seedling stage than Kentucky bluegrass. Therefore, it may be included in a lawn seed mixture with Kentucky bluegrass provided that it does not exceed 20%, by weight, of the seed mixture.
Fine Fescues
Fine fescues are a group of grass species that includes creeping red, chewings, and hard fescue. The fine fescues are excellent low-maintenance grasses in that they do well under low fertility and moisture. They are very fine textured and will produce an attractive turf cover if properly installed and maintained. Fine fescues are quite tolerant of shade. Use fine fescues alone or in mixtures with shade-tolerant bluegrasses for shaded lawns.
Fine fescues have a few disease problems such as red thread and dollar spot. Select cultivars resistant to these diseases; including Spartan, Waldina, Bighorn, Reliant, Scaldis, Aurora, SR3000, and Biljart. New cultivars with resistance to surface feeding insects are now available and include SR3000 and Jamestown II.
Tall Fescue
Tall fescue is another good low-maintenance grass. It does well under low fertility and moisture, and has few disease problems. Tall fescue is much coarser textured than the other cool-season lawn grass species. However, the improved "turf-type" tall fescues are finer textured than old varieties and will produce an attractive lawn if installed properly.
Tall fescue does not survive harsh winters very well. Therefore it is not recommended for lawns north of Westchester and Orange Counties, except in areas close to Lakes Erie and Ontario. Also, tall fescue is not compatible with other grasses. Therefore, it should be seeded only as a monostand, that is, with no other grass species.
Fertilization
A properly fertilized lawn will need fewer pesticides. Soil pH and fertility, especially nitrogen and potassium influences a lawn's ability to resist turfgrass pests. Soil testing is the first step in determining fertilizer requirements of a lawn. Contact Cornell Cooperative Extension - Suffolk County for information on having soil tested.
The soil pH should be maintained in a range of 6.0-7.0. Plant nutrients are more available and beneficial microorganisms are more active within this range. Apply lime or sulfur according to soil test recommendations to modify the pH. Nitrogen and potassium are needed in moderate amounts for a pest-resistant lawn. Returning the clippings after mowing can reduce these requirements by 30%. Kentucky bluegrass lawns will require 2 to 3 pounds of actual nitrogen and 1 to 3 pounds of potash per 1,000 square feet per year, split into two or three applications. Fine fescues and tall fescue lawns will require 1 to 2 pounds of nitrogen and 1 to 3 pounds of potash per 1,000 square feet per year.
Lawns should be fertilized two or three times per year. If fertilized twice it should be done in the spring and early fall. If fertilized three times annually, it should be done in late spring, early fall and late fall. Slow-release fertilizer sources such as sulfur-coated urea or natural organics will provide more uniform release of nitrogen. The lawn will be greener for a longer period of time, and top growth won't be excessive. Some natural organic products will also suppress disease.
Mowing
Proper mowing will discourage weeds, and make the lawn more resistant to pests. Proper mowing involves mowing at the correct height and frequency. Mowing height will affect the size of the root system. The shorter the mowing eight, the shallower the root system will be. The lawn will then be more susceptible to drought injury, and less tolerant of root feeding insects and root pruning disease. Also, lawns mowed too short will allow more weed seed germination, making the lawn much more prone to weed invasion.
Mow Kentucky bluegrass and fine fescue lawns at 2 to 3 inches. Tall fescue lawns should be mowed at 3 inches.
Proper mowing also means mowing at regular intervals. The rule of thumb is as follows: Never remove more than one-third of the leaf tissue with each mowing. Scalping the lawn can shock it, making it more susceptible to stress.
Lawn mowers should be kept sharp. Dull mowers leave wounds on the grass blade that serve as a point of entry for diseases. Leaf spot is especially encouraged by dull mower injury.
Watering
Most cool-season lawn grasses have the capability to survive extreme drought conditions by going into a summer dormancy. While this is an effective means to survive drought, summer dormancy may result in extensive injury from insects and disease, and encourages weed invasion. Remember, it is a vigorous, healthy lawn that best resistant to pests.
In the early summer, lawns should be watered when signs of wilt appear. Water the lawn thoroughly with about 1-inch of water. This deep watering encourages deeper rooting. As the summer progresses, grasses begin to obtain most of their water from the soil surface. Midsummer waterings should therefore be shallow and more frequent.
The best time to water a lawn is in the early morning. Evaporation losses are low, and the leaves dry off quickly. Evening watering will favor disease development.
Pest Control
Weed Control
The best form of weed control is prevention. Lawns that are damaged or weak are most prone to weed encroachment. Homeowners should follow cultural programs that result in a healthy, vigorous lawn that is tolerant of disease, insects, and environmental stresses. Research has consistently shown that a balanced fertilizer program and proper mowing will help lawn grasses out compete weeds.
Even with the best cultural program, weeds will encroach into a lawn. The only weed control alternative to herbicides is hand pulling. When pulling weeds, be sure to remove all of the root system since many perennial weeds will regenerate new growth from underground parts.
Proper fertilization in the seedbed will help newly seeded areas quickly gain the advantage over weeds. Apply fertilizer according to soil test recommendations. In lieu of a soil test, use a high phosphorus or "starter fertilizer" according to label directions. Once the grass is established, mow as soon as the grass is 3 inches tall. Mowing at this time will control many weeds and also promote thickening of the lawn.
Diseases
The most important lawn diseases in New York include leafspot, patch diseases, (necrotic ring spot, summer patch), red thread, rust, and snowmold. These diseases can usually be controlled through the use of resistant varieties and proper culture. Leafspot is most serious on Kentucky bluegrass lawns when cool wet weather prevails, usually in the spring. If the disease progresses into the early summer, the much more damaging crown rot or "melting-out" stage may develop. Avoid high rates of nitrogen fertilizer in the spring. Raise your mowing height if you notice the disease.
Contact Cornell Cooperative Extension - Suffolk County for cultivars of bluegrass and fine fescues that are resistant to leafspot.
Summer patch is a devastating disease that occurs during hot, dry periods. Perennial ryegrass and several bluegrass varieties are resistant to this disease and should be included in a new seed or overseeding mixture. Summer patch is caused by a root pathogen. Therefore, any practice that encourages deeper rooting will make the lawn more tolerant to this disease, including proper pH and fertilization, proper mowing and irrigation.
Red thread is a disease that is common during cool, wet periods in the spring. The grasses most affected are fine fescues and perennial ryegrass. Select and introduce cultivars that have resistance to red thread.
Red thread is usually favored by low nitrogen and potassium fertility. Therefore, maintaining an ample supply of these two nutrients may should make your lawn more resistant to this disease.
Rust is a disease that is common on Kentucky bluegrass and perennial ryegrass in the fall. It is a disease that is favored by low nitrogen fertility levels. Fall fertilization should prevent rust from ever being a problem.
Snow mold is one of the more serious diseases in upstate New York. The symptoms of snow mold are not usually noticed until after the snow recedes in the spring. Snow mold is a winter disease that is enhanced by succulent growth. Proper fertilization in the fall with nitrogen and potassium should help keep the damage to a minimum.
Timing of application is most important. Avoid fertilizer applications after October 1 and before the last mowing. Fertilizer can be applied after the last mowing, usually in early to mid-November or later on Long Island.
Some natural organic fertilizers and compost will suppress and sometimes prevent disease problems. Compost may contain microorganisms that are natural antagonists to pathogens. Diseases that have been suppressed by these products include red thread, dollarspot and others. Examples of natural organic fertilizers with known disease suppression include Ringer (Judd Ringer Corporation), and Sustane (composted turkey litter).
There are other diseases that may occur on home lawns. Consult with the Cornell Cooperative Extension - Suffolk County to find out what management strategies exist for the disease you wish to control.
Insect Control
There are basically two types of insects that feed on lawn grasses. The surface feeders include chinch bugs and sod webworms. Root-feeding insects include several different white grub species (larva of certain beetles, e.g. Japanese beetle).
As with other pests, a properly maintained lawn will be more tolerant of insects than a neglected or improperly maintained lawn. For example, a lawn that is watered and fertilized may tolerate 10 to 15 grubs per square foot without any visible damage. The same number of grubs, however, may devastate a weak, poorly maintained lawn.
In recent years, plant breeders have been working on varieties of lawn grasses that have insect resistance. They have been able to do so by introducing a fungus called and endophyte into the grass plant that produces a chemical that is toxic to insects. Perennial ryegrass cultivars with insect resistance include All*Star, Repell, Citation II, Dasher II, Pennant, Pinnacle, and Saturn. Fine fescues infected with the endophyte include Jamestown II, and SR 3000. Unfortunately, the toxin does not move to the underground plant parts. Thus, insect resistance is limited to surface feeding insects such as sod webworm and chinch bug.
The most common damaging insect on home lawns in New York is the white grub. There are actually five species of beetles in New York whose larvae feed on turfgrasses. The most common grubs are those of the European chafer and the Japanese beetle. In addition to these we commonly see grubs of the Asiatic garden beetle, Oriental beetle as well as others on Long Island. Currently, there are two biological insecticides labeled for turf.
Milky spore is a naturally occurring bacterial parasite that infects Japanese beetle grubs. It is not effective on other white grub species. Milky spore products on the market do not survive New York winters very well. They have therefore been, at best, marginally effective in New York.
Parasitic nematodes (microscopic worms) are also available for insect control, including grubs. While results with nematodes have been inconsistent, they are a viable choice for insect control on lawns. Homeowners that rely totally on biological controls for white grubs may have to renovate their lawns when heavy grub infestations occur.
Integrated Pest Management (IPM)
Integrated Pest Management (IPM) integrates many factors into a pest management program. IPM is not a pesticide-free program. Proper culture, pest monitoring, sanitation (eg. thatch control), and proper timing and selection of pesticides are all a part of an IPM program. Ultimately, if a pesticide is used, it will be used much more efficiently than in a preventive program.
Turfgrass (home lawn) IPM would incorporate all of the cultural factors discussed in this fact sheet. Following such a program would greatly reduce the reliance on pesticides. However, there may come the time when a weed or insect population reaches and unacceptable or damaging threshold where a pesticide may be justified. Then IPM depends on the proper identification of the pest and the selection of the pesticide that will effectively manage the pest with minimal hazard to the environment. While IPM is not a pesticide-free program, it should reduce the overall pesticide use on home lawns.
Note: Mention of any product by name does not imply endorsement.
Written by: Dr. Norman W.
Hummell,
Turfgrass Science Program Cornell University, Ithaca, New York
For more information contact: Tom Kowalsick, Extension Educator - Horticulture, CCE - Suffolk County
4/03
