Preventing Pest Damage in Home Lawns
Having an attractive, well-kept lawn is important to many home owners. It not only enhances the appearance and value of your property but it provides a relaxing retreat at the end of the day. Recently, concern over the use of chemical pesticides in home lawns and gardens has caused may home owners to look for non-chemical ways to keep their yards looking good. Luckily, it is not necessary to rely on chemical pesticides to maintain an attractive lawn. In fact, preventing lawn problems is usually much easier than trying to treat them after the fact. This brochure outlines some healthy lawn practices to help you head off problems before they start.
- Just a Little off the Top
- Water Only When Needed
- Avoid a Fast Food Diet
- Sweet and Sour Soil
- Manage the Thatch
- Choose the Right Grass
- A Word About Weeds
- All Things Green and Slimy
- A Final Word About Lawn Pests
- For More Information
Just a Little off the Top
Most of the lawn grasses used in Atlantic Canada grow best and are healthiest when kept at a height of 5 - 7.5 cm (2 -3 inches) tall. You may have to adjust your mower to do this, most are set too low. Maintaining the grass at this height enables it to develop a deep root system and creates a dense, thick lawn that is more tolerant of drought and better able to out-compete weeds. Numerous studies have shown that mowing at the correct height can reduce lawn weed problems by 50-80%.
It is important to mow your lawn regularly so that no more than 1/3 of the leaf length is removed at each mowing. Also, you'll get a better cut if the grass is dry and the mower blades are sharp. Dull mower blades shred and tear the grass plants and can result in an unsightly brown lawn. Mower blades should be sharpened annually.
Water Only When Needed
Most lawn grasses need about 2.5 cm (1 inch) of water per week to grow properly. In Atlantic Canada, in all but the driest periods of the summer, lawns usually receive enough water from rain. It's better for your lawn if you do not water it until it really needs it. You can tell that your lawn needs water when footprints stay compressed for more than a few seconds and the grass fades to a dull greyish-green colour.
You can forgo watering and let your lawn go dormant during periods of summer drought. It will rapidly turn green again when the fall rains replenish the soil moisture. However, a lawn that is drought stressed or dormant may be more susceptible to damage from insect feeding (e.g.,chinch bugs) and invasion by drought tolerant weeds.
If you do water during a dry period, it is important to water correctly and put 2.5 cm (1 inch) of water over the entire surface of the lawn. Frequent light watering weakens plants and encourages shallow root growth. Over-watering just wastes large amounts of clean drinking water.
If the soil is very dry, apply the water in stages to allow it to soak in. If the water starts to run off the surface of the lawn, turn off the hose and wait for about an hour before continuing in the same area. During the hot summer months the best time to water is in the morning before 10:00 am. This reduces the amount of water lost to evaporation.
Avoid a Fast Food Diet
All plants need three main nutrients in order to grow. Nitrogen (N) promotes growth and a dark green colour. Phosphorous (P) is essential for root growth and potassium (K) helps the lawn tolerate wear and stress. As grass grows it uses these nutrients from the soil. To maintain a healthy lawn, the nutrients must be replaced through the addition of fertilizer, composts and/or other organic soil amendments. Lawns that are not provided with enough nutrients tend to be slow growing and weak and are often more susceptible to damage.
The key in fertilizing a lawn is to achieve a balance by providing just the right amount of nutrients at the rate the lawn grass can use them. Lawn fertilizer should be applied in April/May or September when the lawn is actively growing. Choose either a bulk organic material (e.g., compost or well rotted manure) a bagged organic or composted fertilizer, or a synthetic "lawn" or "turf type" fertilizer. When using synthetic fertilizers select a product which contains 40- 60% of its nitrogen in a slow release form. Fertilizers containing slow release nitrogen will have one of the following on the label: "slow release N" , "water insoluble N" or the letters "W.I.N". These types of fertilizers release nitrogen at a rate that the plant can use.
Avoid fertilizers that are identified as "fast-acting" , or promise "quick green-up" as they often provide too much nitrogen at once. Too much nitrogen produces soft weak plants which are very susceptible to wear and damage and the excess nitrogen that is not used by plants is flushed out of the soil when it rains. This not only wastes money but can contribute to pollution of surface and ground water.
Leaving the grass clippings on your lawn also helps provide some of the nutrients that it needs. If you follow the mowing and watering guides in this brochure, only a small amount of clippings will be produced at each mowing. These will quickly decomposed back into your lawn and over the season can supply up to 30% of the nutrients the lawn needs.
Sweet & Sour Soil
The pH of a soil is a measure of how acidic (sour) or basic (sweet) it is. The pH is important because it affects the amount of nutrients that are available for the plants to use. If the pH is too low or too high, many plant nutrients that are present in the soil or in the fertilizer may become unavailable to the plants.
Lawn grasses, like many plants, grow best when the soil pH is just slightly acidic and has a pH value in the range of 5.8 to 6.5. The soil in many areas of Atlantic Canada is quite acidic, meaning it has a low pH and often needs lime to raise the pH to the appropriate level. Lawn soil should be tested every three years to determine if lime is needed.
Manage the Thatch
All grasses form a layer of dead leaves and roots, called thatch, between the base of the living leaves and the surface of the soil. Some thatch in lawn is good, it helps cushion the growing point of the grass plant and insulates the soil from high summer temperatures.
However, when this layer becomes too thick it reduces the amount of water and nutrients moving down to the roots of the grass plants. When this occurs, the roots of the grass plants will begin to grow up near the soil surface, weakening the plant. A thick thatch layer can also harbour lawn damaging insects and disease causing fungi. Excessive thatch is usually caused by improper watering and mowing, applying too much fertilizer or heavy use of lawn care pesticides.
To manage thatch, lawns should be top-dressed each year with a thin layer of good quality garden soil or compost. If the thatch in your lawn has built up to more than 1.25 cm (1/2 inch) some of it should be physically removed. You can remove thatch by giving the lawn a hard raking by hand, or by using a special machine. These machines can be rented from equipment rental outlets or you can hire a lawn care company to come in and de-thatch the lawn.
Choose the Right Grass
A good all purpose lawn seed mix is one which contains a high percentage of fescue (often considered a low maintenance grass) along with Kentucky bluegrass and some perennial ryegrass. While a uniform lawn of one type of grass can be very attractive it can also require a high level of maintenance to keep it in good shape. On the other hand, when a lawn is composed of a mixture of grasses it will tend to be more tolerant to a range of growing conditions such as shady areas and dry slopes. As well, different species and varieties of grass vary in their susceptibility to attack from diseases and insects. Using a mixture reduces the chance that an insect or disease will kill large areas of the lawn.
A Word About Weeds
Weeds are by far the most common and most visible pest problem facing home owners. A healthy vigorous lawn is the best defence against weed invasion. Weed problems usually begin in areas where the lawn is in poor condition, the soil is compacted or the grass has been heavily damaged by insects, diseases or other factors. This causes thin or bare patches to appear. Weed seeds that are already in the soil quickly germinate and grow in damaged areas of the lawn.
Prevent thin or bare areas by distributing foot traffic evenly over the surface of the lawn and keep off the lawn when it is very wet to avoid compacting the soil. Thin, bare or damaged areas should be repaired or re-seeded quickly to avoid giving weeds an opening. If areas of the lawn are receiving constant traffic, such as the path to a garden shed or the composter, consider installing a proper path to prevent wear and tear on the grass.
All Things Green and Slimy
Some problems such as algae or moss are a signal that the grass is being grown under poor conditions such as soil that is compacted, low in fertility or in an area that is too shady. The only way to cure these problems and prevent them from coming back is to correct the conditions that are causing the problem.
A Final Word About Lawn Pests
Most of the weeds, insects and diseases that can damage your lawn are always present at low levels. When you maintain a healthy lawn these organisms co-exist with the grass and you usually don't even notice them. But sometimes, even with good lawn care practices, pest problems may develop. If this happens, it is important to correctly identify the pest before trying to control it.
Chemical pesticides can be an effective way to control an occasional pest outbreak, however it is important not to rely on pesticides as a quick-fix solution for all lawn problems. If you do decide to use pesticides, ask your garden centre to help you select products which will have the least impact on human health and the environment. Be sure that they are applied safely by following all of the label directions.
Remember, re-occurring pest problems in your lawn are often a sign that the growing conditions are not suitable for grass. Although it may take a few years, following the healthy lawn practices outlined in this brochure will help you create an attractive healthy lawn that can resist pests naturally.
