|Turf care insects and diseasesBenefits of a Healthy Lawn
As homeowners, we are all interested in keeping our lawns looking their best, free of unsightly weeds and destructive lawn pests. But maintaining a healthy lawn is also important to the environment.
- A 50-ft by 50-ft healthy lawn provides enough daily oxygen to meet the needs of a family of four.
- Grass cools naturally. Eight average-size lawns have the cooling effect of 70 tons of air conditioning (the average home central air conditioner produces about 3 tons).
- A well-managed lawn and landscape can boost the value of a home by as much as 15 per cent.
- Grasses reduce undesirable noise levels by 20 to 30 per cent.
- Healthy lawns absorb rainfall four to six times more effectively than farm fields. They return the moisture to the water table, where it can be used by everyone.
- Weed-free lawns remove pollutants from the air, prevent water and wind erosion and the loss of precious topsoil, reduce allergens and the likelihood of insect bites and stings, absorb and reduce glare and act as a cushioned surface for outdoor activities and sports.
A healthy lawn is more than a just a thing of beauty, it is a vital living part of our environment that, with proper care, can improve the quality of life we enjoy and the cleanliness of our world.
Programs for a Greener Lawn
Feeding – Fertilizers provide nutrients necessary for plant health and growth, such as nitrogen, phosphorus and potassium. Nitrogen is needed for healthy green growth and regulation of other nutrients. Phosphorus helps proper roots and seeds develop and resist disease. Potassium is also important in root development and disease resistance. For the healthiest lawn, it is recommended that fertilizing be done up to 3times a year, a healthy lawn will deter weeds .and survive pest attacks
Mowing – The idea height to keep a lawn is at a level of 2.5 to 3 inches. No more than one-third of the height should be taken off during each cutting. When the grass is overgrown, bagging may be necessary to avoid an accumulation of clippings; however, mulching is preferred as it allows the grass clippings to be recycled, providing extra nutrients for the lawn. Avoid cutting grass with dull mower blades. When the blades are dull, they shred the grass rather than cutting it. The shredded ends will then dry out giving the lawn a brownish twinge. Cutting the grass too short especially along walks and driveways allows light and heat to reach the soil aiding the germination of weed and crabgrass seeds.
Watering – Watering is recommended as soon as the first signs of drought appear. A healthy lawn should receive an average of 1 inch per week It is best to water early in the day, before the sun is too intense to avoid evaporation. Avoid watering in the evening; leaving the grass wet overnight and providing a perfect breeding ground for fungi. Encourage roots to grow deeper by doing a thorough watering (3-4 hours), once a week, rather than short waterings more often. A rain gauge is an ideal way to check and ensure that the grass is receiving the proper amount of water before drought stress appears
If access to water is unfeasible or restricted the grass will go into dormancy, and turn brown, this is a normal protective device. If you cannot water consistently to keep the grass alive do not give the lawn a smaller amount of water to revive it periodically during a drought as this weakens the grass , after 4 weeks of dormancy grass plants will start to die at this time a good soaking is necessary to revive the lawn. Hot dry periods allow chinch bugs to thrive and cause damage. It also thins the grass allowing crabgrass to germinate
Aerating – Aerating, which should be done when the soil is moist has enormous benefits, Aerating alleviates hard, compact soils (usually clay soils). Helping water, air and fertilizer to get to the grass roots, promoting health and insect and disease resistance It helps to break up some excess thatch. And promotes germination of grass seeds when combined with over seeding.
Dethatching – Up to 1/2″ of thatch is desirable to reduce soil drying, but any more than that can provide a perfect environment for insects and fungi to infest
These are just a sample of the many insects that can damage your precious lawn, causing brown patches and eventually destroying your entire lawn. (i.e. Chinch bugs can wipe out an entire lawn in only six weeks)
European Chafer & June Beetle
Grubs are the larval stage of a beetle. The June beetle and the European Chafer (similar to June beetle, but slightly smaller) are the two beetles that do damage to lawns in this area. Grubs feed on the roots of many plants but prefer the fibrous roots of turf grasses. As the root system gets destroyed, sections of the turf begin to wilt and turn brown. The grass can often be picked right off the soil because there is little or no root system to hold it in place. Skunks will often do additional damage by digging up the lawn searching for grubs to feed on. Since the ban on grub killers nematodes which feed on the grubs have been used as a deterrent with mixed results. Because of the exacting conditions of weather as nematode are killed by direct sunlight and dryness, each treatment will only destroy approximately 20 to 50% of the grub population. A new control, Met 52, just approved will reduce the grub population by infecting the grubs at all stages. Met 52 is applied in mid summer and unlike nematodes is not dependent upon water and ideal weather conditions to work.
A healthy lawn can generally handle up to 3-5 grubs per square foot. At these populations the grass can regrow its roots as fast as the grubs can eat them
Crane fly – Leather jacket
The Crane Fly is the adult stage of this insect, measures about 1 inch long and is brownish in colour. It also looks like a large mosquito but will not bite you. The Leather jacket is the larva stage of this Crane fly, also measures about 1 inch long and is grey to greenish brown in colour. These insects actively feed on turf grasses in the spring and fall and this is the best time to control them. The adult does not damage the grass but will fly around breeding and depositing eggs in the grass. One Crane fly can lay several hundred oval block eggs in the moist turf soil. When the eggs hatch the larvae can cause severe damage to all types of grasses, feeding on the roots and grass leaves. Treatment is similar to grub control.
Chinch bugs have traditionally been the problem insect in home lawns. The adults overwinter under debris in flower beds, shrubs and trees. In the spring the females move into the lawn and begin laying their eggs. The first eggs hatch into nymphs in late May – early June. There are 6 stages (instars) before they become adults. The chinch bugs have piercing mouthparts that suck the sap from the crown and stems of the turf grass. Damage appears in late July – early August ;as hot dry weather favours their development; showing up as localized dead patches that expand The chinch bug live in the thatch of the lawn. In September the adults begin migrating out of their feeding areas and begin looking for overwintering sites. The adults have either full wing development, which means they can migrate a few blocks away or partial wing development which means they migrate to your flower beds and shrubs. The best control is achieved by healthy lawn care practices.
The sod webworm is the larval stage of the adult lawn moth. The damage can be extensive but is generally isolated to a few lawns in a neighborhood. The adult, which has a long snout, will fly out of the lawn in a zigzag pattern when disturbed.
The adults randomly drop eggs onto the grass and these hatch into the larval stage. There are 2 to 3 generations per year and each generation will produce more adults. The population becomes cumulative and therefore the worst damage is generally in the fall. The sod webworm builds a silk burrow in the thatch and comes out at night to feed. It chews off grass leaves and drags them into their burrows where it will feed on the grass.
Turfgrass Scale is an insect that is native to Europe but has recently been introduced into Ontario. Because it is so recent in some areas, it is difficult to determine just how extensive the damage will become. It has one generation per year and has 3 instars. The third instar female nymph overwinters in the soil along the roots as a salmon pink bundle. In the spring they move out of the soil onto the grass. They have piercing mouthparts that suck the sap from the crown and stems of the turfgrass. This is the damaging phase. The adults lay up to 400 eggs usually in June which hatch into small red crawlers in July. Thousands of these crawlers can cover large areas of the lawn and get onto shoes, play equipment and picnic tables. Although they are a nuisance, this is not a damaging instar stage.
The black cutworm is the larval stage of a large moth that flies in from the United States each spring. It lays its eggs in the spring and the eggs hatch into a cutworm that has black dots on each body segment and a strip along its length. The black cutworm comes out from its soil burrow at night to feed on the grass leaves. It may also cut off grass plants without feeding on them adding to their destructive nature. It is usually isolated to small areas within the lawn but these small areas can be extensively damaged.
Cleanliness and good lawn care programs to reduce the conditions favourable to lawn disease, are the best ways to decrease lawn disease problems.
Pink Snow Mold (Typhula Spp.)
Grey Snow Mold (Microdochium nivale)
A disease that develops under snow cover during the winter months. It is first evident in the spring after the snow cover melts. It affects all northern grasses especially perennial rye grass. The conditions favoring the disease are lush growth in the previous fall, extended periods of snow cover, soil temperatures of -1 to -4 degrees Celsius below the snow cover, and high moisture content. It will appear as small greyish-white or pinkish patches up to 25 cm in diameter.
A disease that can occur in the spring and fall when there is plenty of moisture and the grass is actively growing. It affects all northern grasses especially perennial rye grass and fine fescue. The conditions favoring the disease are grasses low in nitrogen content, air temperatures between 15 to 25 degrees Celsius and high moisture content. It will appear as diffuse, irregular patches from 5-35 cm with pinkish red strands developing on individual leaves.
Necrotic Ring Spot
It is the most serious home lawn disease because it targets Kentucky bluegrass (the most common grass) and fine fescues. The fungus affects the roots 12 to 18 months before symptoms appear in the grass itself. Dead rings from 10 cm to 1 m develop that have green centers. The disease is associated with sod and compacted soils.
A disease that develops in shaded areas of lawns often between houses, under trees and on the north side of properties. It affects all northern grasses especially Kentucky bluegrass. Conditions favoring the disease are humid or wet shaded areas, with poor air circulation and temperatures between 15 and 20 degrees Celsius. It appears as dull white powdery growth on the leaves.
Helminthosporium Leaf Spot
A disease that develops in the cool, moist conditions of spring and fall. It affects all northern grasses especially Kentucky bluegrass. Conditions favoring the disease are excess fertility, mowing height of less than 1 inch, leaf wetness for greater than 10 hours and temperatures between 3 and 27 degrees Celsius. It appears as elliptical lesions on the leaf blade. The lesions have dark borders and bleached centers often with a yellowish halo around the lesion.
A disease that generally shows up late August or early September. It affects all northern grasses especially Kentucky bluegrass and perennial rye grass. It is unusual in that it requires an alternate host to develop. Conditions favoring the disease are low light and 22-25 degree temperatures for infection and high light and 26-35 degree temperatures for disease growth. It appears as small, numerous yellow-orange powdery growths on the leaves.
There are 3 common varieties of this disease. These are a mushroom ring, a killing ring, and a stimulated ring, with the last being the most common in Ontario. The stimulated ring appears as a circle or crescent of darker green and more rapidly growing turf grass. Grass in the inner part of the circle grows more slowly because of the presence of a mass of white mycelium. These circles range from a few centimeters to a few meters in diameter.
A disease that can affect all northern grasses but is more common on golf greens than in home lawns. Conditions favoring the disease are grasses low in nitrogen content, excess thatch , extended leaf wetness and temperatures in the 21-27 degree Celsius range. It appears as hourglass lesions on the leaf blade with a bleached area crossing the entire leaf blade surrounded by a brown margin. The mycelium can look like cobwebs on the grass in the early morning.