Are White Grubs Destroying Your Lawn?
White grubs are the larvae of three species of beetles and are one of the most difficult lawn pests to deal with. If left untreated they can easily destroy a lawn. The most common white grubs in Ontario are the June beetle or June bug, the European chafer and the Japanese beetle. Grubs in a lawn feed on the roots of many plants, but prefer the fibrous roots of grass. Grub damage is most severe in the spring and fall when moisture levels in the soil are high. This moisture allows the grub to move easily in the soil. White grubs can be found near the surface in the late spring and early fall when they are actively feeding.
How Do I Know I Have Grubs?
- Skunks and raccoons will pull back the turf to feed on grubs in the spring or fall. Flocks of birds such as starlings and blackbirds feeding on the lawn are also signs of a grub infestation. Many people notice animals digging as the first indicator.
- As the roots are eaten the turf will begin to wilt and turn brown.
- Affected areas will feel soft and spongy to walk on.
- Turf in affected areas can be pulled back and up with ease, like a carpet. Once you pull back the turf the grubs will be visible.
If you notice any of these issues in your lawn immediately check for white grubs.
How Can I Prevent Grubs?
Cultural practices are the best way to ensure the health of your lawn before any problems arise. A strong and healthy lawn can tolerate more grub feeding than a stressed lawn because damage to one root is compensated for by others. Healthy lawns will also have strong leaf tissue that will provide important nutrients and energy to repair the root damage. Deep and infrequent watering will encourage deep rooted and drought tolerant lawns. Make sure that you are fertilizing your lawn on a regular basis. Topdressing and seeding your lawn in the spring and fall is also highly recommended. When choosing a seed make sure to use grasses containing an endophytic fungus such as fescues and ryegrasses. This type of fungus naturally repels white grubs.
How Can I Treat Grubs?
The most commonly used grub control product in Ontario is the nematode, Steinernema carpocapsae. This micro organism is a parasite for white grubs. Nematodes require that the soil be kept very moist to support the nematode’s growth as well as to allow them to move freely within the soil. It is very important that the application instructions for this product be followed closely, as nematodes are living organisms that can be killed through improper handling, resulting in decreased effectiveness.
When a lawn has been damaged by grubs it will need to be repaired. If the lawn has simply been pulled back by digging animals it should be placed back on the soil, pushed down and heavily watered. However more serious lawn renovations that include topdressing and seeding are often required. Topsoil should be applied and raked in at no more then 3/8 of an inch in depth. More then this may damage existing grass by smothering it. When choosing a seed make sure to use grasses containing an endophytic fungus such as fescues and ryegrasses. This type of fungus naturally repels white grubs.
Topdressing and seeding should be done in the spring and the fall when temperatures are moderate and precipitation is common. In the event that natural precipitation is not occurring then daily irrigation to a depth of 2 to 3 inches is required to ensure good germination of the grass seed. Do not cut the new grass until it has reached a height of 3 inches. Frost will damage or kill newly germinated grass. As a result make sure that any seeding is done outside of a frost window.
Dr. Green is pleased to offer this service to all of our clients that are on a lawn care program at a 20% discount off of our already low prices.
