Symptoms

Yellow patches that are 10 cm or more in diameter.

Period when symptoms appear 

Mid-July to late July.

Organism responsible

The bluegrass billbug is a grey-black insect, 7 to 8 mm long. Its larvae are white, legless and have a brown head.

Detection

Grass does not regain its green colour after watering and the blades break when pulled.

Preventive measures

• Increase the mowing length (6-8 cm)
• Aerate
• Seed the damaged patches.

Control methods
There is no insecticide available and approved under Quebec law for dealing with the bluegrass billbug. The only way to control this pest is to use the appropriate lawn care methods.

Symptoms

Appearance of circles that are 10 to 20 cm in diameter that are dark green at first then turn yellow. Dog urine causes grass to turn yellow because it is very rich in ammonia.

Period when symptoms appear

Any time during the growing season.

Detection

Some patches of grass remain yellow in the spring while the rest of the lawn has already turned green.

Preventive measures

• Keep dogs off your lawn or restrict their access to a given area (perhaps covered in rock dust) where they can relieve themselves.
• Water the grass in order to mask the most severely damaged areas, then reseed.

Symptoms

Yellow patches 7 to 13 cm in diameter.

Period when symptoms appear

Early summer and then again in the late summer/early fall.

Organism responsible

Disease called “dollar spots”.

Preventive measures:

• Increase the mowing length (6-8 cm)
• Aerate
• Water generously in the early morning (between 5:00 a.m. and 8:00 a.m.).

Symptoms

Irregular yellow patches ranging in size from a few centimetres to several metres in diameter.

Period when symptoms appear

Early spring.

Detection

Some patches of grass remain yellow in the spring while the rest of the lawn has already turned green.

Preventive measures

• Leave the grass longer when you mow to promote deeper root development.
• Water for longer periods but less frequently to foster deeper root development.
• Reseed damaged areas.

Symptoms

Yellow patches that are 10 cm or more in diameter.

Period when symptoms appear

Mid-July to late July.

Organism responsible

The hairy chinch bug is a small insect (< 3mm) that feeds on sap from the grass.

Detection

Presence of a dozen or so of hairy chinch bugs (reddish-orange) on a blade of grass. The patches of yellow grass get bigger even after watering.

Preventive measures

• Increase the mowing length (6-8 cm)
• Aerate
• Seed the damaged patches.

Control methods

When the chinch bugs are present during the month of July, apply insecticide soap in the morning or evening. Repeat this treatment one week later.

In case of a major infestation, contact your local Vertdure branch.

Symptoms

Grass turns yellow over nearly its entire surface.

Period when symptoms appear

During heat waves and in droughts (most commonly in July)

Detection

Grass turns yellow and doesn't straighten after being walked on.     Note that Kentucky bluegrass goes dormant when under stress. This allows it to survive these types of conditions. It is not in danger, because it will return to its normal appearance after the rain returns.

Preventive measures:

• Increase the mowing height or do not mow it at all during these periods.
• Water for longer periods but less frequently to foster deeper root development.

Symptoms

Irregular yellow patches ranging in size from a few centimetres to several meters in diameter.

Period when symptoms appear

September or October.

Organism responsible

The webworm is a small white butterfly that zigzags over the lawn when disturbed. The butterflies themselves do not damage the lawn and are present from late June until late August. The beige larvae are about 2 cm long and are responsible for damaging the lawn.

Detection

Grass can be pulled out easily. Presence of beige larvae on the ground.

Preventive measures

• Aerate
• Seed the damaged patches.

Control methods

Some insecticides can be used to control webworms. Contact your local Vertdure branch for more information.

Symptoms

Irregular patches of yellow grass that can reach up to a meter in diameter and sometimes even more. Lawn torn up by skunks that like to feed on the grubs.

Period when symptoms appear

April-May and late August to early September.

Organism responsible

White grubs are the larvae of the June beetle.

Detection

The grass is no longer fastened to the soil and can be pulled out easily. Presence of white, "C"-shaped larvae (1 to 5 cm long).

Preventive measures

• Increase the mowing length (6-8 cm)
• Seed the damaged patches.

Control methods

Apply nematodes (microscopic worms that attack white grubs) in mid-August when the soil temperature is adequate. After applying the nematodes, water generously to allow them to penetrate the soil.

An insecticide that is very effective against white grubs is available. Contact your local Vertdure branch.