Winter Pests and Lawn Diseases

Grass with winter lawn disease

When the cold weather of winter hits, lawns generally tend to go into hibernation. That means the grass grows less, turns brown, and reserves its energy for spring. You’d think that would mean common lawn pests and diseases would go into hibernation as well. Not so much. In fact, homeowners need to keep an eye out for winter bugs and winter lawn diseases that thrive when temperatures drop.

By being ready for common winter pests and diseases, you can better protect your lawn from them. Here’s a rundown of the suspects for winter lawn damage.

Common Winter Bugs

Bugs are most likely to make themselves known in the summer months, but many pests survive and even thrive when the weather outside is frightful. Even during the darkest, coldest days of winter, you can’t relax your pest control measures. Here are some winter pests to look out for.

White Grubs

White grubs in soil

When you look out at your winter lawn, you might not see anything amiss. However, deep down in the soil, these C-shaped beetle larvae could be thriving. White grub larvae feed on the dense roots of a lawn, which can cause patches of your lawn to die in the late winter or early spring. White grubs are the juvenile form of several different bugs, including Japanese beetles, chafers, and June bugs. What’s worse is that many other lawn pests, like moles, skunks, and crows, feed on white grubs and don’t mind digging up lawns to get at them.


Billbug on a green leaf

Like white grubs, billbugs do most of their damage in the winter in their larval stage. Rather than living in the soil, however, these cream-coloured, legless larvae feed on the stems and crowns of grass. This activity leaves signature holes in grass blades and stems. When billbug larvae drill through grass plants, they disrupt the plant’s ability to absorb water and nutrients. When enough billbug larvae are in a lawn, they can create patches of yellow or dead grass in late spring or early winter. Adult billbugs will begin to emerge in early spring.


Mealybugs on blades of grass

Mealybugs are tiny, soft-bodied insects that primarily thrive in cooler months. An infestation can grow quickly and cause significant damage to a lawn. Mealybugs feed on plant sap. They can live in a lawn’s root system, on the lower stems of grass, or on grass crowns. When they feed on grass, they weaken the plant’s ability to absorb nutrients. This can be extra harmful when grass is in its more vulnerable dormant stage.

Mealybug populations expand rapidly, which means they can do a lot of damage quickly. While it’s hard to see mealybugs with the naked eye, you may notice that your grass turns yellow or thins out in early spring. Mealybugs also attract ants, so if you notice a lot of ants in your lawn in the spring, that may be an indication of a mealybug infestation. These ants can march right into your house. So if you don’t want bugs in your house in winter, take care of mealybugs before they become a problem.

Common Winter Lawn Diseases

It’s bad enough that you have to worry about creepy crawlies munching on your lawn during winter, but you also need to keep an eye out for winter lawn diseases. Here are a few diseases that tend to thrive when the weather gets cold.

Snow Mould

Lawn with snow mould

This fungal disease thrives in wet conditions, including under snow cover or frost. The two most common types of snow mould are gray snow mould and pink snow mould. While neither option is desirable, gray snow mould tends to be more damaging than its pink counterpart. If you have snow mould, you’ll start to notice matted, circular patches of lawn that can grow as big as a meter wide. The centre of these patches may turn a grey or reddish-pink hue. In more severe cases, snow mould can kill off large sections of your lawn.

Powdery Mildew

Grass with signs of powdery mildew

If you notice your grass covered in a white or gray powdery substance, you may have a case of powdery mildew on your hands. This fungal growth thrives in cool, humid weather, especially in areas with poor air circulation and lots of moisture. The wind spreads powdery mildew spores, meaning it can quickly take over a lawn. Powdery mildew coats grass, weakening your lawn and making it vulnerable to other diseases. As an infection takes hold, grass can turn yellow and struggle to grow. You may also notice that your grass seems stunted.

Lawn Rust

Blades of grass with lawn rust

Yet another fungal winter lawn disease you need to look out for is lawn rust. This disease manifests as a noticeable reddish or orange powder that covers grass blades. It can actually look a little like your lawn is rusting. Lawn rust is most common during cooler months, specifically in late fall, winter, and early spring. While many cases of lawn rust are mild, it can still weaken your lawn, making it susceptible to other diseases. In severe cases, lawn rust can lead to dieback.

Leaf Spot Diseases

Lawn showing signs of leaf spot diesase

This group of diseases is caused by fungal pathogens and often manifests as visible patches or circular spots of dead grass. Leaf spot thrives in areas that provide lots of humidity, shade, moisture, and poor air circulation. It most often spreads in winter and early spring. While there are several variants of leaf spot disease, one of the most common is necrotic ring spot, which causes dark circles and dead spots of grass that can be over a quarter of a metre wide.

How to Get Rid of Winter Bugs and Winter Lawn Diseases

Rake in leaves

Though winter pests and winter lawn diseases vary in causes and characteristics, the way to manage them is roughly the same. Prevention is always the best medicine, and taking good care of your lawn can go a long way toward protecting it from infestations of every kind.

For example, mowing your lawn regularly, dethatching, raking leaves, and pruning back shrubs can all limit areas where pests tend to thrive.

Aerating, fertilizing, and watering your lawn throughout the year will keep your grass healthy and strong, which can help it resist common fungal infections.

Of course, if you have an active pest infestation or disease infection, you’ll want to take action. That may mean using a safe insecticide or fungicide on your lawn.

Lean on The Grounds Guys

Don’t have the time or energy to perform regular lawn maintenance? The Grounds Guys® can help. We have local teams throughout Canada who can perform ongoing lawn maintenance as well as seasonal services that will keep your lawn strong and healthy. Our teams are friendly, reliable, and knowledgeable. That’s part of our Neighbourly Done Right Promise™ to all our customers.

Interested in a free estimate? Just find your local The Grounds Guys team and request a job estimate! We’ll keep your lawn healthy throughout every season.