How to Identify Lawn Diseases

Something looking not quite right on your lawn, but you're not sure what it is?

Welcome To The Lawn: How to Control Lawn Pests

Anytime you grow a bunch of the same plants together, disease problems can take hold and begin to spread before you even notice they’re happening. This can be a real challenge for lawns, because lawns are made of hundreds of thousands of the same type of grass plants. Even when you give your lawn excellent care, the grass can still become infected with various lawn diseases that can lead to dead or discolored areas. Disease spores can float by in the air or hide in the soil, and when conditions are right, they multiply. That’s why it’s a good idea to protect your lawn, or fight back if disease has already taken hold, withScotts® DiseaseEX™ Lawn Fungicide. It starts to work in just 24 hours to prevent and control 26 different lawn diseases for up to 4 weeks (when applied as directed).

Here are some of the most common lawn diseases and how to identify them.

Brown Patch

Grasses typically affected: tall fescue, perennial ryegrass, bentgrasses, Kentucky bluegrass, St. Augustinegrass

Brown patch most commonly affects lawns during hot, humid summer weather. It usually shows up as large, roughly circular, somewhat irregular patches that appear to be either dry or dead. The outside of the patch may sometimes appear to be darker than the inside. If the disease has been active for a long time, the inside of the patch may recover, leaving a ring of dead or thin grass around it. With St. Augustinegrass, brown patch can look like a brownish interior patch with a yellow outer ring.

Red Thread

Grasses typically affected: bermudagrass, bluegrasses, fescues, bentgrasses, perennial ryegrass

Red thread thrives in cool, humid conditions like those common in the Pacific Northwest, and shows up most frequently in lawns grown in nutrient-poor soils. You’ll know you have it if you see thin, red hairs or strands extending from the grass blades. Red thread can survive for years if left untreated.

Rust Diseases

Grasses typically affected: zoysia, perennial ryegrass, Kentucky bluegrass

Rust diseases appear as irregular light-green or yellow patches on the lawn, but if you look closely, you’ll see orange-yellow rust spores on the individual grass blades. You’re most likely to see this disease in the late summer and early fall, especially in shady areas with poor ventilation. Sometimes rust will appear in the spring if the lawn has not been fertilized properly, so be sure to feed your lawn throughout the year to help prevent it.

Snow Mold

Grasses typically affected: ryegrasses, creeping bentgrass

There are two types of snow mold: pink snow mold and gray snow mold. While snow mold generally grows under snow cover, pink snow mold can also grow during cool, wet weather when there’s no snow on the grass. It appears as grayish-white or whitish-pink patches of crusty, matted grass, and is most noticeable in early spring when the snow begins to disappear. Learn more about snow mold right here.

Summer Patch

Grasses typically affected: Kentucky bluegrass, fescues, annual bluegrass, bentgrass

Summer patch usually appears between June and September, during periods of high humidity when daytime temperatures are over 85 degrees. It will show up in the form of irregular brown patches, rings, and crescent shapes. While the disease may still be present during cooler weather, the symptoms won't be as apparent.

If you identify one of these diseases on your lawn, don’t panic. Simply apply Scotts® DiseaseEX™ Lawn Fungicide according to label directions and you’ll soon have the problem under control.

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