How to Treat Rust Diseases in the Lawn

Have the grass blades on your lawn begun to look like they've been coated with rust? Here's what's going on— and what to do about it.

Have you noticed your grass blades looking like they’ve been dusted with an orange-yellow powder? Unlike the rust on a car, which is from a chemical reaction, lawn rust is caused by a common fungus. It gets its name from the rusty appearance it gives the grass.

While it may look alarming, rust is a treatable issue. Use these expert tips to figure out if rust is the problem in your lawn and how to get it under control.

How to Identify Rust Disease

If you think you have a rust problem, here are the key signs to look for:

Irregular Yellow Patches: The first signs are often irregular, light-yellow patches in the lawn.
Orange Powder on Blades: As the disease progresses, small yellow flecks on grass blades rupture and release yellow-orange, powdery spores. This powder will stick to anything it touches, from your shoes to your lawn mower.
Thinning Turf: In severe outbreaks, you might notice the turf thinning out and grass blades dying back.
Good News for Pet Owners: Don’t worry, grass rust is harmless to pets.

What Causes Lawn Rust?

Rust diseases are most likely to appear from spring through fall during mild, wet weather. However, rust can also develop during dry, sunny periods that follow humid weather.

Stressed and underfed lawns are especially susceptible to rust. The disease is often worse in areas with compacted soil, shade, or where there is not enough nitrogen for healthy growth.

Grass Types Most Affected by Rust

Rust can affect both cool- and warm-season grasses, but the grass types that are most susceptible are:

Perennial ryegrass
Kentucky bluegrass (some varieties)
Zoysiagrass

The grass types with the best resistance to rust are:

Tall fescue
Bermudagrass
St. Augustinegrass
Centipedegrass

Your Best Defense: How to Prevent Rust

Because stressed lawns are more likely to get rust diseases, one of the best ways to prevent them is to keep your lawn healthy and strong.

Feed Properly. A well-fed lawn has the nutrients it needs to grow deep, strong roots that can better withstand diseases. Take the guesswork out of feeding with a personalized Scotts® Lawn Care Plan.
Water Correctly. Water your lawn deeply, but infrequently. The key is to provide adequate moisture—not too little and not too much. Water in the morning so grass blades can dry during the day, which helps prevent fungal growth.
Aerate and Dethatch. Aerating and dethatching every 1 to 3 years helps air, water, and nutrients move more freely into the soil.
Mow Regularly. Mowing your lawn to the proper height for its grass type encourages strong, vigorous growth.

How to Treat Lawn Rust When It Appears

If you’ve identified rust in your lawn, start by making sure your lawn is well-fed and correctly watered. Along with good lawn care practices, a fungicide can help control the current outbreak and prevent new ones.

For Targeted Control: Apply a systemic fungicide like Scotts® DiseaseEX™ Lawn Fungicide. It starts working within 24 hours to control rust and other listed diseases, and continues to work for up to 4 weeks.
To Feed and Prevent: A healthy, well-fed lawn is less susceptible to rust. To feed your lawn and get ahead of diseases at the same time, use a Scotts® spreader to apply Scotts® Turf Builder® Healthy Plus Lawn Food. It controls up to 27 listed lawn diseases while providing nutrients for a thicker, greener lawn.

When applying any fungicide product, always be sure to follow the directions on the label.

How to Repair Your Lawn After Rust

Once the rust is under control, you may be left with bare or thin spots.

For Bare Spots: Use EZ Seed® to patch any bare areas. It contains high-performance seed, water-absorbent mulch, and slow-release fertilizer to help new seedlings thrive.
For Thin Areas: For larger areas of thinning grass, use a Turf Builder® Thick'R Lawn® product to seed, feed, and improve your soil all in one application.

Rust isn't something you want in your grass, but the problem is both treatable and preventable. Follow these tips, and you’ll be on your way to a healthier, more beautiful lawn.