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What Is Grass Rust and How to Remove It (2021)

Your lawn isn’t actually rusting, but it may have a fungal disease that weakens the grass blades and sheds orange powder. Fortunately, although this infection weakens turfgrass, it rarely kills it. We’ll show you how to get rid of it.

A close-up of a green grass lawn with grass brown rust spots Adobe

If you take a walk through your yard and come out with your shoes covered in a substance that looks like orange or brown dust, your lawn may have come down with a case of grass rust. This condition is caused by a fungus and although it can look serious, it is relatively easy to treat. We’ll explain what grass rust is and how to remove it, and then we’ll recommend our picks for the best professional lawn care services to keep your grass looking green and healthy.

What Is Grass Rust and What Causes It?

Grass rust is not a single lawn disease but rather a name for several species of a fungus called Puccinia or Uromyces. The yellowish-orange dots that you see on grass blades are actually the spores of this fungus, which is how it reproduces.

The fungus spreads when animals or humans pick up the spores on the skin, fur, or clothing and move them to an uninfected location. Although spores need to be present for the infection to start, certain weather conditions make this fungal disease much more likely.

Lawn rust is most likely to develop in the summer or early fall when temperatures are warm and humidity is high. According to the University of Illinois Extension Agriculture Program, here are some specific conditions that contribute to the growth of rust fungus:

  • A season of excessive, heavy rain that depletes soil nitrogen
  • Cool nights with heavy dew and frequent rainfall
  • Cloudy, humid weather followed by hot, sunny weather
  • Low soil nitrogen and low water availability that leads to slow growth

Signs and Symptoms of Grass Rust

The symptom of rust diseases that you’re most likely to spot is the obvious one: small, yellow dots on grass blades that develop into orange or brown pustules. When touched, these pustules rupture easily and spread a powdery substance that’s a rusty orange in color. The individual grass blades themselves will begin to look thin and weak, and they’ll break more easily.

Bermuda grass, Kentucky bluegrass, perennial ryegrass, and tall fescue are all susceptible to developing grass rust. Although this lawn fungus typically won’t kill the infected turfgrass, it will weaken the grass, leaving it less able to photosynthesize and withstand damage or other lawn diseases.

How to Prevent Grass Rust

The best way to prevent lawn rust is to invest in the general health of your lawn. A robust, healthy lawn is better able to fend off all types of grass disease, and regular lawn care is a big part of the equation.

Know what species of turfgrass you have and how it responds to changing seasons throughout the year. Mow regularly, keeping stress on the grass to a minimum by setting your lawn mower to cut off no more than one-third of the length of the blades at a time.

Proper fertilizing is also a key part of the process. Insufficient soil nitrogen can weaken turfgrass, leaving it susceptible to disease. However, huge influxes of nitrogen can cause quick overgrowth, which then depletes the grass’ resources and also leaves it weaker. Steady, seasonal fertilizing customized to your soil and turfgrass’ needs gives it the best chance to fight off grass rust.

Determine whether your lawn contains cool-season grass like tall or fine fescue or Kentucky bluegrass, or a warm-season species like Bermuda grass or zoysia grass. Cool-season grasses go dormant in the heat of summer and hit their growing season when temperatures begin to cool off in the fall. Warm-season grasses, on the other hand, grow fastest in the spring and early summer but go dormant in the winter.

Fertilize each type of grass as it begins its growing season—that means the early fall for cool-season grasses and the spring for warm-season grasses.

How to Treat Grass Rust

Fortunately, you typically don’t need fungicides to treat rust-infested grass. Usually, some intensive lawn maintenance will get rid of rust in your lawn.

First, you typically want to reduce moisture levels that are allowing the fungus to flourish, so hold off on watering your lawn until the grass needs it instead of relying on automatic sprinklers. In general, deep but infrequent watering is better for your lawn than frequent, shallow irrigation. Additionally, water in the morning to let the lawn dry out during the day.

Next, fertilize the lawn with a high-nitrogen fertilizer, preferably a slow-release formula that will keep nitrogen levels steady over a longer period. Don’t go overboard in the late fall, though, since warm-season grasses are about to go dormant for the winter and cool-season grasses suspend their growth. If it’s later than September or October, you may want to wait out the winter. Chances are that the fungus will die out in the cold.

Keep mowing regularly, but make sure to bag grass clippings instead of letting them scatter, which can actually further spread the rust.

Lawn aeration can help, as well, since it reduces soil impaction and improves drainage. If your grass is a species that produces thatch, performing a gentle dethatching will help improve air circulation around the grass, preventing it from holding on to too much moisture.

Finally, prune back trees and shrubs as much as possible to allow your grass increased sunlight and air circulation.

When to Call in the Pros

Although fungicide isn’t usually necessary, the types of fungicide that are effective against lawn rust typically aren’t available to consumers. You’ll need to call a professional and have them apply the substance to your lawn.

However, this should only be used as a last resort, because some fungicides can damage grass. If you consult a professional about lawn rust, they’ll help you create a fertilizing and maintenance plan that will help strengthen your grass to fight off the fungus naturally.

Our Top Picks for Professional Lawn Care

Luckily, there are plenty of good options for professional lawn care providers. Our first choice is TruGreen, a nationwide company that specializes in customizing fertilizer, aeration, and weed control to your lawn’s needs. Every treatment plan begins with an analysis of the soil, and every plan comes with a Healthy Lawn Guarantee. TruGreen’s technicians can even provide lime treatments and some tree and shrub care. For a free estimate, call 1-866-817-2287 or fill out this quick form.

Alternatively, if you prefer a more hands-on approach to lawn care, Sunday is a new subscription service that uses satellite imaging and climate data to customize a plan for your lawn. The company will mail you the necessary treatments, which you can then apply yourself with equipment no more specialized than a garden hose. You can save some money by doing the work yourself but also receive the benefit of professional expertise. For more information, visit Sunday’s website.

Frequently Asked Questions

Is grass rust harmful to people or pets?

No, the fungus that causes grass rust won’t harm you, your kids, or your pets. However, a child or dog who plays in a yard full of grass rust will probably need a good rinse-off before coming inside. The brightly colored rust spores could stain carpets.

Will lawn rust go away on its own?

Depending on the severity of the infection, it might, but you’ll probably have to wait through the winter for it to happen. A quicker solution is putting down a bit of fertilizer and reducing excess soil moisture.

Will rust fungus kill my grass?

The fungus that causes lawn rust needs a living host to survive, so no, lawn rust alone typically won’t kill your grass. The problem is largely one of appearance. However, it will weaken the grass, making it more susceptible to drought, damage, and other diseases.

What’s the difference between red thread and lawn rust?

Both grass rust and red thread are lawn diseases caused by a fungus, and they both tend to affect the same kinds of turfgrasses.

However, grass rust produces a yellow, orange, or brown powder that will come off on your shoes as you walk through your lawn. Red thread, on the other hand, will cause isolated patches of brown, dying grass, and if you look closely, you’ll be able to see red or pink fungal threads. Additionally, red thread tends to affect lawns during mild spring weather, whereas lawn rust prefers the warm, humid weather of summer and early fall.

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