Why is My Grass Turning Yellow and Dying?

Is your once lush, green lawn suddenly fading to yellow and showing signs of distress? Don’t despair! Understanding the potential causes behind this disheartening sight is the first step towards restoring your lawn to its former glory. 

Here’s a breakdown of the usual suspects when it comes to yellowing, dying grass:

Causes of Yellowing and Dying Grass

• Lawn Rust
• Dry Patch
• Chafer Grubs
• Leatherjackets
• Pet Urine

Is lawn rust causing my lawn to die?

Lawn rust can cause your grass to look unhealthy, but it rarely kills the lawn. Lawn rust is a fungal disease that infects the leaves of grass. The visible orange or yellow “rust” is actually spores. While it weakens the grass, it doesn’t directly kill the roots.

• Stressed Lawn: Lawn rust thrives on lawns that are already stressed due to factors like:
  • Drought
  • Heat
  • Poor nutrition
  • Shade
• Temporary Damage: Healthy grass can usually recover from lawn rust once the conditions improve or the fungus is treated. However, if your lawn is already weak when rust hits, it might cause further decline or make your lawn more susceptible to other problems.

How to Tell if Lawn Rust is the Main Issue:

1. The Rust Test: Rub your fingers across the yellowing grass blades. If an orange or yellow powdery residue comes off, that’s a strong sign of lawn rust.
2. Look for Patches: Lawn rust often appears in patches rather than uniformly across your whole lawn.
3. Consider the Season: Lawn rust is more common in late summer and fall.

What to Do To Improve It:

• Improve Lawn Health: Proper watering, fertilization, and mowing will help your lawn resist rust and bounce back faster.
• Fungicides: A fungicide specifically for rust might be necessary in severe cases.
• It Might Not Be Just Rust: If you don’t see clear signs of it, consider other causes of yellowing and dying grass, like those mentioned earlier.

Is Dry Patch turning my lawn yellow?

• Dry patches can definitely turn your lawn yellow. Dry patches are conditions in which the soil becomes hydrophobic—that means it repels water. This can be caused by a waxy coating that builds up from decaying organic matter or fungal activity in the soil.
• Symptoms:
  • Irregularly shaped yellow or brown patches of grass.
  • Water beads up on the surface and refuses to soak in, or it pools before slowly draining away.
  • Soil is bone-dry even just below the surface within those patches.
• Why it’s bad:  Even if you water your lawn, the roots in the dry patch areas won’t get the moisture they need. This causes the grass to become stressed, turn yellow, and potentially die if the conditions aren’t improved.

How to Confirm Dry Patch:

• Watering Test: Try watering the affected area directly. If the water beads up or takes a very long time to soak in, you likely have a dry patch.
• Check the Soil: Dig down a few inches into the yellow patch. If the soil feels completely dry even after watering, it’s further confirmation.

What to Do:

• Aeration: A core aerator punches holes in the dry patch areas, helping water penetrate the soil.
• Wetting Agent: These special surfactants help break down the waxy coating and allow water to soak in better. Follow application instructions carefully.
• Severe Cases: You might need to dethatch heavily or even topdress the area with new soil to improve conditions.

Are Chafer grubs turning my lawn yellow?

Chafer grubs are larvae from chafer beetles (like June bugs). They live in your soil and have a voracious appetite for grassroots. They munch away at the root system of your grass. This prevents the grass from getting the water and nutrients it needs, leading to yellowing, wilting, and patches that die off.

• Signs of chafer grubs:
  • Yellowing, patchy, dying grass
  • Grass that easily pulls up, revealing a lack of roots
  • Increased bird activity on your lawn (they love to feast on grubs)
  • Visible grubs if you dig into the soil (c-shaped, creamy-white with a brown head)
• Additional Damage: Badgers, foxes, and other animals will rip up your turf to get at the grubs, causing even more damage than the grubs themselves might.

How to be sure it chafer grubs:

• The Roll Test: Lift a section of the affected turf. If it rolls up like a carpet, with hardly any roots, grubs are a prime suspect.
• Dig and Look: Examine the soil under the dying patches. Look for those grub larvae.

What to do:

• Nematodes: These microscopic creatures are natural predators of chafer grubs and can be introduced into your soil.
• Chemical Treatments: There are insecticides designed for grub control, but these need to be timed correctly.
• Prevention: Keeping your lawn healthy with good watering practices and fertilization can make it less attractive to chafer beetles for egg-laying.

Are Leatherjackets turning my lawn yellow?

• Leatherjackets are the larvae of crane flies, and they love to munch on grassroots. Like chafer grubs, their feeding disrupts the grass’s ability to absorb nutrients and water, leading to yellowing and potential death.
• Signs of Leatherjacket Infestation:
  • Patches of yellowish-brown, dead, or dying grass, often appearing circular.
  • New grass shoots disappear mysteriously.
  • Increased bird activity pecking at the ground (birds love to eat leather jackets).
  • If you peel back the turf in affected areas, you might see the greyish-brown, legless leatherjacket grubs in the top layers of soil.
• Leatherjackets vs. Other Issues: While yellowing patches can signify several problems, leatherjackets often create these patches in a more circular pattern than others.

How to Confirm Leatherjackets:

The best way to confirm leatherjackets is to take a closer look at the soil beneath the yellowed areas:

• Lift and Check: Carefully lift a section of the affected turf. If you see greyish-brown, legless grubs in the top layers of the soil (around the first inch or two), you likely have leather jackets.
• Soak and Cover: Another method involves soaking a section of the affected area and then covering it overnight with a black plastic sheet. Leatherjackets will come to the surface to avoid darkness, making them easier to spot.

Combating Leatherjackets:

• Natural Methods: If the infestation isn’t severe, encouraging natural predators like birds can help control the population. Keeping your lawn short also discourages egg-laying.
• Nematodes: Introducing microscopic nematodes, natural predators of leatherjackets, into the soil can be an effective control method.
• Insecticides: There are some specific insecticides for leather jackets, but these should be a last resort due to potential environmental impact. It’s best to consult with a lawn care professional for safe and effective application.

Is pet urine causing my lawn to die?

Dog and cat urine contains a high concentration of nitrogen. While nitrogen is a fertilizer, too much in a concentrated area “burns” the grass, much like over-fertilization.

• Salt Matters Too: Urine also contains salts, which can further dehydrate the grass and damage the roots.
• Signs of Urine Damage:
  • Yellow or brown spots, often with a dark green ring around them (this is the area receiving a slightly diluted amount of fertilizer).
  • Spots that occur where your pet frequently urinate.
  • Female dogs often cause more pronounced spots as they tend to squat and release urine in one place, while males may spread it around more while marking.
• Ruling Out Other Causes:  While pet urine is a common culprit for dead spots on a lawn, some other issues can mimic its appearance. Consider:
  • Lawn disease: Some fungal diseases cause similar-looking spots.
  • Insect damage: Pests like grubs could be present.

What to Do about Pet Urine Damage:

• Dilution is the Solution: Immediately hose down areas where your pet urinates. This dilutes the nitrogen and salts, minimizing damage.
• Train Your Pet: If possible, train your dog to urinate in a designated area of the yard, like a mulched section or an area with gravel.
• Supplements: Dog food additives are claimed to neutralize the nitrogen in urine. These have mixed results.
• Reseeding: In severe cases, you might need to reseed damaged patches. If possible, choose a dog-urine-resistant grass variety.

To wrap things up, there are a lot of reasons why your grass might be turning different colors, including different shades of green. By pinpointing the cause, you’ll be equipped with what needs to happen next to remedy the situation so you can go back to having a healthy and happy lawn.