How to Get Rid of Leaf Spot and Melting Out

Leaf spot

No matter how much you water or fertilize the grass, does your lawn still look like it’s dying? Your lawn might be suffering from the turfgrass diseases leaf spot and melting out. Even worse, your watering habits and fertilizer routine might be encouraging the damage. 

What are leaf spot and melting out, and how do you get rid of them? Our guide will answer all your burning questions about controlling both diseases. But don’t forget to act fast –– if you ignore the problem for too long, melting out will kill your turf. 

What is leaf spot and melting out?

Leaf spot and melting out are two turfgrass diseases that often occur together and have similar symptoms. They were once considered a single disease known as Helminthosporium leaf spot. 

But the diseases are, in fact, separate and caused by the pathogens Drechslera poae and Bipolaris sorokiniana

How to identify leaf spot and melting out

Does your lawn look damaged? Here are some signs that your yard may be suffering from leaf spot and melting out: 

  • From a distance, affected turf appears as diffused areas of tan, off-color grass.  
  • Turf blades develop small, dark brown spots. 
  • As the diseases progress, the lesions enlarge and develop tan centers with brown or purplish-red borders. 
  • The leaf tissue surrounding the enlarged spots begins to yellow. 
  • As the melting-out disease progresses, the fungus attacks the crown and roots. Leaf tissues, such as the leaf sheaths, crowns, rhizomes, and stolons, begin to rot and turn reddish-brown. This phase often results in dead grass. 

What causes leaf spot and melting out?

Who knew a lawn could get sick? When we don’t give our yard the care it needs or perform simple lawn care routines incorrectly, our turf becomes vulnerable to stress, pests, and disease. 

So what could have caused your lawn to develop leaf spot and melting out? Here are some common causes of the diseases: 

  • The diseases are most active during cool, wet weather in spring and warm, wet conditions in summer
  • Excessive nitrogen fertilizer applied in spring
  • Thick thatch
  • Low mowing height
  • Light and frequent irrigation
  • Nitrogen deficiency
  • Shade
  • Poor air circulation
  • Extended periods of leaf wetness
  • Watering the lawn in the evenings
  • Drought stress

How to get rid of leaf spot and melting out

No one likes the thought of a fungus growing in their lawn (unless you’re an avid mushroom hunter). The good news is that you can treat your lawn for leaf spot and melting out. 

The key is to implement control measures as soon as you recognize symptoms. Why? Because once melting out progresses to the roots and crown, effective control may be too late. 

Ready to get your green lawn back? Here’s how you can recover your yard from the turfgrass diseases: 

  • Avoid high nitrogen fertilization
  • Water less often and for long periods. Watering too often and for short periods encourages leaf wetness. 
  • Water early in the morning before 10 am. Watering in the evening is not good for your lawn because the droplet will stay on the grass overnight and create a moist environment. 
  • Raise the mowing height
  • Redirect traffic away from affected turf
  • Remove thatch
  • Apply fungicides at the first signs of leaf spot. Fungicide applications are usually not effective against the melting out phase. According to the PennState extension, fungicides containing iprodione, chlorothalonil, mancozeb, fludioxonil, azoxystrobin, or penthiopyrad typically provide good leaf spot control. 

How to prevent leaf spot and melting out

Once you clear your lawn of leaf spot and melting out, you won’t want to deal with the hassle ever again. 

The best way to prevent turf disease is to keep your lawn well maintained. To prevent leaf spot and melting out specifically, here are some management practices to prioritize: 

  • Apply nitrogen fertilizer in the fall. Yards with too much fertilizer in spring are more susceptible to leaf spot and melting out. 
  • Avoid scalping your lawn. Cutting the lawn too short stresses your turf and exposes the crowns and roots to infectious spores. 
  • Maintain proper irrigation practices that don’t encourage prolonged leaf wetness. 
  • Apply preventative fungicides when the diseases’ favorable weather conditions arrive.
  • Increase sunlight in shady areas by trimming and pruning nearby plants. 
  • Increase air circulation by trimming and pruning nearby plants. 
  • Remove excessive thatch that may be harboring dormant fungi. 

What grass types are most susceptible to leaf spot and melting out?

Leaf spot and melting out affect a wide variety of turfgrasses. Kentucky bluegrass, perennial ryegrass, and tall fescue are the most susceptible to the diseases, but many disease-resistant cultivars are available. Bermudagrass and Zoysiagrass are also vulnerable to leaf spot and melting out. 

FAQ about leaf spot and melting out

1. What other turf diseases can infect my lawn?

Your lawn is vulnerable to an abundance of diseases (and pests–– yikes!). If leaf spot and melting out were the only diseases you had to protect your lawn from, yard work would be much simpler. Fungal diseases to remain mindful of include:

Brown patch
Dollar spot
Fairy ring
Gray snow mold 
Pink snow mold 
Powdery mildew
Red thread
Summer patch

2. How do I prevent grass diseases in my lawn?

The secret to keeping fungal diseases out of your lawn isn’t fungicide –– it’s good lawn care. Fungicides certainly help in the preventative process, but they shouldn’t be the only method you rely on. 

Fungicide might combat diseases, but they don’t build your lawn’s strength and resilience. Only good lawn maintenance can improve your lawn’s health and strength. And the healthier the grass, the less vulnerable it becomes to disease. 

Here are 15 lawn care treatments that will help your lawn grow healthy and beautiful: 

Remove leaves and other debris from the yard. Lawn debris can weaken your lawn by blocking the turf’s access to sunlight. Many fungal diseases also will remain dormant in plant debris. 
Mow the grass regularly (and correctly). Mowing too low may scalp your lawn. Allowing your grass to grow too tall creates an attractive environment for diseases and pests. Never cut off more than ⅓ of the leaf blade at a time; otherwise, you will stress your turf. 
Leave behind grass clippings. Grass clippings are healthy for your lawn. Grass clippings help retain moisture in the soil and add nutrients as they decompose. However, do not leave behind diseased grass clippings.  
Perform proper irrigation practices. Improper watering may lead to extended leaf wetness and weak root systems. Remember to water infrequently and for long periods. Water in the early morning before 10 a.m. 
Invest in a sprinkler system. Watering the lawn can be a daunting task. Why not hand the job over to an automatic sprinkler system? Your yard won’t ever miss a watering, and you needn’t wake up at the crack of dawn. 
Plant grass seed that’s disease-resistant and suitable for your lawn. Some grasses are going to grow better than others, depending on where you live. Talk to a local lawn care professional about whether you should plant warm- or cool-season grass and discuss options for disease-resistant varieties. 
Test your soil. A healthy lawn needs healthy soil. A soil test reveals what nutrients your soil is lacking and how you can make amendments. 
Fertilize your grass. After a test reveals what nutrients your soil needs, create a fertilization regime for your lawn. 
Aerate compact soil. Core aeration relieves compact soil by making small holes in the ground. This process allows water, oxygen, and nutrients access to the root system. 
Remove thatch that exceeds ½-inch thick. Thatch is the dead organic matter that builds up between the turf and soil surface. A thin thatch layer is good for the lawn, but a thick layer is attractive to fungi. 
Overseed the lawn. Routine overseeding keeps the lawn dense and green. No more thinning or bare patches!
Remove existing weeds. Not only is a weed invasion unsightly, but it’s also stressful for your turf. Your lawn must expend energy competing for space, nutrients, sunlight, and water when it could be using its energy to grow healthy instead. Remove weeds with a post-emergent herbicide or pull them by hand. 
Apply pre-emergent herbicide. If weeds return to your lawn year after year, consider spraying a pre-emergent herbicide to block their growth. 
Control grubs and other pests. Grubs live underneath the soil surface and feast on the turf’s root system. 
Spread compost across the lawn. Compost is a nutritional organic fertilizer. Rake a compost top dressing across the yard or brew a compost tea and spray it on the grass. 

3. What if I can’t identify the fungus on my lawn?

Correct identification of a fungal disease is important. If you misidentify the fungus that’s killing your grass, then your control measures may not prove effective. Why? Because the control methods that work for one turfgrass disease are not guaranteed to work for other diseases. 

Identifying a fungal disease isn’t always easy. Many lawn diseases have similar symptoms, and some even mimic common turf injuries, such as drought or heat stress. If you don’t recognize the fungus in your lawn, consider contacting a local diagnostic lab or turfgrass pathology lab to receive an accurate diagnosis of your infected turf. 

Sweating over fungus? Turn to the pros

From mowing the lawn to removing thatch, fungus control can take hours of yard work. Why lose your whole weekend to a stubborn fungus when you could be spending it with people you love? 

When fungus control starts to eat up your time, hire a local lawn care professional. Not only can lawn care pros help cure your lawn, but they also can help prevent outbreaks from reoccurring. Hand the power rake and watering hose over to the pros and wave goodbye to the fungus. 

Main Photo Credit: Shutterstock

Jane Purnell

Jane Purnell is an artist, writer, and nature lover. She enjoys teaching readers about the importance of eco-friendly lawn care, integrated pest management, biodiversity, and sustainable landscaping.