Ascochyta Leaf Blight

Ascochyta Leaf Blight triggered by tires

Lawn Disease Alert: Ascochyta Leaf Blight

In this post, we will discuss Ascochyta Leaf Blight, how to identify it, the conditions which it appears in, and how to treat and control Ascochyta Leaf Blight.

What is Ascochyta Leaf Blight

Ascochyta Leaf Blight is a fungal lawn disease which can cause brown patches of grass to appear very quickly on lawns after periods of drought followed by heavy rain.
It most frequently appears in lawns during June or July because during these months the weather conditions make lawns susceptible. For the fungus to thrive, it needs a period of heat and drought, followed by heavy rains.
If you have a period of summer where there is no significant rain for a few weeks and then you have a heavy rainstorm or a few days of rain, it can create the conditions for Ascochyta Leaf Blight to emerge.
Ascochyta Leaf Blight can appear very quickly, seemingly overnight on otherwise healthy lawns. The fungus can be present in your lawn but it will not be noticeable until the right weather conditions appear.
Ascochyta Leaf Blight - tire track patchesBrown patches that look like tire tracks
Have you noticed brown patches on your lawn that look like tire tracks? This is very often a symptom of Ascochyta Leaf Blight. It’s likely the fungus was present in your lawn and then when it when it was mowed, the mower pushed spores to other parts of the lawn. You may then notice brown lines in the lawn in the areas where the mower wheels met the grass.
Types of grass affected by Ascochyta Leaf Blight
Ascochyta Leaf Blight may affect lawns in the Chicagoland area because this fungus will appear on some of the most popular types of grass in Northern Illinois. In particular, it will affect Kentucky Bluegrass, which is the most common grass in most Chicago area lawns.

  • Kentucky bluegrass
  • Tall fescue
  • Perennial ryegrass

Identifying Ascochyta Leaf Blight

The symptoms of Ascochyta Leaf Blight will create brown patches in the lawn, which make it easy to confuse with many other lawn diseases and issues such as grub damage. It also shares symptoms with stress caused by drought, which can make the identification more difficult.
If you see the patterns from your mower wheels on the lawn, it is likely to be Ascochyta Leaf Blight.
Inspect blade for signs of Ascochyta Leaf Blight

The other way to identify Ascochyta Leaf Blight is to inspect the blades of grass more closely. It may be helpful for you to use a magnifying glass so you can look closely at the top of the grass leaf blade.
Look for blade tips with tiny yellow to dark brown, flask-shaped fruiting bodies scattered on discolored grass blades. The leaves will often show a bleached tip dieback that extends about a third to halfway down the leaf blade. The margin between healthy and diseased tissue is abrupt and slightly pinched, with a dark brown to purple banding that is generally wider than that associated with dollar spot. Sometimes spots with distinct borders occur elsewhere on leaf blades. In other cases, leaves may exhibit white banding or be entirely collapsed and shriveled
Ascochyta Leaf Blight often confused with

  • Dollar spot
  • Heat stress
  • Moisture stress
  • Mower injury
  • White grub damage

Treatment of Ascochyta Leaf Blight

The good news is that this fungus only infects the leaves of grass but not the crown or root system. With minor treatment, the grass can recover and can be looking green again in just a couple weeks.
Use a fungicide on your lawn to stop the spread of  Ascochyta to other parts of your lawn. This will also stop it in the already infected areas on your grass as well.
After you have applied fungicide, make sure to use proper watering and mowing routines on your lawn. The combination of fungicide, watering, and mowing should be all you need for it to recover.
Related: Lawn mowing tips

Prevention of Ascochyta Leaf Blight

Like many lawn issues, good lawn care maintenance can help stop Ascochyta Leaf Blight in the first place.

  • Keep your lawn fertilized at the proper times.
  • Make sure that you don’t have too much thatch in your lawn.
  • Perform core aeration on your lawn each fall
  • Don’t mow your grass too short
  • Keep mower blades sharp
  • Water evenly across lawn
  • Perform a weekly deep watering during summer drought

We hope this post will help you out with identifying, treating and preventing Ascochyta Leaf Blight. Keep your lawn looking great!




From lawn disease treatment to fertilization , grub control, aeration, overseeding and more, we will make your lawn look beautiful!
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2018-04-13T13:43:25+00:00 Lawn Care, Lawn Diseases|