At Lawn Phix, we’re passionate about helping you achieve a healthy, vibrant lawn. Today, we’re talking about Ascochyta leaf blight, a common yet often misunderstood lawn disease. Frequently mistaken for drought stress, this unsightly fungal infection mainly affects cool-season grasses during late spring and summer. Luckily, you can keep your lawn looking its best by understanding what this disease is, what it looks like, and how to manage it.
What is Ascochyta Leaf Blight?
Ascochyta leaf blight is a fungal disease that causes large, irregular patches of grass to turn straw-brown and appear dead, almost overnight. Symptoms of the disease are often mistaken for drought stress. It mostly affects cool-season grasses during late spring and summer, particularly after wet periods.
Will it Kill Your Lawn?
Although it looks scary, Ascochyta blight is relatively harmless and typically causes cosmetic damage rather than killing the grass. Infected leaves and turf may look like they have bleached tips and a “pinched” appearance. You might also notice grass with odd-looking dark brown lesions across the leaf blades. Ascochyta leaf blight can quickly spread across your lawn via watering, mowing, or other activities.
How Does it Develop?
Approximately 80 species of fungi in the genus Ascochyta can cause this often-overlooked lawn disease to develop. This specific type of fungi loves humid, wet weather the most. It also thrives in tall fescue, thick thatch, and lawns with poor soil conditions. Ascochyta leaf blight can also develop and start to spread if you over- or under-fertilize your lawn. Even something as simple as using dull mower blades can contribute to disease development.
Identifying Ascochyta Blight
Here’s how you can spot Ascochyta blight in your lawn:
- Brown Patches: Large patches of your lawn will quickly turn a dull, straw-brown color and appear dead.
- Bleached Tips: Infected leaves often have “bleached” tips with a withered texture.
- Uniform Lesions: Some leaves may develop uniform lesions that affect the entire blade of grass from root to tip.
- Streaking: Visible streaks from lawn equipment like your lawnmower can appear as the fungus spreads through contact from activities like foot traffic, raking, or mowing.
How Does Ascochyta Blight Spread?
Ascochyta fungus survives on dead leaves or clippings that sit on your lawn and drought-stressed turf. During wet weather, spores emerge and are dispersed by water, mowing, and other activities. This fungus enters the grass after you mow and begins to grow from the freshly cut tips toward the leaf base. It can also spread on emerging seedlings as they start to sprout.
Managing Ascochyta Blight
Although Ascochyta blight on lawns looks alarming, it rarely kills your lawn. Instead, these fungal spores typically cause nothing more serious than cosmetic damage. However, we know you don’t want to deal with a brown, dead-looking lawn!
Here are some important ways to manage and prevent this fungal disease:
- Reduce Thatch: Core aerate your lawn at least once a year to reduce thatch and improve water penetration so it doesn’t sit on the top and cause the fungus to spread.
- Maintain Proper Grass Height: Keep your grass height between 2.5 and 3 inches. When the disease is present, reduce mowing frequency and increase mowing height.
- Avoid Mowing During Wet Weather: Frequent mowing of wet grass can spread the fungus and create more infection points. Whenever possible, try to mow your lawn when it’s mostly dry.
- Balanced Fertilization: Avoid applying too much nitrogen fertilizer to your lawn, especially in the spring. Maintain uniform soil moisture and ensure good drainage for more balanced fertilization.
- Regular Mowing Practices: Use sharp mower blades to avoid creating wounds that the fungus can exploit. Dull blades can make this and other fungal diseases worse.
Can You Treat Ascochyta Blight with Fungicides?
Fungicide treatments are generally not recommended for Ascochyta blight. The disease often resolves itself after a few weeks, especially when you implement the lawn care practices we mentioned above. Most lawns affected by Ascochyta blight typically recover within 2 to 3 weeks, depending on the weather conditions.
Recap
Ascochyta blight is a common issue for cool-season grasses, but its impact can be minimized or even completely prevented with the right lawn care practices. By ensuring proper nutrition/fertilization, mowing correctly, aerating annually, and maintaining consistent watering, you can keep your lawn looking lush, healthy, and attractive even during the challenging months of late spring and summer.
At Lawn Phix, we aim to help you achieve the best, healthiest lawn possible. If you have any questions or need further assistance, our lawn care experts and professional turf services are always available to give your lawn the care it needs to thrive.