Ascochyta Leaf Blight is a stress-induced fungal disease that usually begins to affect lawns throughout Maryland and Northern Virginia during the late Spring and early Summer.

A lot of lawn diseases and fungus have similar features. Here are six ways to determine whether your Maryland or Northern Virginia lawn is infected with Ascochyta Leaf Blight:

1. Bleached or brown patches of grass
2. Symptoms develop quickly, even overnight!
3. Grass blades look dead in the middle
4. The root and tip of the blade are still green
5. Small, dark brown spots on the blade
6. Appears after weather shifts

Here are some examples of Ascochyta Leaf Blight:

Weather is usually the biggest culprit. Since Ascocohyta Leaf Blight is a fungal disease, it reacts to weather, especially when it alternates between hot, dry periods and cool, rainy conditions.

This disease will spread quickly through foot traffic, weather, and improper watering & lawn mowing practices.

Good news! While this disease looks severe when outbreaks are widespread, it’s actually quite harmless and doesn’t cause any permanent damage to your lawn.

Many common grass types throughout Maryland and Northern Virginia are susceptible, but Kentucky Bluegrass, Tall Fescue, and Perennial Ryegrass are among the most common victims.

Proper watering and mowing is the easiest way to prevent and treat Ascochyta Leaf Blight.

Proper Watering

Watering your lawn properly is key to controlling Ascochyta Leaf Blight. Lawns that are poorly watered are usually more susceptible to this lawn fungus. Our soil scientists always recommend deep, infrequent watering. Shoot for one inch of water once a week. Do not water so much that you have standing water and soggy soil hours later.

To get an idea of how long you should leave your sprinklers running, lay a few empty tuna cans on your lawn, run the sprinklers, and time how long it takes until there’s an inch of water in each can. By filling the tuna can entirely, your lawn will get sufficient moisture into the root.

It is also important to note that lawns that are frequently watered and then suddenly not watered are more susceptible to Ascochyta Leaf Blight because it mimics a quick weather change from cool and wet to hot and dry. So, if you do need to change your watering habit, do so over a few weeks (like if you’re going on vacation, for example).

Proper Mowing

Smart mowing also helps eradicate Ascochyta Leaf Blight. Here are some things to keep in mind:

• Avoid mowing in the morning when the lawn is wet from the dew or last night’s scheduled watering. Instead, mow your lawn in the afternoon when the surface moisture has evaporated.
• Keep in mind that if the grass is wet (from rain or watering), Ascochyta Leaf Blight can easily enter the blades along with the water that enters the wound and allow this fungus to spread.
• Grass that is cut too short is more susceptible to infection. Our soil scientists recommend setting your mower blades to 3.5 to 4.5 inches.