Fine fescue is a cool-season turfgrass that is popular with homeowners whose lawns get both sun and shade. This is due to its high tolerance to shade and low-maintenance qualities. Although it is less susceptible to fungal diseases than other cool-season turfgrasses, it is not completely unaffected by them. Here, we’ll discuss a few of the common diseases found in fine fescue.
What is fine fescue?
Fine fescue is a humidity-loving cool-season turfgrass. There are actually five types in the fescue family: chewings fescue, hard fescue, sheep fescue, slender creeping red fescue, and strong creeping red fescue.
They’re considered low-maintenance, requiring less fertilization and mowing and are less susceptible to disease than other turfgrasses. Oftentimes, fine fescue is mixed with another cool-season turfgrass, such as Kentucky bluegrass. This works well in lawns that have both sunny and shaded parts, where fine fescue is able to thrive in the shaded parts and the other turfgrass can thrive in the sunny areas.
Common diseases
Red thread
Signs and symptoms:
Red thread can cause major cosmetic damage and is the most common disease found in fine fescue turfgasses. Lawn mixes, which commonly contain strong creeping red fescue, often see problems with red thread. You may spot it in your fine fescue turfgrass during rainy periods in spring, fall, or summer.
Symptoms appear as pink, circular or irregular patches on your lawn, ranging from four inches to two feet in diameter. Soon, your turfgrass will be covered in red thread-like strands called mycelium. Eventually, your fine fescue will die out and the color will fade.
Conditions:
Red thread is caused by the fungus Laetisaria fuciformis.
It’s more severe during spring and fall, in long periods of cool, wet, overcast weather. These conditions help slow growth of fine fescue turfgrass and favor growth of the pathogen.
Red thread can develop at any time of the year, due to its wide temperature tolerance, as long as the turfgrass is in a period of slow growth and sufficient moisture is present.
Management:
- Fertilize to maintain vigorous growth. Ensure recommended amounts of phosphorus, potassium, lime, and nitrogen are present in your soil.
- Irrigate in the early mornings to prevent long periods of leaf moisture. Water enough to wet the entire root zone and re-water at the first sight of drought stress.
- Remove barriers, such as any structures, trees, or shrubs, to increase aeration and sunlight penetration.
- Remove any diseased clippings, when red thread is active, to reduce red thread’s spread.
- Use resistant cultivars of fine fescue to prevent red thread.
Leaf spot
Signs and symptoms:
Leaf spot can occur in fine fescue during the spring and late summer months. It becomes most active on stressed or poorly maintained turfgrass.
Initially, small dark spots appear on the leaves. As the spots grow, brown or purplish-red borders appear around tan centers. Then, the spots grow so big that the entire leaf turns tan or brown.
Conditions:
Leaf spot is caused by the fungus Drechslera spp. and Bipolaris spp.
Extended periods of wetness can lead to leaf spot in fine fescue, especially in cooler climates.
Infrequent mowing at low cutting heights, light and frequent watering, and excessive nitrogen, particularly in the early spring, can all cause leaf spot development.
Management:
- Raise the mowing height in July and August.
- Use a slow-release fertilizer. Provide your turfgrass with a sufficient amount of nitrogen to maintain a moderate growth rate through the season. However, avoid excess nitrogen in the early spring.
- Irrigate to avoid drought stress. Early morning waterings work best to minimize leaf wetness.
- Use cultivars of fine fescue that resist leaf spot.
Dollar spot
Signs and symptoms:
Dollar spot is active through the growing season, especially with excess dew in the air and low soil moisture.
This disease is characterized by small white or light tan lesions with reddish-brown borders.
Often, you’ll find fuzzy, white mycelium on the turfgrass in mornings when dew is present. A large number of spots can form together to create larger dead areas in the turfgrass.
Conditions:
Dollar spot is caused by the fungus Clarireedia jacksonii.
Dry soil, coupled with extended periods of moisture on leaves, create ideal growing conditions for dollar spot. Low nitrogen levels can also contribute to its growth.
Management:
- Water to increase growth if soil is dry while also minimizing the time that leaves are wet.
- Mow the grass regularly.
- Avoid nitrogen deficiencies.
- Use resistant cultivars of fine fescue to prevent dollar spot.
Summer patch
Signs and symptoms:
Summer patch can be found on fine fescue turfgrass in late July and August. It appears as irregular shaped, dark, wilted spots. These spots range from just a few inches to a few feet in diameter.
Outer edges of the circle or patch turn brown, with tufts of healthy turfgrass sometimes appearing in the center. Individual plant roots dry out and decay.
Conditions:
Summer patch is caused by the soil-borne fungus Magnaporthe poae.
This fungus can develop in poor quality, compacted soil and excessive thatch, infecting roots in warm, wet soils.
Low mowing, frequent irrigation, and a high Nitrogen content provide optimal conditions for summer patch to develop.
Management:
- Irrigate to a depth of three to four inches in the summer, and allow the soil to dry out between waterings.
- Raise the mowing height to promote better root development and provide nutritional reserves to aid the turfgrass during stressful periods.
- Use a slow-release fertilizer. Annual nitrogen fertilizer should be applied in autumn and early winter.
- Renovate the damaged areas with resistant fine fescue cultivars to prevent summer patch. Alternatively, you can inter-seed more resistant turfgrasses, such as perennial ryegrass, with your fine fescue turfgrass.
Powdery mildew
Signs and symptoms:
Powdery mildew appears as white or gray-colored spores on the leaf’s surface that doesn’t easily rub off. Fine fescue leaves may eventually yellow, and the turf will thin out.
Conditions:
Powdery mildew is caused by the fungus Blumeria graminis.
Moderate to high humidity and shade, as well as poor air circulation, provide optimal conditions for powdery mildew.
Management:
- Reduce the amount of shade that your turfgrass receives.
- Increase the air circulation by reducing any large structures, trees, or shrubs that may block the wind.
- Use resistant cultivars of fine fescue to prevent powdery mildew.
Frequently Asked Questions
It will not go away on its own. Treatment may vary depending on the fungus, but practicing good turf management can help tremendously in preventing lawn disease and pests.
Knowing which disease is affecting your grass is important in determining what steps need to be taken to get rid of it. If you’re having trouble identifying the fungus affecting your lawn, your local state universities will have a lab that specializes in the diagnosis of turfgrass diseases. You can always contact the university, or any other local diagnostics lab or turfgrass pathology lab.
Reach out to your Lawn Love lawn care professionals for further assistance if you’re having trouble determining which diseases are affecting your turfgrass. They will be able to figure out the right remedy to bring your lawn back to its healthiest, disease-free state.
Main photo credit: Aaron Patton | Purdue University
