According to the University of California Integrated Pest Management Program, tall fescue grass is the most common lawn grass in the state of California. Known for its ability to tolerate drought and high heat, tall fescue (Festuca arundinacea) is a cool-season perennial grass that can fall prey to a variety of grass diseases. Inspect your grass regularly to catch signs of disease early so you can apply a fungicide before significant turf damage occurs.
Brown patch is a common turf grass disease caused by a fungus that develops in moisture on your grass. Characterized by the presence of bare, brown sections of grass in your lawn, brown patch is typically more severe during hot, humid summer months. Factors that contribute to brown patch infection include cloudy weather, poor-draining soil, heavy dew, overwatering your lawn and watering your lawn late in the day. Avoid fertilizing your fescue grass with nitrogen in the late spring and summer to reduce your chances of having your lawn develop brown patch; according to the North Carolina State University Department of Plant Pathology, nitrogen produces rich leaf tissue that is more susceptible to the brown patch fungus.
Grass rust fungus typically develops on nutritionally deprived, slow-growing fescue grass during late summer or early fall. Distinctive signs of grass rust in fescue include yellowish-orange or orange-reddish dust spread across the leaves of your grass. These spores easily rub off on your hand when you touch them. Maintaining healthy nutrient levels in your grass is a key preventative step that will help keep your grass growing well and reduces the likelihood of a rust infection. Mowing regularly also can help reduce disease risk.
Like brown patch, pythium blight is a fungus that usually develops after extended periods of wetness in your fescue grass. Common risk factors are similar to those of brown patch, including soil with poor drainage and excessive nitrogen. Pythium blight is characterized by the presence of round, sunken patches of gray-tinged lawn. Often, the leaves in these infected areas are discolored and may look greasy. You can easily spread pythium blight to other areas of your fescue lawn on your mowing and irrigation equipment; dispose of infected grass clippings and wash your lawn equipment before working on uninfected areas of your fescue lawn.
Gray Leaf Spot
This fungus commonly causes severe infections in young fescue grass. It tends to occur more frequently in fescue varieties that are resistant to brown patch infections, according to the North Carolina State University. Signs of gray leaf spot in fescue grass include oval, brown spots on the leaves, which rapidly develop a collection of gray spores. Eventually, the leaves die, creating patches of discolored, greasy grass similar in appearance to pythium blight. Mow your lawn regularly and irrigate early in the morning to reduce gray leaf spot infections in your fescue grass.