Tall Fescue is the most predominant species selected for home lawns in Kentucky and has many great characteristics such as drought tolerance, good color most of the year, and low input requirements. When compared to other species, tall fescue is the best choice for most home lawns.
With the hottest and typically the driest time of year approaching, disease management often becomes a concern with tall fescue. Rust, Pythium, Grey Leaf Spot as well as others, attack our lawns causing browning leaf blades and often death.
Brown Patch caused by Rhizoctonia solani is one of the most common culprits. As the name implies, brown patch appears as roughly circular patches that are brown, tan, or yellow in color. The patches can range from 6” to several feet in diameter. Brown Patch is closely associated with warm nights and long periods of leaf wetness—either from irrigation or Mother Nature. To make matters worse, turf-type tall fescues, in general, are more susceptible to brown patch than Kentucky 31, one of the first tall fescue varieties released in Kentucky. We prefer these “turf type” varieties for their dense growth form, but these dense canopies of the turf-type fescues retains moisture and humidity for longer periods of time enabling the fungus to spread from plant to plant more easily.
So what is a homeowner to do? Cultural practices are very important part of managing brown patch. Mowing height should be between 2.5 and 3.5 inches; leaving it taller allows the leaf blades to retain moisture longer and cutting it shorter reduces the plant’s ability to produce energy and weakens the grass.
Proper irrigation practice is vital to any disease management plan. When watering your lawn, water early in the morning rather than later in the day or evening. This will allow the leaf blades to dry quickly, therefore reducing the moisture needed for the disease to spread. Always water deep and infrequent instead of watering a little every day.
High levels of nitrogen are preferred by brown patch. Nitrogen induces tall fescue to produce soft, lush leaf tissue that is easily infected by the pathogen. This excessive, lush growth also provides the perfect, moist environment for brown patch to thrive. Generally, fescue should not be fertilized in the summer. Apply nitrogen in the fall, winter, or very early spring.
It should be noted, that there is a wide range of susceptibility within the turf type tall fescue varieties. When establishing your lawn or renovating, choose a variety that has some brown patch resistance. Utilize the National Turfgrass Evaluation Program (www.ntep.org) to determine a resistant variety.
Sometimes, even with good cultural practices, it is necessary to apply fungicides to control brown patch. Contact fungicides, such as chlorothalonil and mancozeb, are short lived, while some newer fungicides, such as the QoIs and carboxamides, provide much longer control. Contact your local extension office for best recommendations.
Submitted by Andrew Rideout, Agent for Horticulture, Henderson Co. Cooperative Extension