New Thinking: How Should Fertility be Used to Manage Brown Patch Disease in Tall Fescue Lawns? TSU Field Day
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From the President
Ozzy Lopez
My fellow nurseryman and landscapers, we’ve made it through another chaotic shipping season together. Our members live and breathe the TNLA motto everyday: we are hardworking people serving hardworking people in the green industry.
We have several big events coming up soon. The annual TNLA Field day hosted by the University of Tennessee Institute of Agrilculture at UT Gardens on the Knoxville campus will be held on June 12th, 2025. Please go to our website https://tnla.com/ and click on the “Events” tab for more information and registration details. In October, we are excited to see the return of our favorite trade show in Tennessee, TNGRO 25, at the Farm Bureau Expo Center in Lebanon, Tennessee. Exhibitors, please be sure to secure your booth space as soon as possible. Sponsors, we would love to hear from you soon as well. You all are the reason that our events are such a success. We will have some informative speakers on various topics as well as our annual business meeting and awards ceremony on site on Thursday, October 23rd during the TNGRO show. For registration information please click on the link provided https://tnla.com/TNGRO We are also looking into holding our annual golf classic at Pine Creek golf course in neighboring Mt. Juliet on the Saturday after the show. Stay tuned there is more to come.
We want to share some good news, please join me in congratulating our Memorial Scholarship award recipients, Emmalyn Kinsey from east Tennessee and Kenley Roark from north central Tennessee. Both will be presented the $1,000 TNLA Memorial Scholarship at their High School awards ceremony. In other news of interest, we are aware of the current movement by the state legislature to put Bradford pears on the invasive species list, commonly known as the “pear ban.” We have contacted State Senator Bowling and State Representative Sherrell with our concerns. We also met with representatives from the Tennessee Department of Agriculture to discuss technical details about the timing and language of any such bill. Currently the issue has been sent to UTIA for a plant survey and will proceed from there. We will stay engaged in this process to advocate against any sudden changes or overly broad language, particularly restricting understock used for fruiting pears. As many of you are aware, this issue comes up every 5 to 10 years. This time they are taking the correct procedural steps and putting it through regular order. The movement is gaining momentum with several other states already implementing pear bans and the survey data is likely to say what we all suspect. Our best advice is to plan for some type of restrictions on ornamental pears in the next three to five years.
Thank you for the opportunity to serve as your president. We hope to see you in Knoxville at the field day and Lebanon at TNGRO this year. If you want to serve on the board or a committee, please contact our Executive Director, Danae Bouldin, at (931)473-3951. And please don’t forget to register for the Field Day and sign up for TNGRO. See you soon!
Ozzy Lopez TNLA President
The Tennessee Greentimes is the official publication of
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Published By Leading Edge Communications
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Editors
Dr. Bill Klingeman
Dr. Amy Fulcher
Associate Editors
Dr. Karla Addesso
Dr. Becky Bowling
Dr. Midhula Gireesh
Dr. Nar Ranabhat
TNLA Officers
President Ozzy Lopez
Ozzy’s Lawncare and Hardscape Services
1st Vice President
Sam Kinsey Kinsey Gardens
2nd Vice President
Trista Pirtle
Pirtle Nursery
3rd Vice President
Jason Peace
Home Nursery, Inc.
Secretary-Treasurer
Bryan Tate
Mid-South Nursery
Associate Director
Eli Eldridge
H&R Agri-Power Farm & Turf
Ex-Officio
Jon Flanders
Botanico, Inc. & 3F - Flanders Family Farm
Executive Director
Danae Bouldin
Pictured here are TNLA 1st Vice President Sam Kinsey, and TN FFA President, T. Wayne Williams, presenting the award to winner, Douglas Farney from the Covington FFA Chapter.
Index of Advertisers
Bowling’s Nursery, Inc. 9 www.bowlingsnursery.com
Brown’s Nursery 5
Cam Too Camellia Nursery, Inc. 7 www.camtoocamellia.com
Doug Young Nursery 11 www.dougyoungnursery.com
Hoover & Son Insurance 14 www.hooverins.com
John Holmlund Nursery 10 www.jhnsy.com
King’s Industries Back Cover Leading Edge Communications 3 www.LeadingEdgeCommunications.com
Motz & Son Nursery 14 www.motzandson.com
Richey Nursery Company, LLC 14 www.richeynursery.com
Rusty Mangrum Nursery 13 www.rustymangrumnursery.com
Stowers Machinery
Corporation Inside Front Cover www.stowerscat.com
Tennessee 811 .......................................... 13 www.tnonecall.com
The Turf Zone 14 www.theturfzone.com
Turner & Son’s Nursery 13
How Should Fertility be Used to Manage Brown Patch Disease in Tall Fescue Lawns?
By Dr. Brandon Horvath, Professor, Turfgrass Pathologist, UT Plant Sciences
Tall fescue is a prominent lawn grass choice especially in the Middle and Eastern Tennessee regions where cool-season turfgrasses are more prevalently used. Brown patch, caused by Rhizoctonia solani, is the most damaging pathogen affecting tall fescue lawns throughout Tennessee. This fungal disease can transform a lush, vibrant lawn into a patchy, unsightly expanse when conditions favor disease development.
While fungicide applications are often necessary for severe outbreaks, proper fertility management serves as the foundation of an effective preventative strategy. Fertility practices directly influence plant health, disease susceptibility, and recovery potential. Unfortunately, many common fertilization practices can actually make the problem worse. Supported by several years of research findings, we have recently employed a different approach that maintains some growth turfgrass potential via fertility that enables infected plants to recover following disease pressure. Understanding the relationship between fertility inputs and disease development will allow lawn care professionals to implement proactive management programs that reduce disease severity while maintaining a quality turfgrass stand. This article explains how different fertility approaches affect brown patch in tall fescue lawns and provides practical ideas for turfgrass managers to implement these approaches in a lawn care setting.
Understanding Brown Patch Disease
Pathogen Biology and Life Cycle
Rhizoctonia solani is a soilborne fungal pathogen that is present in most turfgrass environments. The fungus survives unfavorable periods as mycelia in thatch and soil. Under specific environmental conditions, primarily with high temperature and humidity, the fungus becomes active and begins to attack the plant.
In tall fescue, R. solani primarily infects the leaf blades and sheaths, creating lesions that eventually result in a circular “patch” appearance. The fungus spreads via mycelial growth, moving from plant to plant through direct contact (Figure 1). Unlike other turfgrass diseases, brown patch does not spread via spores.
Figure 1. Brown Patch infecting tall fescue lawn, note the mycelia of the pathogen spreading from leaf to leaf.
Environmental Triggers in Tennessee
Tennessee’s climate creates ideal conditions for brown patch development during much of the main growing season. The Brown Patch pathogen becomes active in response to:
• Temperature thresholds: Nighttime temperatures that consistently remain above 65°F with daytime temperatures between 80–85°F. These conditions typically develop in TN from midMay through September, sometimes persisting into October.
• Humidity factors: Relative humidity that exceeds 80% greatly increases infection rates. Our humid summer climate, especially during nighttime, will frequently exceed this threshold.
• Leaf wetness: Extended leaf wetness periods of 10+ hours dramatically increases infection rates. Evening irrigation practices, frequent summer thunderstorms, and morning dew are common in Tennessee and contribute to this risk factor.
So, it is under these conditions that the plant becomes most susceptible to fungal attack and infection. Historically, conditions coincide with timing of when recommendations suggest backing off on fertility applications to allow the plant to “harden off”. However, our work has shown that a plant that is not able to actively recover will be in a worse position as multiple rounds of disease take place and decimate the stand.
Nitrogen Management and Brown Patch Susceptibility
Nitrogen is the most important nutrient for proper turfgrass growth, and there is a direct and significant impact on nitrogen management with brown patch susceptibility in tall fescue. Traditionally, research has shown that water-soluble, quick-release nitrogen sources (such as urea, ammonium sulfate, and ammonium nitrate) significantly increase brown patch severity compared to slow-release formulations. The main reason for this effect has been that at higher doses, the plant grows more rapidly, resulting in a thinner cuticle and lush, succulent growth. Modern practices, however, allow for much lower application rates of N fertility, and a spoon-feeding approach can often improve turfgrass performance.
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Using controlled-release nitrogen sources like polymer-coated urea will deliver nitrogen more gradually (Figure 2), which in turn will reduce disease-prone succulent growth while maintaining adequate plant growth for recovery. This relationship is really the key to using fertility to help manage the damage caused by brown patch. Ideally, the turfgrass manager wants the plant to grow just enough that when conditions aren’t conducive for disease, the plant will grow out of the symptoms and recovery will take place. When that condition exists, the turfgrass plants will be capable that when exposed to another disease cycle, some damage will occur, yet recovery will again take place.
Application Rate and Timing
Under-fertilizing a turfgrass stand or lawn is much more common today than over-fertilizing. As long as the applicator avoids excessive nitrogen application during high-risk periods, one of the most common fertility mistakes that often leads to more severe brown patch outbreaks can be avoided. By providing the plant with “just enough” fertility, the need for plant growth can be balanced with not overstimulating the pathogen’s ability to attack. I began to change my own perspectives on these recommendations about a decade ago, when some of our research clearly demonstrated that having moderate fertility applied during the growing season led to lower brown patch severity and also a decrease in undesirable competition from bermudagrass encroachment. As a result, I began making some adjustments in my recommendations on fertility:
• Late Spring (April-May): Limit applications to 0.5-0.75 lb N/1000 sq ft using primarily slow-release sources as temperatures begin to approach the brown patch threshold. Alternatively, one could use a very slow-release poly coat urea, that would provide ~3 lbs N/1000 sq ft for the April-August Period (~20 wks)
• Summer (June-August): Make low rate applications (0.1-0.2 lbs N/1000 sq ft; ~0.6-1.2 lbs N/1000 total for 3 months) during the highest risk brown patch season. These applications are made to just maintain some turfgrass growth and recovery potential without sparking lush succulent growth. Slowrelease sources can also be used.
Figure 2. Slow N release curve of a Polymer Coated Urea fertilizer showing a 20+ week release of N (Data source: Harrell’s Polygraph, 1.75lbs N/1000, April application, Knoxville, TN).
• Early Fall (September): Use fertilization at 0.75-1.0 lb N/1000 sq ft as temperatures moderate to focus on turfgrass recovery from summer stress and disease pressure.
• Late Fall (October-November): Apply 1.0-1.5 lb N/1000 sq ft, emphasizing root development and carbohydrate storage.
In total, here in Tennessee, managers should target about 4-5 lbs of N/1000 sq ft/year for a quality Tall Fescue lawn. Making these slight adjustments in how we fertilize will help reduce the damage caused by disease while allowing for turfgrass recovery throughout the season, maintaining turf quality.
Conclusion
Effective brown patch management in tall fescue lawns requires an “allhands” approach centered around proper fertility practices. By understanding the relationship between nutrition and disease development, lawn care professionals can significantly reduce brown patch severity while maintaining acceptable turf quality.
Key takeaways include:
1. Timing is critical: Avoid quick release, high rate, nitrogen applications during high-risk periods (June-August in Tennessee)
2. Source matters: Use slow-release sources to smooth out N release over time mimicking a low rate “spoon feeding” approach
3. Integrate approaches: Coordinate fertility with appropriate cultural practices and if needed, fungicide interventions
4. Prevention focus: Implement proactive programs rather than reactive treatments
Using these research-based fertility practices, I’m confident that turfgrass and grounds managers can significantly reduce the impact of brown patch in client and home landscapes while promoting healthier, more resilient tall fescue lawns.
Figure 3. Research plots showing the effect of a single spring Polymer Coated Urea (3 lbs/1000, Gal Xe One, Simplot) application vs. monthly applications of Urea (1lb/1000) and regular applications of a fungicide for brown patch control. Most of the off-color turf is infested with brown patch damage.
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