Dr. Philip Harmon is a plant pathology professor and extension specialist at the University of Florida (UF), specializing in warm season turfgrasses...
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Dr. Philip Harmon is a plant pathology professor and extension specialist at the University of Florida (UF), specializing in warm season turfgrasses and southern highbush blueberry diseases. Harmon, a Purdue University graduate, focuses on developing disease-resistant plants and efficient disease management strategies through collaborative research with breeding programs. His extension work provides rapid and accurate diagnostic services to the turfgrass, small fruit and ornamental industries, delivering research-based solutions.
Background
Harmon’s passion for plant pathology began on his family’s fifth-generation farm in southwestern Indiana, where they grew watermelons, cantaloupes and vegetables. “I grew up working in the fields and gained an appreciation for agriculture early on,” he said. Dealing with crop diseases that required weekly fungicide treatments, Harmon’s early experiences sparked his interest in plant disease.
A pivotal moment came when Dr. Rick Latin, an extension plant pathologist from Purdue University, visited the farm as a vegetable and watermelon specialist. Latin shared a Purdue Extension publication with Harmon, igniting his passion for agriculture and later becoming a mentor who guided him through his education. Harmon’s father and Latin also served on a governor-appointed Pesticide Review Board, strengthening the family’s connection to plant disease management.
Harmon attended Purdue University, earning his Bachelor of Science in Plant Science in 1999 and his Ph.D. in Plant Pathology in 2003. "I always knew I wanted to attend Purdue," Harmon reflected, remembering how he had set his sights on the land-grant university from a young age. While pursuing his undergraduate degree, Harmon reconnected with Latin, who had shifted his research focus to turfgrass. After several conversations, Harmon approached Latin about pursuing a Ph.D. in plant pathology. “He told me to come back when I got my degree and sure enough, I did,” Harmon said. "I started right away in his program and pursued a Ph.D. straight out of my B.S."
Research Focus: Turfgrass and Blueberries
As he finished his dissertation, Harmon interviewed for positions and landed two offers from UF. In 2003, he accepted the role he still holds today, focusing on diseases of warm-season turfgrass and managing southern highbush blueberry diseases. His position is split between extension work, research and teaching students, with 60% dedicated to extension. “That was 20 years ago and I still work with both turf and blueberries. It’s been a hoot. It’s been a lot of fun,” he reflected.
Harmon described the blueberry industry as a steady niche market, with breeding programs key to keeping it competitive. However, he acknowledged the challenges of producing a fruit crop in Florida, mainly due to disease pressures and labor. His work with breeding programs for both blueberries and turfgrass is critical to improving resistance.
“The best and most efficient way to deal with disease is to have a plant that doesn't develop it,” Harmon explained. He emphasized that while agrichemical solutions provide immediate control, “long-term, we want grasses and blueberries that don’t require as much pesticide.”
Recently, UF has released several turfgrass varieties that offer excellent disease tolerance, including CitraZoy® Zoysiagrass, CitraBlue® St. Augustinegrass and Brazos™ Zoysiagrass. These grasses help reduce disease pressure and allow growers to push more inputs like fertilizers when needed. Harmon noted that CitraZoy has shown minimal Large Patch Disease, a benefit that gives producers flexibility.
Turf Diagnostic Services
Harmon’s day often begins at the UF IFAS Plant Diagnostics Center, where he works with student diagnostician Alec Dunker, evaluating samples through the Rapid Turf Diagnostic Service. They review findings, examine fungal structures and ensure timely diagnosis. Though Dunker has become self-sufficient, they still collaborate on specialized cases.
Harmon also secures funding through competitive grants and works with chemical companies to develop management recommendations for turfgrass managers, sod growers and golf course superintendents across the state.
When not on campus, Harmon travels to provide extension expertise to county faculty statewide. His outreach includes plant disease awareness and data-supported management strategies to help tackle common turfgrass diseases in Florida.
UF Rapid Turfgrass Diagnostic Service
In 2006, Harmon launched the UF Rapid Turfgrass Diagnostic Service, which now processes about 1,500 samples annually. He credited support from the Florida Turfgrass Association (FTGA) and the Florida Golf Course Superintendents Association (Florida GCSA) Seven Rivers Chapter for helping shape and improve the clinic’s efficiency.
Efficiency has been vital, especially for golf course and turfgrass managers. The clinic also handles samples from the Southeast and internationally. Some samples arrive meticulously prepared, while others, like soil without the plant, can’t provide precise diagnoses. To handle international samples, the clinic uses a quarantine lab with specialized safety features, including HEPA filtration and autoclaves, to prevent any spread of foreign pests or diseases. “We certainly don’t want any new challenges,” Harmon emphasized.
Disease Management and Environmental Conditions
Harmon’s research focuses on integrated approaches to disease management, including testing new chemistries and creating fungicide rotation plans. He noted the shift to single-site fungicides, which are less toxic but need more precision. His team evaluates new products to ensure they effectively address the specific challenges faced in Florida.
Agronomic practices are equally important, helping make grass healthier and less susceptible to disease. Harmon’s approach uses the “disease triangle”—host, environment and pathogen—while collaborating with breeding programs, such as the one spearheaded by Dr. Kevin Kenworthy, a professor in the UF Institute of Food and Agricultural Sciences Agronomy Department, to develop disease-resistant grasses that reduce pesticide use.
In January 2024, unusual weather conditions across Florida stressed turf, making it more vulnerable to disease. Lee and Collier counties saw heavy rainfall, while Palm Beach County experienced a deficit. Due to added environmental stress, these extremes led to outbreaks of Pythium blight and other diseases, typically under control in bermudagrass putting greens. Harmon also noted that these conditions made minor pathogens more problematic, resulting in more sample submissions, particularly from golf courses.
He also highlighted increased testing for Lethal Viral Necrosis (LVN) caused by the sugarcane mosaic virus. The rapid turf diagnostic service has been critical in diagnosing fungal and viral diseases, helping turf managers develop management strategies and address emerging issues.
Lethal Viral Necrosis
LVN has spread across much of southern Florida, with outbreaks reaching as far north as St. Johns County. “We’re still investigating how widespread those are going to become,” Harmon explained. Real-world data from affected communities ensures new varieties don’t develop LVN sensitivity.
While promising research at the Fort Lauderdale Research and Education Center explores RNA interference to disrupt the virus, practical applications are still far off. For now, Harmon’s primary recommendation is to switch to LVN-resistant grass varieties. He also pointed out that cool temperatures trigger LVN symptoms, a factor they can now replicate in lab settings to test new grasses.
New Grass Varieties
Harmon is excited about new grass varieties from UF and other programs but acknowledges the learning curve involved. While new grasses bring favorable traits, they also introduce new pest and disease management challenges. "Sometimes we find that minor pests become major pests,” Harmon shared, explaining that both pathology and agronomy must adapt to new grasses. “There’s no perfect grass,” Harmon admitted, but the goal is to grow these grasses efficiently, optimizing performance and aesthetic value through proper management.
Extension Work
As Florida’s only turfgrass disease specialist, Harmon leverages a network of county faculty and industry associations to extend his work. "I rely on county faculty... and it's been crucial for us with our LVN response," he explained, noting the support from Palm Beach and Miami-Dade counties in communicating issues, solutions and where to send samples.
Harmon collaborates with associations like the FTGA and Florida GCSA to understand industry needs and provide solutions. His extension efforts include presentations, an online "e-library" of turfgrass disease topics and the rapid turf diagnostic service, which allows him to monitor disease trends. “Keeping a finger on the pulse of what disease and turf is doing in Florida has been critical for us to stay ahead of the curve,” he stressed.
Passion for Problem-Solving
Driven by a passion for helping people, Harmon finds fulfillment in supporting golf course superintendents, mentoring students and working with blueberry and sod growers. “Helping folks is what I like the most,” he shared. Despite the challenges, Harmon finds the work rewarding.
Looking ahead, Harmon sees environmental challenges shaping the turfgrass industry, particularly regarding public perception of pesticide use. “Turfgrass serves a very important function... it's still extremely important to our state and to our industries,” he said, stressing the importance of maintaining the industry’s image.
Harmon’s wife, Dr. Carrie Harmon, who leads UF’s plant disease clinic, plays a significant role in his personal and professional life. Together, they enjoy Florida’s natural beauty with their two daughters, often kayaking, fishing and hiking in their free time. Reflecting on his career, Harmon says, “It’s been a great 20 years and I hope to have another 10 or 15 more to continue contributing to the turfgrass industry in Florida.” Grateful for the support and rewarding collaborations, Harmon looks optimistically forward to the future.
This article was written by Sod Solutions Media and Content Manager, Cecilia Johnson. Sod Solutions is celebrating 30 years of successfully developing and releasing turfgrasses with over 20 market-leading varieties like Palmetto® St. Augustine, Celebration® Bermudagrass, EMPIRE® Zoysia and more. Based in Charleston, SC, Sod Solutions is your go-to expert resource for lawn and garden content. For media inquiries and visual materials, email cecilia@sodsolutions.com.