Researching Solutions to Fight Dollar Spot

Assistant professor of turfgrass and forage pathology, Dr. Bochra Bahri is studying less costly and more sustainable disease management practices that might reduce the need for fungicides. The research she and her colleagues at the University of Georgia (UGA) Turfgrass Research & Education Center in Griffin have recently undertaken could potentially benefit landscape professionals, golf course superintendents and facility managers as well as the average homeowner

Controlling Dollar Spot

Several projects currently underway involve innovative techniques to reduce disease in turfgrass. “One of the main turfgrass diseases we are working on is dollar spot. It is a major problem in Georgia and the U.S.,” Bahri reported.

“For now there is no released cultivar that is resistant to dollar spot. The only way to manage it is to apply fungicides, which is very costly.” In fact, turfgrass professionals in our region spend more money on chemicals to control dollar spot than for any other disease.

“If you apply a fungicide, there are also risks involved,” Bahri explained. “It may be harmful to the microbial community, ponds and groundwater. It may affect other communities as well, like insects, plants and animals.”

Before a resistant cultivar can be developed, more must be known about the genetics of the pathogen. Bahri is researching the genetic diversity of dollar spot, which is caused by the fungi Clarireedia sp. “There are different species, and I’m working to identify if there is genetic variability within and between species,” she reported. The higher the genetic variability, the more difficult a pathogen is to control.”

If results show that the pathogen possesses high genetic variability, it will mean that the pathogen can more quickly overcome a resistant plant gene and cause disease. However, lower genetic variability in the pathogen could open the possibility for engineering a dollar-spot resistant cultivar.

Bahri is working on another dollar spot project, studying potentially beneficial bacteria with antifungal properties. “We selected one plant endophyte — bacteria that suppress the development of dollar spot. We know it works in the lab to reduce the pathogen development. The goal is to bring this endophyte in the field to see if it helps in controlling the dollar spot.”

The effect of the beneficial bacteria is currently being tested on both zoysia and Bermuda grass on the course at Rivermont Golf Club in John’s Creek near Atlanta.

Additional Turfgrass Research

Bahri is also collaborating with soil microbiologist Dr. Mussie Habteselassie and plant physiologist Dr. David Jespersen on a project to see if nanobubble water, when used to irrigate turfgrass, could help reduce disease. “The rupture of oxygenated nanobubbles have been shown to create reactive oxygen species that have antimicrobial activities and could affect the development of any pathogens,” Bahri explained.

In conjunction with the Georgia Golf Course Superintendents Association, superintendent Mark Hoban has been participating in the nanobubble experiments by applying air-infused water on an TifEagle green at Rivermont Golf Club.

Bahri watches for impacts on the pathogens. Habteselassie analyzes the samples for possible effects on the microbial community in the soil, and Jespersen checks for any impacts on plant physiology.

Bahri appreciates the collaborative culture at UGA. “We all have different expertise, but we are all involved in the same projects,” she pointed out. By working together on a single project, the team can determine not only the effectiveness of a treatment on a disease, but also whether the treatment causes any negative side effects for the plant or the soil’s microbial community. And the results may have a significant impact on the future of turfgrass maintenance.