Research conducted at Penn State as a masters degree project for a former golf course superintendent has shown that some of the products applied to golf course turf to control many common diseases could be damaging to cool-season fairways.
In the study, the research team tested a total of nine demethylation inhibitor fungicides used to manage a variety of turfgrass diseases, for their effects on creeping bentgrass and annual bluegrass turf maintained at fairway height. The results of the two-year study provide superintendents with more information on which chemistries can be used effectively and without damaging turf.
Results of the project showed that metconazole and triticonazole resulted in damage to annual bluegrass but was not injurious to creeping bentgrass. Mefentrifluconazole, another fungicide in the study, resulted in the lowest threat of injury to annual bluegrass and creeping bentgrass.
Conducted in 2020 and duplicated the following year, the study was the master's project for PSU grad student Maureen Kahiu (right), a former golf course superintendent in her native Kenya who is currently working toward a doctorate degree at the University of Tennessee. The results were published recently in the online edition of International Turfgrass Society Research Journal.
This research was the result of a need to get a better understanding of the relationship between golf course turf and commonly used DMI fungicides, according to John Kaminski, Ph.D., professor of turfgrass science at Penn State.
"While these products are highly effective for disease control, their potential to cause injury to different turfgrass species — especially under varying environmental and management conditions — hasn't been systematically studied," Kaminski said. "Golf course superintendents have long relied on anecdotal experience or manufacturer guidance, but there’s been no side-by-side comparison that puts all of these fungicides through the same testing protocols.""
Two field trials were conducted in 2020 on research fairways at Penn State's Valentine Turfgrass Research Center. Nine fungicides — propiconazole, triadimefon, myclobutanil, mefentrifluconazole, pydiflumetofen, flutriafol, tebuconazole, metconazole and triticonazole — were applied in 14-day intervals over three summer months. The trials were replicated in 2021.
"Our study is the first to directly compare a broad range of DMI) fungicides on both annual bluegrass and creeping bentgrass," Kaminski said. "We focused on real-world application scenarios to make the findings immediately useful to superintendents. The results help clarify which products are more likely to cause phytotoxicity on specific species and under what circumstances, providing actionable guidance for choosing safer options without sacrificing disease control."
Kahiu's research was partially funded by the Paul R. Latshaw Graduate Fellowship. In the study, she applied all the fungicides to the research fairways with a backpack hand sprayer. To determine any phytotoxicity caused by the fungicides, she examined the plots on a daily basis, looking for changes in color, texture, density and growth.
"Anywhere you go in the world, when it comes to turfgrass management, Penn State is where you want to be," Kahiu said. "It's known as the best internationally."
