Dollar spot is a damaging turfgrass disease that is caused by a fungal pathogen which causes dead spots to occur and, according to Wikipedia, is a common concern for golf courses. Dollar spot is typically found on closely mowed grass (hence why it is common on golf courses) and can affect the natural roll of a golf ball, thus posing another large risk to golf courses - aside from aesthetic detraction.

In a news article published by Pennsylvania State University, John Kaminski, professor of turfgrass management and director of the Golf Course Turfgrass Management Program, states, "In the northern United States, more money is spent on fungicides aimed at controlling dollar spot than any other Turfgrass disease...golf courses spend hundreds of thousands of dollars applying fungicides six to nine times a year to control the fungus."

Now, Penn State researchers are claiming that dollar spot is becoming "increasingly resistant to fungicides applied to manage it." In order to understand how dollar spot is resisting the fungicide, researchers collected 681 samples from 45 golf courses and research plots in Pennsylvania, and surrounding states, and tested them for their resistance to chemistries from four different chemical classes. Samples were taken from various management sites, such as greens, tees, fairways and roughs.
https://tinyurl.com/y97qxfp9

The researchers found that dollar spot was actually resisting 41 to 85 percent of the fungicides applied to it. While the Penn State news article does not mention why this is happening, it states that the researchers are hopeful they can work with golf course managers to "fine-tune their programs" and use less fungicide overall.

"If we correctly assess the scope of resistance across Pennsylvania, we can calibrate our management to get the desired level of disease control with fewer inputs," said Kaminski.