PGA Tour commissioner Jay Monahan issued the warning on Tuesday after the latest incident in the unedifying spat between the Ryder Cup team-mates on Sunday.
DeChambeau reacted angrily to a cry of “great job, Brooksy” after losing a play-off for the BMW Championship to Patrick Cantlay.
A number of spectators were previously escorted from Muirfield Village during the Memorial Tournament in June for shouting “Brooksy” at former US Open champion DeChambeau.
Four-time major winner Koepka, who was not competing, reacted to the news by posting a video on social media offering to reimburse any spectator whose day was “cut short” with a free case of beer.
That came a fortnight after leaked footage showed Koepka being unable to contain his dislike of DeChambeau after being distracted by his compatriot during an unaired interview at the US PGA Championship.
Speaking ahead of the season-ending Tour Championship in Atlanta, Monahan said that “pent-up demand” to watch live sport during the coronavirus pandemic had played out in an “ugly way” in various sports.
“We have to be intentional about our expectations for fan behaviour and I believe our fan code of conduct does that,” he said.
“By coming to a PGA Tour event, you’re expected to contribute to a welcoming and safe environment by refraining from and reporting any unsafe, disruptive, or harassing behaviour.
“Comments or gestures that undermine the inclusive and welcoming nature of the game will not be tolerated, nor will any harassment of players, caddies, volunteers, officials, staff or other spectators.
“Fans who breach our code of conduct are subject to expulsion from the tournament and loss of their credential or ticket.”
Asked specifically if shouting “Brooksy” at DeChambeau would constitute harassment, Monahan said: “Yes.
“And the reason I say yes is the barometer that we are all using is the word respect, and to me, when you hear ‘Brooksy’ yelled or you hear any expression yelled, the question is, is that respectful or disrespectful?
“That has been going on for an extended period of time. To me, at this point, it’s disrespectful, and that’s (the) kind of behaviour that we’re not going to tolerate going forward.”Jump to next article