It looks like you can see small remnants of explosives on the roots.
Which makes sense as very little at Augusta happens by accident and they often contrive the course set up to get a close finish.
In this case it looks like, as the wind got up, the control bunker was panicking that Rahm would fall back away from Koepka. With no lightning in the immediate area, they fell back to “Operation Fallen Trees”. Full credit to them for pulling it off flawlessly, with the undercover safety crew discretely clearing the area of patrons to prevent injury.