What Are the Blue Rings AAround the Bunkers on Newport?

We have treated the bunker faces on Newport with RoundUp.  We mixed a 1/4% solution (half the lightest label rate) with some colorant and hand sprayed the zoysiagrass around the bunkers.  We are trying to kill all the winter and perennial weeds and cool season grass in the zoysia.  It is perfectly safe, I have done this before.  We are also trying to preserve and recreate the nice clean edge that was present when Newport was redesigned in 1998. 

Stay tuned...tomorrow we are spraying RoundUp on the Newport fairways..............WHAAAAAAT you say?  Stay tuned.