Location

Our neighborhood retention pond has been overcome with Yellow Flag Iris. North of us, two drainage ponds also have the problem. They are now starting to come up. Ours is on the corner of Southwood and Westlake Drive , the other on the corner of Bay Creek Drive and Westlake Drive, the other in between the two.
I have been told that spraying all three ponds makes the most sense as one will infect the other if we don't. All drain into each other, so treating them all at once makes the most sense.