Thought I'd report back in with results. I applied 8 oz of Sonar 9/1 and 4 more ounces on 9/8. Today the watermeal is nearly all gone. What is left is very sparse and broken up. I expect it'll all be gone in a week or two.
Here are two links to White cap sources. Although just to be clear I used Sonar.
White Cap White cap
