I finally got the back cut on one that has been underwater for weeks. Some places were a foot and a half tall. Had to come home and completely decontaminate the mower due to all the doveweed.
That place has cost me quite a few extra trips this year. It's in a low area 5 miles out of town that often sees low temps 8 to 10 degrees lower than we get. If it freezes and goes dormant in November it would be ok with me.