If you have ever seen them spraying to kill back weeds and pads it looks like they are using a fire hose to spread the weed killer. I am not sure how it affects the fishing but it can't be good with all the chemicals in the water. I think that it just moves the fish out for a while because I haven't see any fish kill from the process. I also know that the FWC would not allow anything that would be detrimental to the fish to go on.
The reason I am writing about the spraying was because when I was out fishing the other day, I saw that all the pad fields were brown and wilting. This told me that they had been sprayed to kill them back. From Astor to Lake George there were dying weeds and pads on both sides of the river. From what it looked like they sprayed the weeds and pads in the shallower areas and left the outside pads alone because they were still green and not falling over. You could tell it wasn't that recent they sprayed because of how brown the ones in the back were. So if you are fishing in this area there were some fish on the outside areas but fishing in the back was non existent.