Just spent the last 3 or more weeks spraying ALG for a farmer friend of ours. Didn’t look that bad until I started! It was relentless! Spot spraying ended up being a waste of time so, we ended up with a small boom sprayer on the back of a UTV, which worked a treat. The larger patches were sprayed with the small boom, the rest were spot sprayed from the UTV. Several hundred acres have been successfully sprayed, and with a follow-up in the Spring season we should be on top of it for a while.
The problem with ALG is, you leave it for a year, thinking it is all ok, and it comes back with vengeance. Not a good year for the stuff! But in the end, a good ALG, is a dead ALG! Keep spraying!