Pilot reported an NMAC event during landing with a non-reporting opposite direction aircraft. Pilot took evasive action to avoid a collision.

Narrative

I was in the traffic pattern at ZZZ airport; and was established in the right downwind. Was making position reports and knew there were two planes; one reporting 4nm to the south and one reporting 9nm to the south both coming in on final; both of which I had on my GPS unit. I had determined that I could make it in before them; so I started my descent and started turning base. At that time; I saw an aircraft perhaps making an opposite base turn to final at approximately the same altitude maybe 500-1000ft away; which I determined to be a problem and I went around. This plane; which happened to be an ag plane who didn't call any position reports up to that point; Aircraft Y. If he would have called up any position reports; I would have been able to see and avoid him better and it wouldn't have become as much as a problem as it was. He has caused an issue before (this is the second time; last time last year) and if he would make position reports; that would solve a lot of problems. I know he has a radio because he has used it before; he just needs to use it and not cut so close behind especially since I was established in the traffic pattern and had been for some time and there were others.