My horses come to a specific whistle. I started every time I fed I would whistle this little tune to let them know I was coming, now I can use the tune any time and they all come to see if they might get fed. I see nothing wrong with treating them for coming either, a little positive reinforcement can be very useful.
If I have time to kill, I walk her down. If I'm walking straight toward her, she has a tendencyo to dart to one side, so I also side-step in that direction to cut her off. I'll raise my hands if she's close and she'll either stop and let me catch her, or she'll double back and dart the other way. Sometimes, this game continues on for 20+ minutes, but most times, she usually gives up within a 5 minutes. As soon as I catch and halter her, I scratch and rub her in the places she loves the most. Some days, I'll go out there without a single intention to do anything with her. I'll catch her, scratch her and turn her loose. That way, she won't learn to associate me with just work. Other times, I'll catch her and we'll go for a walk. Again, she learns that I don't just catch her to make her work.
Whatever you do, never start the walking down process and quit. That just teaches them that they won't have to work if they can avoid you and it'll be even harder to catch them the next time.
This is what I've done with my girls! I live in the middle of National forest (no people). On nice days we will often let our horses loose on the property to graze and stretch out their legs. When we started this -my horses were a bit hard to catch. They're like "WOO HOO!! WE'RE LOOSE!!!
NEE NER NEE NER NEEEEE NER!!!
" Running around, dodging you from catching them.
What I began doing is before they even saw the treat I would start to whistle. I'd whistle for a 10-15 seconds. Then I would shake the treat bucket. When they'd come running I'd let them have their treats. While they were eating their treats, I would continue to whistle and praise them up BIG TIME! An "atta girl!", a quick rub and then I'd leave them be to run around again. It wasn't before long before I'd whistle and BAM! Heads would shoot up, they'd give me that "REALLY?!
" look and they coming running at a gallop. Make sure they RESPECT YOUR SPACE! At all times! You don't want them charging up and plowing you over for that bucket. Now when my girls come running I hold up an extended open hand and say "Easy!" At about 20 ft. away they slow to a trot, then the last few feet they approach me at a gentle walk. It's great, they will stray quite a ways away now grazing (I can't see or hear them anywhere). I let out a few loud whistles (my dad taught me how) and in few minutes they'll come rolling into the yard full steam ahead! **As said before, start with a short distance and then increase the distance.
It sounds like there may be other horses in the pasture too with your horse. This will make it hard to just teach your horse to come. I would start in an arena or pen just the two of you and work on the re-call. Then hopefully it will carry over to the pasture. Also walking up and putting the halter on, loving on them, then letting them go is a great thing too. I had to do this quite a bit with my horses because with being 100% they were very sketchy about you walking up to them for fear you were gonna catch them and throw them back in the coral!
Good luck! :)