Good answer iride. I had the same exact same problem with my horse...but its gotten a lot better. I tried the sending him away thing too, but I tried it in to large of a pasture and ended up teaching him that he is way faster than me and that it was really fun to show me everytime I came out with halter and lead rope lol. I really found that it was a combination of things that really improved the situation for me. The first thing...like iride said...is carry your halter and lead rope with you all the time....especially when you are bringing treats and feeding. Also...and I don't know if this applys to you...but when I went in the pasture to get him, I used to approach him in a cautious way (knowing he was going to walk off) and when I go in to feed or for something else its always with purpose (the opposite of cautious). It helped me tremendously once I realized what I was doing. If your body language looks like your up to something...your horse is going to know it. I personally love to give Major treats too...but only after he's caught. When I first started out though...I had to leave the halter on him and I would kind of bribe him with the treat....then once I had him by the halter, I gave him the treat. I know a lot of people are against the whole bribery thing...but for me, it was the most effective tool to catch him so that I could teach him to trust me without the bribery. I did have to do a little experimenting with the treats....Major wasnt crazy about the carrots I first tried....but he loves apples. I personally don't think it matters wich method you use as long as you find what works for you and your horse. I think the key is that you train them to be caught just like you would train them for anything else. Be willing to spend the time it takes to really train them. It took me a long time to get that in my head and so it was really really difficult for me. I'm sorry for the long winded post...but catching Major for me in the begining was soooo difficult and so I have learned a lot. I actually got to the point that I dreaded even going to the pasture at all because he was so difficult about being caught. I love to go now!!!! Hope this helps!!!!!
One last thought too lol. If you go to catch him.....make sure you do...even if it takes all day. Everytime you try and don't catch your horse...the next time you try it will be a little harder