How many times have you been riding along a beautiful trail in the mountains and everyone on the ride is on the other side of that "@#$%^&* blankity blank @#$#%$# CREEK" and your horse won't even get close enough to get a good look at it.
I have a couple of methods that just might be helpful to you,

1.Teach the horse a specific cue that means Go Forward.

2.Use the "V" exercise.

The following procedure will help you teach the Go Forward cue.  This procedure will teach your horse a cue to go forward under ANY situation.
 
1. First kiss to the horse and if he moves forward, pet him.  Do not use your legs yet.

2.When you kiss to him and he does not move, kiss again, and again, then start bumping him with your legs.  You will have a tendency to start out bumping him hard. Resist the urge.   Think about bumping him at a rate that you can keep up for an hour or more, until he does move.  It is important to continue cueing until the horse takes one step forward. When he does, stop bumping and pet him.   If the horse does not have a specific leg cue to go forward this process may take several days of concentrated teaching to get the horse to respond correctly every time you cue him.   The KISS is actually a pre-cue and the bump with your legs is the GO FORWARD cue. Always start with the simplest, lightest cue and increase the pressure to support it.  The horse will get the idea and move his feet when you squeeze or start to bump him. 

3. Remember to pet your horse after each time he responds to your cue.  This feels good to the horse and will speed up the learning process.  When you reward your horse with the pet, use a rub instead of a pat, or slap on the neck. The horse's skin is about 7 times more sensitive than humans.

4.This is all done away from the fearful object and may take several days of repetition, concentrating on this cue alone to get it completely learned by the horse.