When I ride, I ignore scary things.
I am a huge fan of approach and retreat in the right circumstances (trailer loading!), but sometimes (like at a show!) it's not practical. So my horses are trained to trust me, and think about me, when I'm on their back.
When I find a scary area (like the side of the arena near the road with the cars), I work there exclusively. Every day. And we do circles and a LOT of bending and stopping and backing and when they flip out (which they will) you just stay calm, and continue to ask them to do whatever it was that you were doing. If you were circling and asking for a shoulder in, you just CALMLY and PATIENTLY continue to ask until she does it. The horse will soon learn to pay attention to YOU. This is why horses are 'spooky', or why they get silly under saddle. Because they're not putting all of their attention on you.
Another thing I do is use that area as the rest area. When my horse is tired and huffing, I'll take him to the scary area and ask him to stop. They learn REAL quick that this is a good place!
I like desensitizing (which is approach and retreat), but I think all the desensitizing in the world doesn't do a thing if the horse doesn't learn to pay attention to you at ALL times and trust you to take care of them. I don't care if my horses are scared of cars when I'm off of them as long as they're as docile as a lamb when I'm on them. (funny thing is, when YOU stop caring about scary things... so do they. lol!) They learn to trust me, and to look to me for their safety. You can desensitize her to the woods all you want--and when you go to a different show, with different woods, she'll be scared all over again.
Which is why I teach my horses to be confident--in ME. ;)