Before you get to that spot get her feet moving in different directions. Sidepassing, turns around numerous trees or rocks, stopping, backing but not in the direction of home. Keeping her feet busy will keep her mind on you. Bend her in tight circles, whatever you can think up but don't just travel straight ahead. That spot is likely her limit as to how far she will go from the barn. As you ride move her hindquarters over, both ways. As long as one hind is stepping under her belly in front of the other she can't rear. In order to rear she has to brace both her hind legs and rock back. You will feel her body thicken. If your gut tells you to dismount then do so and walk her past "the spot". It's not cowardice, it's smart. If you are expecting her to do something, she will. If you are a bit nervous she will sense that and behave accordingly because she's lost your leadership.