You can get pics of landscapes, but try to find something with contrast to use as your focal point. Sometimes manual focus is your best ally when trying to focus on a scene with little contrast.
Here are a few landscape shots with a lot of trees, but I did manage to find something to use as a focal point. Sometimes you can find something in the foreground of the scene to focus on, but that requires you to close down the aperture.
Here's a road that's near my house and I shot this through the windshield. I focused on the road.
Canon 30D - Canon 70-200 f/2.8 - 1/100s f/2.8 at 70.0mm iso250 (this would have been better if I could have closed the aperture, but since I was driving, I didn't want to shoot below 1/100s).
This is a shot taken at Memphis Botanic Gardens
Canon 30D - Canon 35L - 1/320s f/5.0 at 35.0mm iso200
The focal point is pretty clear in this shot that I took at the farm.
Canon 30D - Canon 100-400L - 1/800s f/5.6 at 400.0mm iso400
Connie, I chose these images because they were all shot with an aperture of f/8 or faster. You should be able to get your landscape shots without any problem. Try manually focusing a few times just so you'll be familiar with it when you need it.