Is there a way to turn off pinch/zoom for the desktop only?

Looking at System Preferences>Trackpad there are no options to customize this feature.

I'd install Better Touch Tool (free). Add two gestures for Finder ONLY that have "No action" associated with them. This disbales pinch/zoom on the desktop AND in any Finder window, but not in any other application.

If you'd like to occasionally use pinch to zoom in the Finder (to zoom into a photo thumbnail for example), then add two more gestures, again for Finder ONLY - but this time also selecting one of the modifier keys (e.g. "Option" key). For these gestures set as "Use Apple Default or do nothing".

Together, this enables disabling of the zoom feature (to prevent accidental zooming of the desktop icons for example). But whenever you'd like to zoom into a document or photo etc in a Finder Window (which are also now disabled), you can now simply hold down "Option" key and the Pinch functions work again.

This solution works for me on 10.6.8

Do you realize that the original post is 1 1/2 years old?

Yes, I am well aware of the age of the thread. What difference does the age of the post make? People (such as myself at least) use Google to search for answers. This thread is one of the hits (among many others that were locked/archived due to age). I then posted my solution for others to find and read/use if they wish. Is that so hard a concept to grasp?

I just found your post and it was extremely helpful. Thank you, ZX48!

Ditto OgamDigital - my thanks to ZX48!