Steve,

I think my original post mentioned that the wing stalls first at the
root and then move spanwise toward the tips, and that stall fences
delayed the seperation from moving out towards the wingtips and hence
the ailerons. A more common way to ensure the root stalls first is
washing out the wing. Of course this doesn't apply to swept, tapered,
or elliptical wings which either stall uniformly or at the tips first.
Dave