I plan to do exactly what you describe but it is too early for me to plant pole beans of the P vulgaris type. However, we did plant peas right on top of the fall pole beans and that worked great (I posted a couple pictures on the other pea thread, but those are in zone 10). Both the beans and peas were healthy though. Now, are you sure you have a 'disease' or is it just the natural life cycle of the peas? which zone 9 are you in? they do not like heat at all, have you had a bit of a hot spell? then browning leaves would be normal, no disease to worry about. Maybe someone else has experience in our zones and can give us advice. I have cool springs and hellishly hot autumns (usually) so I'll be planting beans later.

I'm in S. Louisiana and thought about the fact that they may just be at the end of their life. I planted them in Nov and we had some heat in the last 2 weeks.

But, I guess my real question is "do the same diseases that affect peas affect pole beans"? Because if they do, then rotating would be better than planting in the same spot.