Tallest pole bean varieties

Does anyone have suggestions for pole beans that grow vigorously to 20' or more and which are productive producers of decent dried beans?

I'm thinking it would be great to send twine over the forest edge tree's branches and send pole beans up the lines.  Seems possible to produce a lot of beans with little land use, but not sure if there are any good candidates or if crossing and selection might be needed.

All suggestions appreciated.  If you have some seeds of the one in this picture I'll trade for a cow!

Here's an article on a heritage bean that grows to 20' and can be used for dried bean production.  They call it the Pezel pole bean and it grows on Vancouver Island.  I haven't been able to find any source for it  Anyone know of this lovely bean and have a lead on where one could get it?  It sounds so wonderful!

Back in the '80's I happened to rent a patch of land, no more than an acre, from a neighbor that had historically been their camper trailer parking spot next to a small river, pretty protected surrounded by big maples, called it their summer home. Wife had to go to assisted and the land became available. First a layer of manure, chix & goat, thick at least twice the normal rate by spreader. It being sod, I pulled one of the shares off a double set of plows so I could go deep, and root prune the edges, i got the frame almost on the ground while turning and it was all a 60 hp 4x4 deere could handle, let the ground rest for a couple of weeks, went back and put a minimum of a foot layer of compost turned under with a tiller run north/south and the east/west.    I planted a variety of pole bean called Northeaster, I still go with this variety every year, our own saved seed.  Planted 2 100 foot rows,  running North/South10 feet apart on 8 foot t posts on 9 ga annealed wire, top and bottom, strung with baling twine every 4 in to run up, use this set-up still. Panted back row 1st waited 2 weeks and then front.  Those beans came in so thick and strong I was picking 10 - 12 5 gal pails every other day. The vines ran up the trellis and showed no sign of slowing so I put 12 ga wire on an x pattern post to post over head, the beans filled in the canopy and we go up to 18 pails a picking, sold tons off the stand, neighbors and family got sick of getting bags of beans.  
 The point(s) of this ramble is you'll have to 1. go deep to the root zone to cut off competition from the trees, 2. fertilize to excess and mix in very well. 3.  if you trellis to 20' you'll have to get  up there to pick, up and down, up and down will get old quick.
The variety usually runs 8-10 ft but yearly evidence points to the limits of condition/fertility governs the growth limits, plan accordingly, see to the end of the plan

We planted Kentucky Wonder and Blue Lakes pole beans. Both varieties would have probably grown to 20 feet if our trellis was that high.

Wow Steve....wow!!!  Thank you.  Did a little follow up reading and it sounds like Kentucky Wonder has seeds that are good baked beans.  I'll try experimenting with both, though.

Scott, thank you for sharing that.  I completely agree on the harvest being a lot easier on the ground for a lot of string bean picking.  I should clarify that I'm wanting to shoot pole beans high up lines for varieties that make great dry beans.  I'm hoping to just drop the lines in the fall and harvest all the dry bean seeds for baking, soups, etc.

I grow Blue Lake pole beans to 12' even in our very short season. We only harvest them as late season green beans (fabulous - a favourite!) but in a milder climate I'm sure they would grow even taller and be more productive. I have no idea what the mature beans would taste like.