I have a ton of small diameter black locusts popping up off a runner and was thinking of cutting a few to use as bean poles. Are the natural insecticides/fungicides in locustwood going to affect the plant growing on them or will I be fine?
Could you just leave the plant (or thin out) and plant beans next to it and run them up a living bean pole? You would be increasing your n-fixation, so much so that you could add another plant and be fine nitrogen-wise. I don't thing you should worry about fungicides in black locust, that's mostly a problem with getting it to decompose. Young plants don't have much of the fungicide anyway, since they break down easily.