I seldom allow plants to die standing. As soon as the plants are showing sign of old age, or serious pest attack, I will put emotion aside and pull out the plants. Our winged beans are showing every sign of getting old. Leaves getting smaller, beans start to emerge in awkward shapes and pests seem to hover around for a big kill.
I pull the plants out and dismantle trellie.... and thats the last of our winged beans.