Dirtmechanic
Garden Addicted
Would you consider pine bark mulch under the beans to be worth the trouble?Yes. I grow peppers under cages covered with spun polyester row cover to exclude pollinators, then open the downwind side to allow insect predators, leaving the top & 3 sides covered all season. The peppers really thrive under the light covers, greatly out-producing those grown in the open. I'll try to post a photo of how those peppers look now (but not on this thread).
I cover young squash plants with floating row cover too (to protect from SVB and usually the first squash bug hatch) and they too thrive under cover. If I spaced bush squash more widely, I could even have total control of pollination, and I'm sure the squash would be fine... but that would only be practical for winter squash. I can't imagine hand-pollinating zucchini all summer.
I've tried covering bush beans & tomatoes too; but the increased humidity & reduced air flow caused severe foliar disease. When the cover was removed, the plants recovered... as in getting healthier, not pulling the cover back on. For me, covering them would not be worth the trouble anyway, since both plants tend to get stronger on their own with time.
IMO for beans, it is more important to cover the ground beneath them - to prevent mud splash, and keep the roots cool & moist - than to cover them from above.