Black bamboo bending over

I have black bamboo (Phyllostachys nigra) "trees" in my backyard garden in Surrey. They are approximately 20-25 ft tall. In the last rainy one week or so two of them have flopped low, with their top now touching the ground (as seen in the pictures). I would appreciate any advice as to what I can do or should do with those two "trees". Is it possible to straighten them back up? If I prune them will they stand up again? How should I prune them? Finally, what should I do to other bamboo "trees" to prevent this from happening?

Thank you in advance.

Ajay

 

If the culms are bent and not broken, they can be straightened by simply lifting them up and then supporting them in an upright position. It may be difficult to find an adequate support if they are actually 20 ft tall or taller, but what may work is to wrap a sturdy wire or cable around the whole clump of bamboo so that the upright culms will support the the ones that have a tendency to lean over. You may need several turns of wire to provide sufficient support. I've been doing that for some time with P. aurea to prevent wet snow from bending and breaking the culms.