Can't think of anything that is constructive!
A lot of your employees are undervalued. Unfortunately the ones that ARE valued are generally worthless! That could definitely be a reason why employees feel undervalued! Can't compensate for incompetence!
Treating each other with respect for starters! It's the lack of qualified supervisors that continue to allow employees to disrespect one another. Because they're no better than the ones berating each other!
It's all about your leadership and training! People DO NOT have confidence in unqualified supervision. Being proactive and making timily decisions is the key to success. Untrained and unqualified supervisors is a recipe for disaster and that is exactly what's happening in your plants!