In organizational work, the lack of trust has the same "oxidizing" effect that rust has on metal. Little by little, day by day, inch by inch, the look and feel and effectiveness of the organization is compromised by that lack of trust. Without the "T," we are left with "rust."
Both in the care and maintenance of metal and in the care of maintenance of organizations, simple attention and a little preventive maintenance are all it takes to keep "rust" at bay. It's really not that hard, and the benefits of that attentive/preventive maintenance are immense.
When trust is absent, "rust" remains.