Variegated Holly Leaf Drop
My variegated Holly is losing leaves rapidly in one section. The disease appears to be contagious. It involves the blackening of the tip of the leaves, followed by it dropping off. I have included a picture of the affected area. We are after the wettest December on record. This seems to have prompted it. Please help me save this tree. I 100% don't want to lose it.
The excess water and lack of air circulation are likely the issues that have left your Holly with a fungus disease.
Clean up and destroy all dead material lying on the ground around the plant to help prevent further issues.
Spray the plant with a fungicide, follow application directions on the packaging.
You will likely need to reapply until the plant has made a recovery.
Here are some links to help you.