Q.Why is one of our Sky pencil Japanese holly dead and another planted the same time is fine.
Our shrubs are in their fourth summer. Very suddenly one of our sky pencil Japanese holly shrubs has died. The other one planted a few feet away looks fine. Do they have a short life span? I cut back the height about twice a year to keep them about four feet tall. We live in Louisiana.
This plant has some vulnerabilities, including root rot from poorly drained soil and/or overwatering, and fungal disease.
Your frequent pruning is opening wounds that can become contaminated from pruning tools or infection from airborne fungal spores. Disinfect your shears with Lysol spray or 10% bleach solution before each pruning of the remaining plant. Spray with neem oil or a biological fungicide immediately after pruning.
The soil and drainage may be different in the two locations, or if not, the remaining plant may be vulnerable to the same fate if the soil is in fact heavy clay and poorly drained.