Why are my arborvitae dying in the center of a long row on sloping ground? A local nursery says there is no evidence of bug infestations based on a tree sample I brought to them. About 10 adjoining trees have died, 23 others are thriving. A neighbor says the previous owner of my home replanted those same trees twice after they died.
Clark County Washington
Thank you for your question. There are a host of problems that can befall arborvitae, which are described here: http://hortsense.cahnrs.wsu.edu/Search/SearchByAlphaPlantName.aspx?letter=A&PlantDefId=2 Without photos of the branches and leaves, it is difficult to diagnose which one(s) of those are the issue, or whether there is an abiotic (environmental) issue, such as pooling water or a soil pathogen. If it is one or more of those, replanting the same plants time after time will typically get the same result: dead plants. I suggest you take some tissue samples to your Extension office for examination. They may also suggest a soil test. Here is their contact information: https://extension.wsu.edu/clark/ Good luck!