I noticed little brown acorn like things growing on my emerald green arbovitae trees. What are they? and are they harmful? Should they be removed? In addition I had 12-14 foot trees planted in my backyard which lasted 2 seasons and now they are turning brown and the brown seems to be spreading. At least half of my 30 trees have died and there is no consistent pattern. There could be one healthy, two dead, two healthy three dead. What can I do to prevent the rest of them from dying? I live in New York.

These are the seed structures associated with Arborvitae and are a normal part of the plant and removal is not necessary. At least here in the Midwest arborvitae have suffered regardless of age and being recently transplanted. Older Arborvitae suffer from long term stress from extremes in seasonal conditions impacting the root systems. Newly transplanted ones have suffered as they attempt to establish in the new locations. Transplants typically have a much reduced root system and depending on size can take 3 or more years to recover. Care during this period requires continued attention to water during periods of dry weather and good. A reasonable rule of thumb is a year of recovery for every inch of trunk diameter. poor soils, poor siting can mean even longer.