Emerald Green Arborvitae

What's going on here? As far as evergreen trees used for home landscaping go the Emerald Green Arborvitae is about as nice as they get. Topping out at approximately 12 feet tall the bright evergreen tree needs very little trimming. it looks and stays neat whether used as a specimen or in a hedge. We have used it ourselves in a hedge, as the "cornerstone" of a display garden and as accent groupings (usually three to a group). This spring we were greeted with this new look.

One out of the three evergreen trees (Emerald Greens) planted side by side in this group was dead. Top to bottom completely brown. It can be difficult sometimes to fiqure out what happened to an evergreen that just appears to turn brown overnight. But chances are it didn't just happen overnight. As evidenced by Christmas wreaths evergreen foliage can stay green for many months even after having been separated suffered the damage months before it actually turns brown. This is often seen on newly purchased & planted evergreen trees. Several weeks after planting you may noticed branches that have turned brown. Closer inspection will usually show that the brown branch is actually broken. This could have happened while the tree was being dug, B&B'd, transported and or replanted. This kind of damage can be trimmed off. In most cases new growth will quickly fill in the trimmed areas.
But this is different this evergreen tree has been planted in this location for about 10 years so it's not a handling issue. Besides it's not just a branch or two but the entire tree, no longer an evergreen it is now an everbrown. There is no point to attempt to save this evergreen tree. It is far too gone to ever recover.
According to Ron Smith, Horticulturist, NDSU Extension service @ http://www.ext.nodak.edu/extnews/hortiscope/tree/cedar.html
"Generally plants that turn completely brown are being hit from the roots through anaerobic conditions, a change in the water table, or a root rot organism is spreading through root grafting." Since Emerald Green Arborvitae are self rooted it would seem the first suggested reason to be the most likely. Water & or ice can easily accumulate at root level in winter. As an example lets say the ground is frozen, it warms to just above freezing as a storm comes through. Since the air temp is warm it rains instead of snows. but the ground is frozen so the rain sits and freezes right at root level. This can easily halt the evergreen trees process of taking up water. If the sun comes out while the roots are still frozen in ice the tree will not be able to send water to the foliage.
A second possiblity for this evergreen tree to have turned brown might be an insect like a borer. This should be apparent when an inspection is made of the everbrown tree. A borer especially would leave noticable evidence like little round holes bored into the tree trunk. The roots can also be inspected for evidence of bugs or rotting.

  Either way, water starvation or insects, how is it that only one of three evergreen trees in the same location bit the dust ?
  This phenomonon is repeated over and over throughout North Eastern Maine in spring 2009. Emerald Green Arborvitae side by side with one evergreen tree gone the others still green and growing.
Don checked our brown Emerald Green finding no borers or insect damage, leading me to believe water + winter was the culprit in this situation.