Friday, May 5, 2017

Forensic Gardening

Remember earlier this spring I showed the American holly that had lost almost all its bark -- I thought the cause was sunscald from our hot February followed by a brief cold snap this winter.

Post: My Ilex opaca won't survive

But even as I came up with that theory it didn't seem right. It just wasn't that cold for that long after the warm spell in February.

Chris from Bartlett was here today and he looked at it and said "this tree lost its bark the winter before -- in 2015-2016 when we had such a harsh season, with subzero temperatures for weeks on end."

The injury occurred because Ilex opaca, at least when first transplanted, is cold susceptible in zone 5. And that winter two years ago was brutal.

There are mature, beautiful Ilex opaca trees in Connecticut -- they do grow well here although it's the northern end of their range. But they have to experience several mild winters when young in order to go on to live happily when older. Then they can take a brutally cold winter once fully established. But not the first years after transplant.

The brown edge is scar tissue that
grew last summer to seal the wound
The way Chris knew it was damage from a prior season is that the little strip of remaining bark had formed a tight callus to seal the wound. That could not have occurred yet this spring, it's way too early for any bark growth.

That scar tissue grew around the edges last summer, so the damage was there from the winter before that. The loose, dead bark had stayed wrapped around the tree last year so I never noticed it had come unattached. Now, this season, it disintegrated and fell off, exposing how extensive the dead area is.

Forensic garden analysis -- it's one of the real fascinations of gardening. I now have a cause for the holly's impending death, and a timeline reconstruction of how it happened. But I still don't know why it had to happen.

Why did my American holly have to spend one of its first young years after transplant in winter's iciest clutches? Why couldn't its first winters here have all been mild ones, like this past winter?

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