The Value of Christmas Trees

"...there is no reason why the joy associated with the Christmas evergreen may not be a means of arousing in the minds of children an appreciation of the beauty and usefulness of trees; and keen appreciation of the beauty and usefulness of trees is a long stop toward the will to plant and care for them (Arthur Sowder, US Forest Service, 1949)."

Monday, June 21, 2010

Cryptomeria Scale

Cryptomeria scale (Aspidiotus cryptomeriae) has been a problem on Christmas trees for several years in Pennsylvania and other states, but not in NC until now. Alan Durden found some on Fraser fir in Macon County, which I had the opportunity to visit last week.

The trees were from 4 to close to 12 foot tall, not far out of Franklin. There was a very heavy incidence, but many of the scales didn't look healthy. Some had fungi growing on them. Others appeared to have been feed upon.

For those of you familiar with elongate hemlock scale, the life cycles and control of these two scales are quite similar. The biggest difference is that the cryptomeria scale is more rounded in shape. We found nymphs on the new growth on some of the trees.

We also found a lot of the twice-stabbed lady beetles (genus Chilocorus) -- both adults and nymphs. Richard Cowles and others reports that these are good predators for scales. I have never seen them feeding on elongate hemlock scale, and in fact usually only see about one a year, but there were dozens on these trees.

Because of the predators and because the grower only has a few trees, we decided to wait a month before deciding what to do for control.

Symptoms on the top of the foliage are similar to elongate hemlock scale. They aren't found on all the infested trees just like with EHS. I didn't see any of the white fluff that gets on trees with EHS. That probably doesn't occur.

This is what the scale looks like under the foliage. For a clearer picture, google the scale.

Here is one of the lady beetles. They are real pretty.

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