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)."

Friday, May 3, 2013

Cryptomeria Scale Resurfaces in Ashe County

On September 1, 2010, I make the following post: Cryptomeria Scale Found in Ashe County. If you went to any of the meetings where I spoke at the following winter, you probably heard about this new scale problem. I've not really talked much about this scale since then and with good reason -- I've not seen it again.

After making this post in 2010, the grower cut down many trees and treated the rest. I couldn't find any live scale after treatment. Since then I've been back to that field several times and scouted in close-by field and never found any more Cryptomeria scale (CS) until today.

Cryptomeria scale (Aspidiotus cryptomeriae), like elongate hemlock scale (EHS), is another introduced pest from the Orient. It affects many conifers including hemlocks and firs. It causes serious and striking yellow mottling of the foliage and premature needle drop. On the trees we examined today, most of the damage was on the south side of the tree. A few trees were heavily damaged all over with scales even on the needles of the terminal. This is one scale you really don't have to hunt for to find. If it's there, you should see it.

Damage from Cryptomeria scale.
The scale has a very different appearance to EHS. The scales, especially the small immature ones, are round, and they line up in two rows along the backside of the needle on either side of the midrib. They look like fried eggs with a yellow center. The 'white of the egg' is actually where the scale has pushed up the waxy covering of the needle. Older scales are more indistinct.

These younger scales look like they might have been killed, perhaps from a fall
insecticide treatment.
Crawlers will start to appear in another month or so.
The life cycle of CS is similar to EHS. It has two generations per year and is most active in the summer months. It seems to spread very quickly and cause damage very quickly. However, it is much easier to control than EHS.

The scale is spread through crawlers and on infested plant material. This scale was found in three adjacent fields owned by different growers. Next week, we hope to scout other farms in the area to see how far the scale has spread.

Typically when I've found CS, I've also seen the twice-stabbed lady beetle. We didn't find any today. Perhaps it's still too early in the year for this helpful predator.

The grower in 2010 treated in early September and got excellent control. We didn't see any crawlers today, and so it's probably a bit too early to treat -- especially since we are having such a cold, wet spring that's keeping everything from getting active. But we'll definitely be following control from any grower treatments and pass results on.