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, August 19, 2011

Clingman's Dome and Wild Trees

Ghostly skeletons of Frasers emerge in the fog on Clingman's Dome as young trees grow around.
I had the opportunity to visit Clingman's Dome in the Great Smoky Mountains National Park this week. It had been years since I'd been there. The last time I visited, it was with Kristine Johnson with the National Park when they were treating for balsam woolly adelgid (BWA). At that time, they used insecticidal soap in the summer to treat the trees around the parking lot, walkway and tower on top of the mountain. To my knowledge, these treatments have stopped.

Treating on Clingman's Dome for BWA in early 90s with insecticidal soap.
The soap was mixed in the white vat and a powerful pump was used to spray the product on the trees.
They would spray the trees with fire hoses using many volunteers.
Hard hats were required as the pressure spray might bring down limbs.
Insecticidal soap isn't the best treatment in the summer as there are eggs present, and many survive the treatment. With soap there are no residuals to kill the crawlers that emerge from the eggs, and it takes about a month for the eggs to hatch. However in the winter when eggs aren't present the road to the top is closed. Also I'm sure there was quite a bit of damage to the natural habitat just from all the spray activity.

Today it looked different than I remembered. There weren't many tall Frasers, but there was quite a bit of healthy regrowth. Still, it looked like there was a lot more open ground than when I was there last.

Shot from the visitor center parking lot at Clingman's Dome on 8/17/11. 
We were there on a very foggy day as can be seen in this video. It is living in the fog that makes Fraser fir such a great Christmas tree. Frasers are very sensitive to dry air since they live in the clouds. They quickly shut their stomates which keep them from drying out.

The following are photographs from the visit.

The tower today. 
Lots of wildflowers are growing in areas left bare from dead trees.

The young trees coming on look good, but they are somewhat resistant to BWA as they produce juvabione.
This is an insect growth regulator that keeps the insect from becoming mature.
Larger trees stop producing juvabione and become infested.
Each white spot covers an adult female which will lay a dozen eggs or so. 
The tree in the previous picture is on the left. It has no top left. Other trees around it still do.
The loss of apical dominance is a symptom of BWA infestation.
Even with the dying trees, Clingman's Dome is a popular destination.
The steep walk to the tower and all the fog doesn't keep people from going to the top,
even if you have to stop to catch your breath along the way!

Monday, August 15, 2011

Cinara Aphids

Cinara aphids are some of the largest aphids in the world.
I can't believe I've never had a post just on Cinara aphids! Now is the time the people are starting to think about them. I talked to 2 or 3 growers last week who asked the same question -- is it too early to treat for Cinara aphids and keep them out of my go-to-market trees? Sadly, there isn't an easy answer to that question.

I talked with only one grower so far that has seen Cinaras in his trees this fall. Mostly they aren't seen until they show up in someone's home. Many people now treat preventatively for the pests, using Talstar or Wisdom which are both bifenthrin products in late September or October. But now is still a good time to treat for elongate hemlock scales with Asana and Dimethoate. And if you know Cinaras are in your trees now, should you wait until October or go ahead and spray?

The question that we don't have an answer to is how quickly do these aphids move into new areas. Some individual aphids have wings, allowing them to fly into trees. However, they aren't very good fliers. Basically all they can do is get up in the air and allow the wind to carry them places. They don't direct their flight like a fly or a bee.

A winged individual. 
Once they are in suitable locations, they lay live young, so their numbers can quickly rebound. However, most of the pesticides that people are using will last several weeks on trees. Therefore it would seem unlikely for Cinaras to move into trees treated in mid-August by mid-November, though the possibility exists. It would depend on each grower's concerns about the pest and how they are applying their materials. Spraying with a mistblower may allow quicker build-up again, while using a high pressure sprayer and getting good coverage will more likely take care of the problem from now until harvest.

One reason to go ahead and treat now is that most of the aphids are still higher up in the tree where they are more easily controlled. As it gets colder, it seems that the aphids move to the lower branches, making it harder to get a chemical to them, and certainly with a mistblower.

When Cinara aphids are on the trunk of the tree, it is harder for a mistblower to reach them.
No matter if you treat now or wait, there is a new product on the market for pest control in Christmas trees including Cinara aphids. Sniper, which is a 25% bifenthrin product, is now labeled for Christmas trees. It should be cheaper than Talstar. Click here for the label and msds sheets.

And what about the Cinara eggs? I've only seen them once in all my nearly 23 years working in the industry!

Cinara aphid eggs found in Ashe County about 10 years ago.
In the literature, different Cinara species only lay eggs infrequently. So basically, growers are fighting a live aphid that can reproduce very quickly. And if anyone does see these eggs, please give me a call. I'd love to see them again!

Whenever you are in your trees this fall, be sure to look closer if wasps or yellow jackets are interested in your trees. It could well be Cinara aphids. This typically happens during warm, dry days in the fall when the wasps are especially active. Beat the foliage of a few of these trees to see if aphids fall out.

Wasps are attracted to the sweet honey dew that aphids secrete.
You sometimes find Cinaras when you are beating the foliage to find other pests.
Also be sure that the folks tagging and harvesting your trees can recognize the aphids and their characteristic purple smear.

If you do end up with problems with Cinara aphids on harvested trees, remember these links for information. If you have a retail-lot, you might want to make a few printed copies of the last link in case of problems.

I am always happy to speak with your customers about this pest problem should the need arise.

Thursday, August 11, 2011

Organic Project Update

Last month I visited the Extension Organic demonstration and once again rated the trees based on their terminal growth and overall appearance. I made a similar ratings last year and posted them on my blog on August 24, 2010

I rated the tree appearance the same way I did last year. Trees were given a rating of "1" if they were barely growing. A "2" rating was given to a tree that was growing better, but still had poor color and bud set. A "3" rating was given to a tree that was growing acceptably. A "4" rating was given to an exception tree both in color, bud set, needle length and fullness. Of course these ratings were completely subjective and sometimes I had trouble deciding between a "2" and a "3" or a "3" and a "4."

Here are the results:

The results were very similar to last year. Some trees looked worse than they did last year and some looked better. Overall the organic trees appeared to have improved a bit, but there were still many more trees growing poorly than the "late" organic trees. (Remember that the "late" organic trees will switch to complete organic practices next year, but so far have been treated conventionally with Round-up and synthetic fertilizers). 

But as they say, pictures are worth a thousand words. Here are two shots in July of the organic and late organic trees:

Organic trees -- there are a few good trees but not many.
These trees have been grown conventionally and will switch to organic production next year.
It will be interesting to see switching to organic fertilizers will affect the "late" organic trees. I'll let you know same time next year!