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)."

Tuesday, November 8, 2011

How Well Do Scale Infested Trees Hold Their Needles?

If a tree is infested with scales, will it cause the needles to shed prematurely? Last year I looked quite a bit at this issue, but without a lot of success. Here are links to the previous posts in case you are interested in following this story: 1. Setting up the study; 2. The results. The big problem with last year's study was that the room where I kept the shoots got way too hot, and there were many branches where the needles shattered. This isn't how Fraser fir normally behaves when cut.

So this year I'm trying again. Yesterday Jeff Vance helped me  collect some scale infested branches. I will be comparing needle shed on these to branches from uninfested trees in the same field. We also collected some heavily infested branches from a second field just to see if they fared worse.

I will be monitoring needle shed on this year and last year's growth. Each branch is in its own water container, with the 3-year-old wood in the water. The study is set up at my house so I can keep an eye on them better. I noticed this morning that they are already taking up water!

Small studies like this allow us to look at this issue with a great deal of detail under controlled conditions. But I'm also very interested in hearing your observations. Are you finding that needles shed worse in scale infested trees? If you have any observations, please let me know. Some questions I would like to ask are these:

  • Were the trees heavily or lightly infested? 
  • Are you selling trees in northern or southern markets?
  • Do you see a difference in performance between foliage in wreaths and trees?
Send me an email at: jill_sidebottom@ncsu.edu

As always, let's learn together as we try to live with this new pest.

Monday, October 31, 2011

White Pine Problems

People still have white pines! And this fall, these have been hammered in the northern mountains by what we think is a needle cast.

People started seeing yellowing and browning needles a few weeks ago. Damage typically occurred in the upper portion of the plant but occasionally was all over. Many growers commented that they had been in the field just a few weeks prior to this and saw no problems, even tagging some trees, only to come back later to find major needle loss.

When you look closely, not every needle in a fascicle is affected. Sometimes there are bands of green and yellow tissue on the needles. Many growers also found that only the sheared white pine was affected. We only found one site where there were some unsheared white pines that also had the same symptoms.

When this occurred in 2007, the problem was diagnosed as Bifusella linearus, a needle cast found on white pines. We have sent samples off to look at a positive identification this year. However, it is often hard to diagnose needle casts. There are several fungi associated with white pine needles. And there is also confusion between needle casts and ozone injury on white pine.

Ozone damages plants by making the stomates sluggish. It is typically the fast growing trees and weeds that are affected most by ozone. The USDA website (click here for site) lists the following plants as good indicators of ozone damage along with the damage seen:

  • Blackberry, secondary canes (Rabus spp.): Red to purple stipple.
  • Black cherry (Prunus serotina): Red to purple stipple, may drop the injured leaves early.
  • Common milkweed (Asclepias syriaca): Purple to black stipple, leaves may be chlorotic (yellow).
  • Yellow-poplar (Liriodendron tulipifera): Brown stipple, may drop the injured leaves early.
  • White ash (Fraxinus americana): Red to brown stipple. Similar injury is also found on green ash
So if you suspect ozone, look at these indicator plants nearby to see if there is also damage. White pines were taken off the indicator list in 1995. If these are not showing symptoms, it is most likely a needle cast.

This is also some question if fertility is playing a role. This time of year calcium deficiency is showing up in Fraser firs and white pines. If you are having extensive problems with needle loss, it might be a good idea to take some soil samples and plant tissue samples to further diagnose the problem.

No matter what is causing this damage, there is probably little a grower can do. One of the main reasons is that the profit margin is so low on white pines that it makes any fungicide treatment unattractive. However, when we get a positive diagnosis, I'll pass along treatment options.

Of course the main question is if the damage will continue to get worse this fall. In falls past it did not, so hopefully what we're seeing right now is the worst of it, and undamaged individuals will remain looking good. The following are some photos I took on Friday.

Banding on the needles

Not every tree is affected and not all the same way.

On this plant, damage only occurs in the upper portion of the plant.

Another shot of banding.

This tree was affected overall.

Thursday, October 6, 2011

Last Treatments

I haven't posted anything on my blog for quite awhile. Not because I haven't been busy, I just wanted to get all my results together before doing so. I've been evaluating multiple spring applications of Safari and other materials for elongate hemlock scale control. Since I feel like I should wait 4 months before making evaluations, it has taken quite awhile. I should finish with the spring applied stuff this week, and then I'll compile the results. Maybe I'll even have them by Friday!

However, I did want to let everyone know that I put out my last EHS treatment yesterday. Well, Jeff Vance did actually. We treated trees with Sniper, the new bifenthrin product and a dinotefuran product (active ingredient of Safari). We mixed the products to give the same as 10 oz Talstar per 100 gallons and 8 oz of Safari. Two rows of trees Jeff treated like a woolly spray, and two rows like a twig aphid spray. We used about 1/2 the water the second go round. Those results, I won't have until February!

If this fall treatment controls scales, it would fit in very nicely with production of Fraser fir. With it you would be controlling woollies, twigs, scales, spiders, and Cinaras in go-to-market trees. You have lovely fall weather which is usually drier and cooler (it seemed rather hot to me in that spray suit though!) to do it in. AND, you wouldn't be affecting the predators at all. So that means you won't be creating problems with rust mites come spring, or a resurgence of scales the following year.

What predators are most important for the control of scales? Lady bugs will feed on them, especially the twice-stabbed lady beetle, but also smaller ones. We've also seen lacewing larvae feeding on scales. There are also parasitic wasps that develop inside the scale itself.

I will share one observation I've been making. When people are using just Safari in the spring or summer and not adding a synthetic pyrethroid (esfenvalerate (Asana) or bifenthrin (Talstar, Wisdom, Sniper)) you see a lot more parasitized scales.

In fact, one day I poked open a scale that had a wasp still inside the scale, and when I gently teased it out, it moved it's head around.

Bugs are so cool!

Predatory wasp developing inside female EHS.
This is usually all you see with a scale that has been parasitized. An exit hole!

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!

Monday, July 18, 2011

Movento and Rosette Bud Mites

Field where Movento applied in Avery County.

On Friday, Jerry Moody and Doug Hundley with Avery County Extension helped me evaluate rosette bud mite control in a grower’s field. I reported on this study on June 15. Then I just pulled some shoots at random to see if I could find any rosette bud mites. But now you can clearly see which buds look like rosette buds and if there are living mites present inside the bud.

Currently our best control has been to apply Dimethoate when the new growth is out 4-6 inches. A few growers have also tried Mavrik during that time frame with some results. But these have always been with a high pressure application.

Some growers have gotten good control with Dimethoate using a mistblower if they use a lot of water per acre (50+ gallons) and/or treat twice during that June treatment window. We were interested in trying the new systemic material, Movento with a mistblower.

Don’t confuse Movento and Safari. They are two different chemicals from two different chemical families. The active ingredient in Movento is spirotetramat. It is labeled at 5 to 10 ounces per acre.

The following two statements are from the label:

“Movento is a suspension concentration formulation and is active primarily by ingestion against immature target pest life stages. In addition, fertility of adult female target pests, such as aphids and whiteflies, may be reduced.”  This means that the pest has to feed on the plant having Movento in it to work. It also means that it will take some time for the product to work, as it is affecting pest development and fertility.

“Movento must be tank-mixed with a spray adjuvant/additive having spreading and penetrating properties to maximize leaf uptake and systemicity of the active ingredient within treat plant.” We have successfully used the adjuvant Liberate (which also makes droplet size larger, making it a good choice for mistblowers) and a 1% horticultural oil solution.

When Jerry and I tried this product last year for twig aphid control, we saw one tree that had rosette buds that didn’t have any following treatment. Since we were treating in mid April, it appeared that the systemic action of the Movento was getting into the tree and preventing the rosette bud mites from developing.  It had time to work throughout May and into June to control the mites.

This spring, we got Clay Cutherbertson in Avery County to apply the product with his mistblower. He treated in April using 10 ounces per acre and about 70 gallons of water per acre. Friday we went through those blocks, and found very few trees that looked like they had rosette buds on 2011 growth, and those few buds had no live mites in them. (Actually I did see one live mite under the microscope, but it was in a fully formed, normal bud and could no longer create a deformed rosette bud).

This is just one study in one field, but it looks very promising. A spring application of Movento with a mistblower may well control two of our most difficult to control pests – balsam woolly adelgid and rosette bud mites. Twig aphid control with Movento is only fair, but in fields that had twig aphid control from the fall, or by adding another material such as Talstar which works well against twig aphid (that’s why Clay did), you can control multiple pests in the spring.

Like most studies, this little test creates some more questions. Does Movento have activity against rust mites which are quite similar to rosette bud mites? Can you treat with Movento any time of year and control the mites inside the bud? These are some things we’ll be looking at in the future. Keep checking back to the blog for more information about Movento and other chemical controls.

Friday, July 15, 2011

New Pesticide Safety Training Materials

The folks at North Carolina State University have put together a training packet for Christmas tree growers to share with their Latino farmworkers. Called the Pesticides and Farmworker Health Toolkits (click to see information at NCSU), the programs are specific to the different commodities grown in North Carolina. The standard kit includes:
--Introductory DVD for trainers,
--Flip-chart in Spanish (with discussion guides for trainers and colorful visuals illustrating the trainer’s message for the audience),
--One-page illustrated handouts in Spanish,
--Interactive materials, including jug and labels and symptom charade cards,
--Totebag.
The one for Christmas trees is hot off the presses. We used it at a Latino farmworker safety training on July 13 in Foscoe. Held at Hawk Mountain Tree Farms, the training included several stations, one of which was pesticide safety. I helped Jim Hamilton, Watauga County Director and Charles Clark and Travis Snodgrass, both with NCDA conduct the training.

Jim Hamilton explaining about chemical resistant footwear.
Charles Clark and Jim Hamilton use the flipchart to teach workers about pesticide toxicity.
In these training materials, the toxicity of different materials is related to a stop light. Very toxic materials having a "Danger" signal word have a red light, materials that have a "Warning" signal word show a yellow light, and the least toxic materials with a "Caution" signal word have a green light. The handout in Spanish is divided into insecticides and herbicides and feature the most commonly used pesticides with their respective signal words. Symptoms of pesticides exposure are also shown.

Workers can take this chart home, showing the common materials used for Christmas tree production in NC.
The flipchart also lists routes of pesticide exposure and symptoms of pesticide poisoning. Jim Hamilton also describes in Spanish parts of the body that require greater protection from pesticide exposure in the following video:



Flipchart showing routes of pesticide exposure -- dermal and inhalation. 
Fit tests for pesticide respirators were also reviewed by Travis Snodgrass. First cover the filters. If the respirator fits properly, you won't be able to breath in more air. All air passes through the filter. Second, cover where air is released from the respirator when you breath out. With that covered, you shouldn't be able to blow more air out of the mask. This demonstrates that the filters can't be bypassed.
Cover the filters and if the mask fits, you can't pull more air into the mask.
Cover where air comes out of the mask, and you can't push more air out.
The toolkits should be available soon for growers at the NCSU Toxicology Extension website. Some will be available from the county extension offices. We hope to get on video more safety trainings in the coming months and put them on YouTube so that they are available to everyone.

Thursday, June 30, 2011

Organic Christmas Tree Powerpoint

Fertilizer for the Extension Organic Demonstration
I was scheduled to give a talk at a Southern Christmas Tree Conference at the end of May in Atlanta. The conference was canceled, but I had already put together the powerpoint. It was a short talk on the possibility of growing organic Christmas trees. Thought some folks might enjoy looking at it. It's in a pdf format.

Organic Christmas Trees

Any thoughts? Questions? Anyone interested in starting organic Christmas trees?

Wednesday, June 29, 2011

Trip to the Roan

Roan Mountain is one of my favorite places. I hadn't been on the mountain for three years, so thought I would travel up there last week to see how the trees are looking.

The Roan has changed tremendously through the years. I have a bit of information about it in my history of the NC Christmas tree industry at: Chapter 2: Why Fraser Fir? This chapter goes into a lot of the natural history if Fraser fir if your interested. As far as Roan Mountain is concerned, logging had stopped by 1937 and by 1941 the US government had purchased the property. Wikipedia has a pretty interesting summary of Roan Mountain as well. Jennifer Bauer Laughlin also wrote a good book on the Roan in 1999 called "Roan Mountain: A Passage of Time."

Balsam woolly adelgid was first detected on the Roan in 1962. Trees were protected in 1963 to establish a source of seed for the fledgling Fraser fir Christmas tree industry in North Carolina. The following is an excerpt from Chapter 5: Early Days: the 1960s.

Spraying trees on the Roan in 1964.
From a forest service brochure dated 1964.
"A 25-acre seed production area was established by the US Forest Service and NC Division of Forestry (Johnson, 1980).  “Three hundred trees were marked and subsequently included in the protection zone” (Johnson, 1980, p. 16).  Those who worked on the project included Dwight Brenneman, Nursery Superintendent of the Edwards State Forest Nursery in Morganton, Bob Kellison who had been hired that year as a forestry faculty member, John Gilliam, Leonard Hampton and others presumably with the Forest Service. Trees had been thinned in the fall of 1963 to increase cone set, but the shallow rooted habit of the Frasers made them prone to blowing over (Green, 1965).


Trees were originally sprayed November of 1963 with BHC, a precursor to Lindane, and more trees sprayed along the 2 ¼ mile Balsam Road in the summer of 1964 (Green 1965). Treating these areas with insecticides and other areas in natural stands cost an estimated $100 per acre (Claridge, 1963). “Spraying was discontinued in the seed production area in 1974 after many trees had been lost to windthrow” (Johnson, 1980, p. 17). "

Roan Mountain had been the industry's most important seed source for many years. In recent years, research conducted at NCSU has determined that Roan Mountain trees were genetically inferior to other seed sources.

People line up to pull seedlings from Roan Mountain in 1978.
Collecting seed from Roan Mountain in 1997.
The Roan Mountain seedling pull has been discontinued due to lack of interest.

In 2008 when I went up to the Roan to view the rhododendron's blooming, I was struck with how healthy the trees looked on the road back to toll house. Sadly, this year most of those trees were dead. The following video highlights the regeneration of the Frasers, and the larger trees which have finally succumb to the balsam woolly adelgid and other stresses.

video

Young trees are naturally less susceptible to BWA because they produce juvibione, an insect growth regulator. This is different from hemlock woolly adelgid which attacks all ages of eastern hemlocks. Read more about juvabione on Wikipedia!

So what kinds of pests did we find on the Roan last week? We found balsam woolly adelgid, rosette bud mites, and balsam twig aphid damage. We also found some strange needle problems which I haven't seen before. We didn't see any elongate hemlock scale.

Rosette bud on the Roan.
Twig aphid damage on the Roan

Unidentified needle damage on the Roan.
We also didn't see many Fraser fir cones. There were red spruce cones developing. This seems odd because it's been a rather big year for cones in growers' fields. Guess it has to do with the heat and dry weather last year in June at lower elevations. I'll try to find some weather archives from the top of the mountain. At least I got some photos of red spruce cones. I didn't have any.

Red spruce cones
I also got to see the Gray's lilies starting to bloom. Always a pleasure to visit the natural stands of Fraser fir.

Gray's lily
The crew that went up on Roan Mountain included Brad Edwards, Jeff Vance, Jerry Moody and  my daughter Emma.

Thursday, June 23, 2011

Elongate Hemlock Scale Lifecycle

In talking with folks, I find that people are confused about the lifecycle of the elongate hemlock scale.

It is a bit confusing. The same insect can be white (for the males), brown (for the females) and yellow (for the immatures). It's hard to know if they are alive or dead. So here's a bit on the lifecycle that will hopefully make things clearer.

Life for an elongate hemlock scale starts out as an egg which is found under the protective scale of the mother. Here is a photo of the mother flipped over and broken into to show the eggs and the same photo labeled.



These eggs will hatch and the crawler will move out from under the mother scale and find a place to settle down. I actually got by accident a photo of a crawler leaving the mother. It is below. See the crawler at the bottom of the picture? Once again, everything is labeled in the second shot.



The crawler moves around until it finds a place to settle down and start moving. There it will molt, and start creating the scale covering for itself. If it is male, eventually it will fly away  so it can mate. That only happens when it is mature. If it is female, it will never move again.

The crawler is the small yellow thing.
The nymphs settle down, and then they produce the adult scale behind them. Here is a photo of one female scale. The yellow portion is the nymph part of the female, and then the brown part is produced.There aren't two scales, just one. It is all white around it because the scale has grown under the waxy cuticle of the needle. It is also almost impossible to tell if it is dead or alive. Under a microscope you can poke it with a pin and it will be moist. This one was alive when I took the photo.



The males are white. They develop into a winged insect that flies off to mate with the stationary females. You can almost think of the white scales as ultimately being a cocoon in which the male is developing. So often when you see the white scales, they are empty because the adult male has already flown off. The adult male is pictured below. This isn't my photo, but it's all I've got of the males.


Now let's put time into the picture. When does all this happen? The following are observations made by Paris Lambdin, a researcher in Tennessee.


          “EHS has two complete overlapping generations per year at sites within the southern Appalachians.”  My comment -- That means that you can find all life stages virtually any time through the year.
          “The spring peak for crawler emergence occurred in June while the fall peak occurred in late October into November.”  
          “Fall peak emergence for males occurred in August, coincident to the highest number of adult females.”  My comment -- That's why we see a second "wave" of white coming onto the trees in August. That's the second generation of males being produced.
          “Gravid adult females were most numerous in late May and October—November.”  My comment -- Gravid means they have eggs.
          “Females have three stages of development while males have additional prepupal and pupal stages.”  My comment -- That refers to the number of molts each sex goes through before maturity. For females, they are mature when they can lay eggs. For males they are mature when they emerge and fly away.
          “Each female produced 12-16 eggs which hatched over time.”
          “Males do not feed and live only 24 to 72 hours upon emergence. Although capable of flight, males tend to walk across the needles seeking out females for mating.”  My comment -- These are the adult males with wings that have emerged from the "cocoon." Some folks were finding the adult males when they were beating the foliage in the spring looking for twig aphids.

Other observations from scientific literature include:

          All life stages found any time of year (Davidson and McComb 1958) – eggs laid throughout growing season
          Mature females may often live for more than one year. My comment -- Isn't that great!
          After a month, the eggs hatch and the first instar nymphs ("crawlers") emerge and migrate to the underside of new needles. 

No wonder people were having a hard time figuring out the life cycle. It's complicated! If anyone has any questions, please let me know.