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 27, 2012

Post Harvest Pests

Heard about my first post-harvest pests today. Cinara aphids. Anyway, here are links to information about these pests.
  1. Grower information on Cinaras.
  2. Information for the retail lot operator.
  3. Retail lot information in pdf format.
  4. Photos of Cinara aphids.
  5. Consumer education information on post harvest pests including Cinaras, praying mantids, and spider mites.
If you need me to speak with retailers or consumers about this issue, email me at:

Jeff Vance is holding a bottle of insecticidal soap.
This works well against aphids and is completely safe
around children and pets. It does have a bit of an odor.
You can buy this pre-mixed in high end garden centers.

This is a photo I received from a consumer a few years ago.
Surprisingly it's never hard to ID Cinara aphids from the  strange photos I receive.

Monday, September 3, 2012

Impact on Predatory Wasps

Yellow sticky card placed in a Christmas tree that has EHS.
On January 5 of this year, I posted about the parasitic wasps I was finding on cut Christmas trees that were infested with elongate hemlock scales (EHS) (see Parasitic Wasps on Scale Infested Trees). If you will remember, Jerry Moody and I placed yellow sticky cards in cut trees to determine if scale crawlers were coming off of them. Yellow sticky cards are about 3 X 5 inches and coated with a sticky clear substance that traps insects once they step onto it. The yellow is particularly attractive to many insects. During our little study, there were only a few wasps per sticky card coming out once the trees were displayed in water in a warm room just like they would in someone's house.

These parasitic wasps are very important to control of the EHS. They are very, very small -- the size of a single scale. You'd never see them flying around, and in fact you have to use a microscope to see them on the yellow sticky cards. These wasps, Encarsia citrina, are available commercially and are often used for whitefly control in greenhouses. But they also love scales. Whenever you see a scale that has a round hole in it, you know that one of these wasps has developed inside it and killed it.(Think ALIEN with Sigourney Weaver!) I especially enjoy probing into scales this time of year and finding the immature wasp inside one. Sometimes the tiny little wasps even move their heads! (Nature is so cool!)

This scale has been parasitized. The arrow points to the exit hole the wasp made to get out
once it had fully formed.
The arrow points to a wasp that is still forming inside this scale. The eyes are to the left.
Over the last week, I've put out some yellow sticky cards in trees infested with scales in an Ashe County Christmas tree field (pictured up top). Travis Birdsell, the new county agent in Ashe County and I looked at these cards on Thursday after leaving them for 48 hours. I was amazed at how many wasps there were! We put two cards in one tree and there were 56 wasps on one of them and 34 on the other. In a second tree we had one card and it had 15 wasps. This was in a field where there were some scales, but they had never become really bad as they are in some fields.

I was surprised that there were so many wasps out now. So I became curious. Could I see a difference in the number of parasitic wasps in fields that had been treated with a synthetic pyrethroid compared to those that hadn't? I've thought for a long time that the increased use of the bifenthrin products in particular might be causing a lot of the increase problems in scales.

It just so happened that Jerry Moody and I had created the perfect place to test out this theory. We were working in a small field of trees in Avery County where few insecticides had been used and scales had become a problem. I already knew there were lots of parasitic wasps as I had seen them inside the scales. We had sprayed a block of these trees two weeks ago with Safari and a bifenthrin product, in this case, OnyxPro. We are treating a different block of trees every two weeks to see how late in the season we can get good scale control.

So on Friday, when we were making another treatment, I put a yellow sticky card in three untreated trees and three trees treated two weeks ago with Safari + OnyxPro. The two sets of trees were probably only about 75 feet apart. Today I looked at the cards (after 72 hours) and was amazed at the results.

There was an average of 45 wasps on the cards placed in untreated trees (79, 35, and 22) and an average of 5 on the trees that had been treated (10, 3, and 1). That is a 90% reduction in the wasps just two weeks after treatment! And though I didn't look at scale control, I am sure there is very little yet as Safari takes a long time to work.

I plan on looking more at this issue, trying to evaluate different chemical combinations put out at different times of year to see what the optimum time is to get control of scale without doing away with the parasitic wasp. But the early take home lesson is that the use of synthetic pyrethroids can have a profound affect on these important natural controls. Hopefully in the coming months we can determine when these materials can be used with the least negative impacts.

Monday, July 16, 2012

New Website

I've just completed a new website that will help sort through all the pest control options.


There's lots of information on these pages, so skim through them all. If you see any errors let me know. If you're having trouble navigating, let me know as well. It was hard deciding how to set up the navigation, so I'd be happy to change anything to make it easier.

Sunday, April 22, 2012

Celebrate Earth Day with a Christmas Tree

This week while scouting a field for twig aphids and mites, I came across this little nest full of eggs. It reminded me of how Christmas tree fields are home to many creatures -- a perfect reminder of Earth Day.

The most important creatures that tree growers invite into their tree fields are natural predators, brought in when ground covers are managed rather than killed. The next photo is from a field I was also in last week, showing a diversity of flowering ground covers.

That means that tree growers don't have to purchase natural predators like the lady beetles sold here for home gardens. Predators are attracted to the diversity of flowers and insect activity in the ground covers and will feed on any aphids or mites found in the Christmas trees themselves. It's free pest control.

One of the lessons from the Extension organic field in Alleghany County has been that the ground covers that come in when low rates of Roundup are used are far superior to all the grass that grows in the organic trees. After all, we grow grass in our lawns because grass tolerates mowing. Mowing ground covers in the organic trees has promoted grass and actually decreased biodiversity in the ground covers as compared to the lower portion of the field where conventional practices have been used up until this year. In this photo, you can clearly see the line where the clover stops and the grass starts. That's the line between the trees that have been grown organically since 2008 and those that are switching to organic production this year. Mowing promotes grass and it has certainly taken over to the detriment of the trees and the natural predators as well. (For those wanting to grow Fraser fir organically, it will be important to plant clover and other beneficial ground covers in a field the year before the Christmas trees are set -- something that wasn't done on this site. But that's for another blog entry!)

These ground covers, however, are also forage for bees. Clover, wild mustard, and purple deadnettle especially bring the bees in. Protecting bees can be as simple as choosing the time of day when you spray with an insecticide. Spraying trees in the late afternoon or at night for mistblower operators, is a good way to avoid problems with bees. Switching pest control to the fall is also a good way to avoid problems with bees. Be aware if someone has a commercial or even a hobby hive near your tree field. For fields close to bee hives, a mid-March application of horticultural oil will control most Fraser fir pests without causing a problem with bees at all.

April 22 -- Earth Day -- might seem like an odd time to think about Christmas trees. But those involved in the Christmas tree industry in western North Carolina know that every day is Earth Day in a Christmas tree farm!

Friday, April 20, 2012

Strange Spring: The Continuing Saga!

This spring continues to be unique. I was in a field in Avery County at a fairly high elevation yesterday, and one in Transylvania County at a low elevation today, and bud break was about the same. Only a few trees had broken a few buds in both fields, but it looks like the trees are ready to pop. I think the cooler weather this week has slowed things down.

But don't expect the cooler weather to slow the bugs down. The twig aphids are reproducing. This typically happens right before bud break, and they are doing the same again this year. The difference is that it appears that bud break and perhaps shoot growth might take longer than normal. That means that the trees will be at their most vulnerable to twig aphid attack for a longer period of time. Also, the warm spring has allowed for good aphid survival and reproduction. It all adds up to a potentially bad year for twig aphids.

That is why I've always warned people that if you are beating the foliage and finding even a few aphids, they will reproduce and end up being a problem. Each female aphid can produce 10 to 15 live young -- making what you saw last week 10 times more this week.

Rust mites are also quite active and will remain so until temperatures really warm up.

The good news is there has also been a lot of rain, which will help the trees grow out of any twig aphid damage. The following aren't very good photos, but they illustrate my point. The first picture is of a tree with twig aphid damage in May. The second is of the same tree in July. Most of the damage has straightened back out.

Shoots actively growing show lots of needle curl...

... but the mature growth has little damage.
So don't get too concerned with twig aphids. Use your judgement. Still, it's a good idea to recheck the trees that you plan on cutting this year that are your best trees, and treat them if necessary. Dimethoate is a good choice at this point as it will penetrate the cones and any broken buds. However, remember that Dimethoate is quite toxic, and is especially a problem when bees are active (which they are now in ground covers). Consider spraying later in the day, or if you are using a mistblower, of an evening.

With as much wind as we've been having this spring, I know how hard its been to get sprays out. Just remember, that poor conditions for spraying will give poor control results. There's little need to waste time, money, and put the environment to risk by forcing a spray job under windy conditions.

Let me know if you have any questions, and good luck!

Monday, April 16, 2012

Who Can Learn to Scout?

ANSWER: Anyone!

Yesterday, Brad Edwards showed a picture of his girls scouting for pests. His 6-year-old was identifying twig aphids and elongate hemlock scale, and showing the grower what to look for and what to do. I love it! Way to go girls!!!

Sunday, April 15, 2012

The Early Spring: A Message From Doug Hundley

Doug Hundley, Avery County IPM Technician, sent out this message to his IPM folks. I thought it was so good, I've copied it here for everyone.

The only other thing I would add to this is the need to be aware of bees in the field when you spray. Don't apply products like Dimethoate when bees are actively foraging. I posted something about this a couple of weeks ago in: Bee Careful, but it bears repeating.

Doug Hundley (left), talking with Brad and Scott about scales.
Good day everyone,

How early the Fraser budbreak will be this year will obviously be a record breaker; like everything else that is happening this spring.  This is hardly news worthy now.  The frost events this last week were, of course,  tough on the fruit and flowers but we lucked out on the Fraser buds in Avery County.  Below 3,000 ft.elevation, light damage may have occurred.

Today I wanted to know if you are seeing what I am seeing out there.  The cones have emerged and have made a good hiding spot for any BTA in the trees.  As you know, from this point on, any BTA treatments need to include Dimethoate and be applied with a high pressure hose sprayer.  The cones should be targeted specifically to get adequate penetration.  Of course if you have the time to remove the cones and carry them out of the field, a mistblower application could work for a few more days.

I said a few more days because it looks to me like the new growth buds will be breaking this week.  Budbreak is already underway below 3,000 ft. ; elevation in locations like Mountain City.  As the buds emerge, hose applications that include Dimethoate will continue to be somewhat effective for about 2 weeks into budbreak.  After that, we have no other options.  I know some of you are adding Safari to your spring BTA treatments.  We really need to know how well Safari works in April and letting us know when and where you are treating with Safari will help very much.  Please respond via email and we'll monitor your results over the summer.  Thanks in advance!

The high winds and early budbreak have made it another tough year to treat for BTA in the springtime.  I know many of you are enjoying the benefits of having made your BTA treatment last summer or fall.  What a great development this has been.  However, if you haven't already heard, that Hemlock Rust Mites are having a very good year.  The rust mites have enjoyed this perpetual spring that began in January.  With temperatures forecasted to top out in the 60's for the next 7-10 days, we don't expect the rust mites to do anything but increase. 

I know that many of you have been treating for BTA in the Fall for several years and have a sense of security that it always works, which it usually does.  However, never forget the Rust Mites, especially if you applied Wisdom or Asana last year between the months of April and July.  I've seen not only 25 mites per needle but damage beginning to show on the foliage. 

Everything is happening early this year.  That may include Rust mite and spider mite damage as well.  Despite our successful spray programs there is always an important need to scout.  Please reply to me with your own observations.  Feedback from you guys has been very helpful and always will be.

Sincerely,  Doug

Again, thanks Doug for your observations and recommendations. And Bee Careful out there! This spring certainly has been challenging, but if we keep getting rain, don't worry too much about twig aphids! I'd worry more about rust mites!

Wednesday, April 11, 2012

Hemlock Rust Mites Early This Year

The HRM is certainly enjoying this spring. This morning I found a field that had rust mite damage already on 2011 growth. Doug Hundley said he saw some rust mite damage last week. Folks, that's really early! So, be sure to scout for mites this spring.

Remember that Dimethoate will control rust mites, but not the eggs. Envidor and Sanmite control both rust mites and spider mites -- all stages. Horticultural oil and sulfur give excellent control of rust mites. Oil will give pretty good control of spider mites too if you have good coverage. Apollo and Savey do not control any stage of rust mite -- not the egg and not the mites. They are only effective against spider mites. The same is true, of course, of Talstar (bifenthrin).

And no, don't expect this cold snap to slow rust mites down. Only hot weather weather does that! And even though it's been warm lately, it still gets cold at night. Perfect rust mite weatheer.

The following are some photos I took this morning.

This shoot already has bronzing from the rust mites. Compare it's color
to the greener needles around it.
Jeff Vance easily knocked off damaged needles from the 2011 growth.
My Samsung Android amazes me sometimes. I took this photo with my phone.
You can actually see the rust mites on the needle.

Safari Control of HWA

In February 2011 when this photo was taken, these trees had no HWA.
In June of 2010, I made a post on some hemlocks at my office that I had treated for HWA. (See post: HWA Control).

I looked at those trees today and they are covered with HWA and with EHS. The controls worked for 3 years, which wasn't bad.

It seems to me like there is a lot of HWA this spring -- not just on these trees but everywhere. It might be because of the warm winter.

Has anyone else observed how long Safari has controlled HWA? If so, make a comment about your situation.

Tuesday, April 3, 2012

Bee Careful!

Though this picture is of a bee in clover, there are many other flowering
plants in Christmas trees that bees may be attracted to.
Christmas tree pests are very active this spring, and growers are finding they need to treat for mites and for twig aphids. Thanks to chemical mowing, Christmas tree fields are full of flowering ground covers, especially wild mustard and purple deadnettle. These are favorites for bees. That's great for wildlife and biodiversity, but it presents a problem when trees need to be treated with an insecticide.

I wrote the following article for LIMBS & NEEDLES in 2008 with the help of Dr. David Tarpy at NCSU. The information is still appropriate. It gives good information on how to protect the bees that are in your Christmas trees. Basically, the best way to do this is to avoid spraying when bees are actively foraging. Target treatments of an evening or night.

There were several products we use today that weren't mentioned in the article because they weren't used at the time this was written.

  • Safari (dinotefuran) is highly toxic to bees.
  •  Movento (spirotetramat) is not toxic to the adult bees, but if it is taken back to the hive, it will affect how the bee larvae develop. 
  • Envidor (spirodiclofen) is slightly toxic to bees and may cause a problem in contaminated pollen and nectar. 
  • None of these products should be sprayed in areas where bees are actively foraging.

Bees and Trees -- LIMBS & NEEDLES article from 2008

By Jill R. Sidebottom, North Carolina State University

We have lots of clover in our Christmas tree fields now. That’s great news. Clover adds nitrogen to the soil and reduces erosion. It also provides forage for bees. That’s a wonderful thing – most of the time. However, when a Christmas tree grower needs to apply an insecticide, having bees actively foraging in the field can present a problem.

Being insects, it is perhaps not surprising that most insecticides are toxic to bees. Even some organic insecticides will kill bees. The wrong pesticide, applied at the wrong time, will not only kill the bees foraging at the site but can be carried back and kill the entire colony. The good news is that pesticide poisoning of honey bees can usually be kept to a minimum if beekeepers and pesticide applicators take certain precautions.

Most pesticide labels have a special warning about bees and other beneficial arthropods. For example, the label from Dimethoate reads as follows:

This pesticide is highly toxic to bees exposed to direct
treatment or residues on blooming crops or weeds. Do
not apply this product or allow it to drift to blooming crops
or weeds if bees are visiting the treatment area.

This language clearly places the responsibility for the safe use of this pesticide squarely on the applicator. Beekeepers can help applicators by making them aware of their hive locations, covering their hives with wet burlap, or even moving the hives during times of pesticide exposure. But the responsibility ultimately falls back on the pesticide applicator to make sure that bees are kept safe.

In the NCSU beekeepers notes, “Reducing the Risk of Pesticide Poisoning to Honey Bees”  contains a table with different pesticides and their relative toxicity to honey bees. I have reproduced the tables, in part, showing the materials that are used in western North Carolina on Christmas trees.

GROUP 1 – HIGHLY TOXIC. Severe bee losses may be expected if the following pesticides are used when bees are present, or if the product is applied near beehives or within a day after application to foraging bees in the pesticide application area.

  • Abamectin
  • Acephate (Orthene)
  • Carbaryl (Sevin)
  • Chlorpyrifos (Lorsban)
  • Dimethoate
  • Imidacloprid (Provado, Merit)
  • Malathion
  • Permethrin (Astro)
  • Spinosad
  • Thimethoxam (Flagship)
 GROUP 2 – MODERATELY TOXIC. These pesticides can be used in the vicinity of bees IF dosage, timing, and method of application are correct; but these products should never be applied directly on bees in the field or at the colony location (apiaries).

  • Bifenazate (Floramite)
  • Disulfoton (Di-Syston)
  • Endosulfan (Thiodan)
  • Fluvalinate (Mavrik)
 GROUP 3 – RELATIVELY NONTOXIC. These pesticides can be used around bees with a minimum of injury if the dosage, timing, and method of application are correct. Never apply pesticide directly to the beehive.

  • Diflubenzuron (Dimilin)
  • Esfenvalerate (Asana)
  • Pymetrozine (Endeavor)
If the pesticide you are interested in is not listed here, you can sometimes find the LD50’s for bees under the MSDS (Material Safety Data Sheets). A material is considered ‘highly toxic’ if the LD50 is less than 2 µg (microgram or 1/1,000.000 of a gram) per bee. It is ‘moderately toxic’ if the LD50 is 2 to 10.99 µg per bee; ‘slightly toxic’ if it is from 11 to 100 µg per bee; and ‘practically non-toxic’ if it is from 50 to 100 µg per bee. For instance, the contact LD50 for bifenthrin (Talstar) is reported as 0.01462 µg/bee, which would make it highly toxic.

The LD50’s for bees can be somewhat misleading, though, because they express the pesticide toxicity to the individual bee. A product that is moderately toxic but that is applied in a form that is similar to pollen and is collected and concentrated along with the pollen can kill the entire colony.

On the other hand, highly toxic materials may cause less of a problem if bees are not actively foraging in the area. Be sure to check fields the day before spraying to determine if bees are actively foraging. For instance this summer, some of the clover flowers are drying up because of the drought, and bees are no longer present. Also, if materials are applied in the late afternoon (after 3 pm) or even at night, the impact on bees will be reduced. Some growers have successfully used Dimethoate, for instance, near hives if the material is applied in the late evening and is dried before the bees start foraging the next day.

Reducing drift is also important in reducing the likelihood that the material contacts beehives. Air-blast sprayers are more dangerous than pressurized-pump sprayers. If a pesticide application is being made by air, then it is the contractor’s responsibility to notify any beekeepers that have “registered” apiaries (one or more hives of bees) within 2 miles of the area to be aerially sprayed. These regulations are defined in the N.C. Pesticide Laws and the person responsible for the notification is the person who contracts for the aerial application.

More information of bees can be found at the apicultureprogram at NCSU. Another important link is to the North Carolina State Beekeeper’s Association. This is a good place to look at see if the county you have Christmas trees in has a beekeepers association that you can contact about the local of hives near your Christmas tree fields. Finally, you can contact the NCDA&CS ApiaryInspection Service for official apiary records and registration.

The NCCTA is currently advertising the environmental benefits of Christmas trees. If bee kills are associated with Christmas tree production, however, it will be hard to defend such a claim.

Special thanks to David Tarpy, Associate Professor and Extension Apicolturist, NCSU, for helping review this article.

Thursday, March 22, 2012

Saving the Hunger Games Set!

The same chemical that you may be using on your cat or dog to control fleas is helping to save centuries old hemlocks in the DuPont State Forest in western North Carolina.

Today I helped Brian Heath and Craig Lawing with the NC Forest Service train staff members at the DuPont on how to treat hemlocks for hemlock woolly adelgid (HWA) using a trunk application of Safari (dinotefuran). We just happened to be working at Bridal Veil Falls -- soon to be famous as a filming location for "The Hunger Games" which comes out this weekend.

The DuPont State Forest started controlling HWA several years ago. This has included releasing the predatory beetles, Sasajiscymnus tsugae, and applying the insecticide imidacloprid, often using CoreTect tablets (click here for the label) which are buried in the soil at the base of the tree. Still there are many trees that haven't been protected -- many of which couldn't be treated with a soil application. Sadly, there are still many trees at the DuPont which are in a state of decline.

Safari is more versatile than imidacloprid, as it can be applied as a spray directly to the trunk of the tree. This systemic insecticide is then taken up by the tree, moving to the foliage where the adelgids are killed. It also works well against elongate hemlock scale, another introduced pest that is commonly found in the DuPont. Left unchecked, these pests can kill eastern hemlocks.

Today we worked with two educational rangers with the Forest -- Eric Folk, who worked with the film crew, and Roberta Belcher. We showed them how to calculate the rates for application and how to apply the chemical with a backpack sprayer. Below are some pictures showing the process and the state of some of the trees.

First, the trees are measured to determine the rate. Here Brian
and Craig are determining the tree's diameter while Eric writes down the measurements.
It is important to keep good records as treatments may be several years apart.
Some of the trees are in good condition because of past imidacloprid applications.
This is one of the better looking hemlocks I've seen lately.
 These trees didn't look as good. One of them is already dead.
They had never been treated with imidacloprid as there is hardly any soil for
a soil application. Trunk applications with Safari are the only
hope of saving them.
Eric applies the Safari while Roberta times the application and keeps up with records.
The insecticide is only applied to the trunk of the tree.
You can see where the tree is wet.
The chemical is very safe -- remember it's used in products you can put on your pets.
Roberta has been working at the DuPont for more than 10 years. She said when she first started working, you couldn't even see the falls from the parking area. Now, with so many hemlocks in decline, you can. Hopefully with these and other control methods, these stately and important trees will thrive once more for generations to come.

Wednesday, March 21, 2012

A Buggy Spring!

I revisited the field I was in last week to look again at twig aphid hatch plus going to a second field today. One field is in Mitchell County along the Parkway; the other is in a high elevation site in Avery County. The following are a few observations.

  • BALSAM TWIG APHIDS are at 90% hatch. The high elevation site actually had a slightly higher twig aphid hatch! If the next week continues warm, twig aphid should all be hatched out by April 1. This only happens once every 10 years or so. Usually it takes until April 15. If using Thionex (endosulfan) or Di-Syston 15 G, wait until after April 1 to treat. All other products can now be used at any time .
  • SPRUCE SPIDER MITES are hatching out. They are all at the immature stage -- no adults yet. I even saw some that were encysted -- that means they were sitting very still as if dead while they molt.
  • HEMLOCK RUST MITES continue to increase. At the one field in Mitchell County, I didn't see a single rust mite in my samples taken on March 13, and now about 20% of the shoots had just a few rust mites on them. That's a pretty impressive jump!
The following are some suggestions for pest control this spring:
  1. Start scouting now for twig aphids and mites. Don't wait until the middle of April. If you do it now, you will have more time to do something about a mite or aphid problem.
  2. Be sure you to scout a second time before bud break to make sure something hasn't become more of an issue if you aren't planning on putting out an insecticide this spring.
  3. Scouting doesn't have to be a big production either. Just going to key fields and blocks, getting out of the truck and walking to half a dozen trees should tell you all you need to know.
  4. Don't just expect fall pesticides to control twig aphids -- scout to make sure they have worked.
  5. Be aware of the weather. If it stays pretty, those few mites and aphids this week will be at very damaging levels by bud break. What would stop this is several days in a row of wet weather or a return of winter for a few days.
  6. Remember that Dimethoate will only give a knock-down of mites. If the weather stays favorable (which so far it has) those mites will come back from the eggs. However if all the spider mite eggs are hatched and they haven't yet started to lay more eggs, then a single treatment of Dimethoate should work well. This also means that Apollo and Savey, products that only work on eggs and immatures, will not need to be mixed with another miticide such as Dimethoate to work. But this will only be true for about another week. For a list of miticides and how they work see Christmas Tree Note # 29: Spruce Spider Mite on Fraser Fir
  7. Remember to use up your Thionex before July 31 of this year. Wait until April 1 before using it if you want twig aphid control.
If you have any questions, email me at

Good luck this buggy spring!

Tuesday, March 13, 2012

Spring Bugs

SUMMARY: With the spring weather, many pests and predators are becoming active. Twig aphids are already starting to hatch which is earlier than most years. Rust mites are very active. Cinara aphid populations may be crashing from earlier this year with increased activity from lady bugs. Be sure to be in your trees scouting so that you'll know if you need to treat and can choose the best materials for control. For more details, see below!

Spring has sprung as they say and bugs are no exception. Today I visited two fields in Mitchell County with Jeff Vance and found a lot of activity.

Cinara aphids. In one field, we've been following a heavy incidence of Cinara aphids since the first of the year. Most of these aphids are dead already from natural causes. We saw several Harmonia lady beetles feeding on them. We also found some white sap or honeydew on some of the needles. I tasted it and it was definitely sweet. There's a lot of sooty mold too on the trunks and branches --  parting gift from these pests! Below are some photos.
Most of the aphids are dead, but there is one in the middle right hand that is still alive.
White sap or honeydew on the needles where Cinara aphids have been feeding.
Harmonia lady beetle.
I think this lady beetle is infected with a fungus.
Balsam twig aphids. The aphids have started to hatch already. They are about a week to 10 days earlier than normal. I would estimate that 25% of the eggs have hatched already. I did see a dead aphid and an egg that looked like it might be dead -- black inside. A lot of rain will be hard on the aphids and some will die. A cold snap will kill many too if we have one.

However, I am afraid that since the spring is so early and it is staying warm, that twig aphids may be bad this year. Be sure to scout in fields where you treated last fall with bifenthrin products such as Talstar to make sure that you have good enough control. The warmer it is and the longer time from egg hatch to bud break, the longer the aphids will have to mature and reproduce. This may be the year that fall twig aphid controls fail us, so be sure to keep looking!

If you are treating this spring for twig aphids, you can start treatments any time . The only exceptions are Thionex and Di-Syston. With these products you need to wait until all the twig aphids have hatched, but that may be within two weeks!

Hemlock rust mites. Another pest that really likes the early spring are hemlock rust mites. In one field I was in today, the rust mite population was almost at treatment threshold. It was at 60% incidence and one shoot had at least 8 mites per needle.

Rust mites like spring and since we are having a pretty one, they will most likely be bad. They haven't been the last few years, so don't be caught off guard. Be sure to scout fields and treat for them if necessary. What are the best materials for HRM control? Horticultural oil, Envidor, and Sanmite are three of our best products. Dimethoate knocks rust mite problems down, but they will rebound. In fields with rust mites, be careful about using synthetic pyrethroids (Asana, Astro, Talstar, Wisdom, and Sniper) as these products will make rust mites worse. They may also make elongate hemlock scales worse, so only use them when necessary in the spring, or better yet, save their use until fall.

Spruce spider mites. I saw quite a few spider mite eggs today, but no mites that are hatched out yet. I do know of some folks that have seen mites crawling. If the weather continues warm, I'm sure it won't be long until they are active.

Twice stabbed lady beetle. We also found a couple of twice stabbed lady beetles active in trees that have elongate hemlock scales. Here is a photo.

From this angle you can only see one of the red spots.
Still not a bad shot considering I was using my cell phone!
What's the take home lesson with all of this? It's time to scout, of course!! Be sure to get out in your trees over the next couple of weeks to see what's active. And pay careful attention to rust mites.

Wednesday, March 7, 2012

Safari for Scale Control

This is my 100th post on this blog!!! 
Thanks for all the support with this endeavor!

Elongate hemlock scale (EHS) is on everyone's minds these days. In some Christmas tree counties in western North Carolina, as much as 85% of the fields are infested with scales. EHS is difficult to control, but the good news is, with scale control comes control of many of our other pests of Fraser fir including balsam woolly adelgid (BWA) and balsam twig aphid (BTA).

Safari (active ingredient: dinotefuran) is a new material recently labeled for Christmas trees. You have to have a copy of the supplemental label for use in Christmas trees.
Safari is a systemic and works well against BWA and EHS. The following are some of the lessons learned in 2011 in using Safari for EHS control.

Lesson #1: Trunk applications haven't worked well.

Applying Safari to the trunk
This method of application would be preferable because it is easier and it would result in the least impact on the parasitic wasp, Encarsia citrina, that attacks the scale. The recommendation was to apply Safari to the lower trunk of trees using a backpack sprayer and a rate of about one pound per acre.

Several growers tried this application method. I also put out several trials in Mitchell and Avery Counties. In our trials, we used a backpack sprayer for application, as well as a high pressure sprayer -- in some instances wetting the entire trunk. Unfortunately, despite the application method or timing, trunk treatments haven't worked well for us in NC. In 2012, I want to look at high rates, but for right now, foliar sprays of Safari are best.

Lesson #2: Full rate and good coverage give best results.

To date, the best EHS controls in North Carolina have been with a high pressure sprayer and full foliage coverage using 8 ounces of Safari per 100 gallons. This has ended up with a rate of as much as two pounds per acre. This application method has worked well from mid-May through August. When used in early October, control was poor.

An August application combining Safari with a bifenthrin product such as Sniper would control almost all Fraser fir pests --  EHS, BWA, BTA for the following year, Cinara aphids and spruce spider mites (SSM).

Lesson #3: It takes a while to work.

The "white" from the males
In my February 9, 2012 blog post, "Working with Safari," I described how control of Safari improved over time. In fact, it can take as long as four months.

This has made several people think it would be better to put Safari out earlier so it will have time to work. Of particular concern are the male scales that create the white on the foliage. But though the product takes that long to work fully, it is primarily the female scales which are toughest to kill that require the full four months to die. The male scales and crawlers are typically all dead within a month and even many of the female scales. So don't think you have to spray in April to prevent the male "white" on the trees. Even trees treated in August looked great by harvest a couple of months later.

Lesson #4: Natural enemies are important.

A wasp caught on a yellow sticky card.
It is the size of a gnat.
Probably the most important natural enemy of the EHS is the parasitc wasp, Encarsia citrina. This wasp lays its egg inside the immature female scales and develops there, eventually exiting as a full grown wasp from a round hole it makes in the scale's outer shell.

The following website has information about this scale: Entocare, biological pest control. (Please note that this website is mentioned for educational purposes only. The pictures are really nice. There has been no research in releasing Encarsia into Christmas tree fields).

But other predators are important too including lacewings and the twice-stabbed lady beetle.

How can you protect these natural enemies?:
  • First of all, only use an insecticide when you really need to. Scout to determine the need for control. 
  • Don't worry about BTA and mites in young trees. 
  • Reserve the synthetic pyrethroids such as Wisdom, Sniper, Talstar, Asana and Astro to the fall when they have less impact on predators.
Questions that still remain.

There are several questions about using Safari.
  1. How well would it work with a mistblower application? Many growers are set up to use a mistblower. If you would like to help us evaluate Safari applicaitons for scale control using a mistblower, let me and your county extension agent know. We'd love to work with you and follow up to see what works and what doesn't.
  2. What if you have to control BTA in the spring? Can you use Safari plus another product for BTA control and still get good scale control in April? If you're interested in trying this, again, let us know so we can follow results.
  3. Can you wait until September to treat? A September treatment would fit in better with most people's production schedule than an August treatment. First of all it's usually cooler. Secondly, Cinara aphid control would be better in trees to be harvested. Also, there would be less impacts on predators. This is something I plan on looking at this September.
  4. Would a higher rate of Safari work when applied to the trunk of the tree? Again, this is something I plan on trying -- targeting the highest allowable rate which is 2.7 pounds per acre per year.

Tuesday, March 6, 2012

Horticultural Oil

Now is a great time to apply horticultural oil for control of Fraser fir pests. Horticultural oil is the workhorse of organic pest control of Christmas trees. But even if you aren't growing organic certified trees, it provides a good way to control most pests. It can control balsam woolly adelgid (BWA), balsam twig aphid (BTA), spruce spider mite (SSM), hemlock rust mites (HRM), and elongate hemlock scale (EHS).

Oil burn on needles
How oil worksOil controls pests by smothering them. Therefore, you have to get complete coverage of the tree so that pests on all surfaces are coated with the oil solution. For pest control, a 2% solution of oil (that is 2 gallons in 100 gallons) is required. At this concentration, however, the tree may be damaged. Needles may turn brown and drop off the tree.

Types of oil. Not all oils are alike. To get the best pest control without foliage burn, use a highly refined horticultural oil. These are often called summer oils. Do not use a dormant oil as these will cause foliage burn. Look for oils with at least 92% unsulfonated residues on the label. But the higher, the better! It will list this value under the active ingredients.

Encapsulated oil -- a new type of oil. There is a new type of oil on the market called Saf-T-Side oil. The encapsulation process results in an oil that mixes with water with water and won't cause burn. This is more expensive than regular oil, but you will not need good agitation in the spray tank.

Applying oil. Typically a high pressure sprayer will give better coverage. If a limited number of trees are being treated, you may also use a backpack mistblower. Treat trees from opposite directions to get the best coverage. If you are controlling BWA, you have to wet the tree all the way to the trunk.

The encapsulated oil can be used with any type of sprayer. Other oils should only be used if there is good agitation in the spray tank. A paddle type agitator is better than by-pass pressure recirculating into the tank because the agitation is continuous. The oil and water can separate in the hose if you stop spraying for awhile, so if you do spray what's in the hose back into the tank to remix the solution.

Twig aphid egg killed by oil
What oils will and will not do. Horticultural oil has no residue. It only kills on contact at the time of application. Control of some pests is excellent, but control of other pests is not as good. However, if oil is used each year, pest numbers will continue to be suppressed.

A 2% solution of oil applied in mid-March will do a good job of controlling the following pests:
  • All stages of HRM -- actually oil works as well as expensive miticides when controlling rust mites
  • BTA eggs
  • SSM eggs
  • BWA crawlers, nymphs, and adults though the adults are covered with white wool and are therefore harder to wet.
  • Cinara aphids
Control of the following pests is not as good. A 2% solution of oil will only suppress the following:
  • BWA eggs – however, there shouldn’t be any BWA eggs present in mid-March
  • BTA nymphs or adults. Therefore be sure to treat before the twig aphid eggs start to hatch
  • EHS -- this is really too early in the year to get good EHS control. You can treat for this pest in the summer with oil, but problems with burning foliage increase in hot weather.
Be sure to keep scouting through the spring to make sure treatments have worked.

Monday, March 5, 2012

Getting the Most Bang From Your Pesticide Buck

At the North Carolina Christmas Tree Association meeting in Boone on Thursday, March 1, Doug Hundley, Brad Edwards, Brian Davis and I talked about getting the most out of the pesticides you use to control pests in Fraser fir. The following is an outline of what we talked about.

First some updates:
  1. The uses of endosulfan (Thionex) are cancelled as of July 31, 2012, so if you have any of this product, use it this spring or dispose of it properly. I blogged about this on June 11, 2010
  2. Sniper (active ingredient bifenthrin) has a new Christmas tree label. Click here for the Sniper label.
  3. Safari (active ingredient dinotefuran) has additional labeling for Christmas trees. Click here for the supplemental Safari label. You need to have this in your possession if you use this product on Christmas trees.  I blogged about this on January 5, 2012
  4. A combination of Safari and Sniper controls multiple pests. With the Safari, you get elongate hemlock scale (EHS) and balsam woolly adelgid (BWA). From the Sniper you get BWA, spruce spider mite (SSM), balsam twig aphids (BTA), and Cinara aphids. Using this in August to early September provides the best control of most Fraser fir pests without creating more problems with rust mites (HRM) and having the least impact on predators. About the only pest that these will control control are HRM and rosette bud mites (RBM).
Next, what will always be important: 

  1. Cultural practices. Using proper cultural practices prevents a lot of pest problems. That's the biggest wheel of the pest control machine. There are many cultural practices that help us with pest control. We mentioned a couple of them at this meeting.
    1. Chainsaws. Brad talked about this one. The hardest to control pests like BWA, EHS, and RBM can be partially controlled by cutting out heavily infested trees. Some growers have even harvested a field just using this method of pest control without ever using a pesticide. And even if you do spray, it will help the control last longer because you've gotten rid of a big source of reinfestation. After all, nothing kills 100% of the bugs.
    2. Nitrogen. Brian talked about the fields of young trees where they are first seeing EHS were fertilized with 18-46-0. That's because when you're feeding your trees, you are also feeding the pests! With good clover groundcovers, consider skipping nitrogen applications until the trees near harvest.
  2. Scouting. Scouting is the steering wheel for the pest control machine. Identify the major pests -- RBM, EHS, and BWA. Then as trees near harvest, keep an eye on aphids and mites. Brian told the story of watching SSM populations crash in trees last summer because it was wet and humid and he was seeing the predatory mites. He ended up not treating thousands of trees because he knew through scouting that natural controls were working.
  3. Coverage. The smallest wheel of the pest control machine are pesticides. But if you're going to use them, be sure you don't waste them. Safari is a good systemic. But even with this product, we're finding that the best controls of pests like EHS happen when the grower gets really good coverage.
  4. Natural predators. Protect them so they can protect you. We are finding a lot of the EHS parasitic wasp, Encarsia citrina. Lady bugs, lacewings, hover fly larvae, predatory mites -- they are all important. So how do you protect them? 
  5. A great home for predators!
    1. Don't use a pesticide unless you have to. Scout first, only treat for what you have. And don't try to overprotect young trees. A few aphids and mites in them won't hurt one bit.
    2. Keep your groundcovers going. That provides food for predators and greater biodiversity.
    3. Switch to treating in the fall when predators aren't as active.

What are your pest control priorities?

If you have to treat for RBM, you have to treat in a very narrow window. The second priority would be EHS control. If you don't have these but have BWA, then treating in the fall is a great option. And don't worry about aphids and mites until you are nearing harvest. How do you know what your priority is? You scout of course! 

In the next few weeks, I plan on launching a new website that goes over all the treatment options -- pesticides, times of year -- to control all Fraser fir pests. I'll blog about it when it goes public. 

Modified Treatment Wheel

I showed this modified color wheel at the North Carolina Christmas Tree Association meeting in Boone on Thursday, March 1.

We use this wheel to show Christmas tree growers when you can treat for the various pests. Based on what we were seeing last year, I modified the timeline for the elongate hemlock scale. We've been seeing good control from mid May through August. Spraying before bud break and later in September probably won't work as well, though it may fit better into your spray schedule -- hence the dotted pink line. If you don't have twig aphid control in market size trees, you might need to treat before bud break. The fall treatment window in September is better for protecting natural predators as well as Cinara aphid control. We'll continue to evaluate control during those treatment windows in 2012, so if you do treat then, let us know so we can follow how well its been working.

Abandoned Christmas Tree Program

An abandoned Fraser fir Christmas tree field which harbors balsam woolly adelgid.
This past summer, a request was received by the N.C. Natural Resource Conservation Service to begin a a cost share program to clean up fields of abandoned Christmas trees in western North Carolina. The concern of disease and insects building up on these abandoned trees and then moving into plantations that were being cared for was what led to this request. The program has been approved and is now available to landowners in western North Carolina. The following are some of the specifics to the program. For more information or to enroll, you will need to contact your local Soil and Water Conservation office.

Removal of abandoned Christmas trees to reduce sedimentation. An abandoned tree field may consist of trees of any size where interest has been lost to continue standard management practices for production.


  1. Trees are to be cut to an appropriate level not to exceed 3 inches. All side branches are to be removed.
  2. Debris is to be processed onsite by chipping, windrowing, and/or burning as deemed legal by the Division of Air Quality.
  3. Offsite processing or disposal costs will not be covered under this BMP.
  4. Re-vegetation with grasses, pines, or hadwoods is required.
  5. Payments will be based on actual costs per acre not to exceed $500.
  6. If a cooperator is going to graze livestock on cost-shared fields, then he/she must provide at his or her own cost livestock exclusion, watering facilities, stream crossing, etc.
  7. The abandoned tree field cannot be replanted into Christmas trees within the maintenance period. The BMP is considered out of compliance if the land use changes (due to the replanted trees or grasses) to another use within the maintenance period.
The following Avery Journal article also has information about this program, "New cost-share program to remove abandoned Fraser fir."

Thursday, February 9, 2012

Working with Safari

With the help of Doug Hundley, I've been following a field treated for elongate hemlock scale at the end of the summer. The grower used Safari + Wisdom (bifenthrin) in early August with a high pressure sprayer. He was trying to get rid of the white from the male scales as well as controlling Cinara aphids on the trees he was harvesting. But he was also hoping to get both good scale control and twig aphid control in the trees that he was leaving. The Wisdom should supply both the Cinara aphid and twig aphid control. The Safari would supply the scale control.

Doug and I have followed the field ever since. Doug was particularly interested in seeing if the white from the male scale would weather away and become less of a problem. So we went in just 3 weeks after application. At that time, the white was already less noticeable, but I found only 55% scale mortality which is, needless to say, practically no control at all.

In mid November, about 100 days after application, we went back and  observed 80% scale mortality. The white from the males was hardly noticeable, and there were no problems with harvesting the trees. Definitely we were headed in the right direction, but the scale control was still not good enough.

Just last week, however, we looked again -- close to 6 months after application. Now the control was around 95%. Control is finally good. This illustrates just how long Safari takes to work.

I plan on looking again at the field in mid-April. Hopefully we'll find that there was twig aphid control from the Wisdom that was applied. Then in June we'll assess how many scales are moving out onto the new growth. If not many are, perhaps the grower can skip scale control for 2012.

The following are some of the questions I'd like to try and answer in 2012:

  1. If you get good scale control one year, can you skip treating the next year?
  2. Can Safari control scales when applied with a mistblower?
  3. What is the best timing and pesticide combinations to control all of our Fraser fir pests including scale?
  4. Can you control theses pests and still have little impact on our natural enemies of scales?

So stay tuned as we try to nail down how to use Safari and other materials to the best advantage. I also have more control results I plan on posting over the next several days. Be sure to attend the NCCTA meeting in Boone on Thursday, March 1 when Doug and I will be joined with Brad Edwards and Brian Davis to discuss getting the most bang from your pesticide buck.

Monday, January 9, 2012

How Do You Know When Scale Control Is Working?

It's not always easy knowing if elongate hemlock scale (EHS) controls are working. On Friday, Meghan Baker and I helped a grower evaluate some Safari and Talstar treatments he'd made in July and August. I collected  shoots to look at under the microscope to determine if the scales were alive or dead. That is the only way to know for sure what kind of control you've gotten. Unfortunately, it takes a lot of work, and few people have access to a microscope.

So how can you tell how well your scale controls are working? Here are some things you can look for several months after treatment. Remember, you won't be able to tell within a few weeks. In fact, all of our treatments can take several months to work.
  1. It's a lot harder to find the scales after treatment. The grower we were working with really knews his fields. He went to several trees that he knew had a lot of scale on them, and had a hard timing finding any. That's a good sign that controls are working. One suggestion is to tag trees with lots of scale prior to treating so you know where to go back to!
  2. There isn't white cotton from the males scales. We were looking on a beautiful day in January. Though the weather was warm, you wouldn't expect to see the white cotton from the male scales yet. That's more of a summer thing. But, if you treated in the spring and were scouting in the summer and didn't see white on the trees, that's a good indication that there has been some control. But, I've seen fields where the control was only marginal where the male production was definitely suppressed. So in my opinion, this is not the best indicator of control.
  3. There aren't crawlers. Crawlers and immature scales are yellow. If you scout several months after application and don't see yellow individuals, then it's a good indication that the treatments have worked. 
  4. There aren't scales on the newest growth. If you treated last year or in the spring, and you don't see any scales forming on the new growth in June or July, that's a really good indication that controls are working . The scales will remain on older growth even if they are dead. Of course some do fall off, but some will remain. So always look at the newest growth to see if there are any scales forming. This is one of the best indicators of control, but you have to wait for it!
  5. The scales look dried up and are falling off. When controls are really good, there is a different appearance to the scales. The males all look dried up, and the females do too. You don't see any yellow immatures. And you can sometimes see on the needle that there used to be a scale present, and there isn't any more. This is a little tricky, because the females scales are brown, and might appear dead. But if you've seen enough treatments, you can develop an eye for what is really dead and what isn't. It helps to train your eye by looking at some of these samples under the microscope.
  6. Looking under the microscope. When I evaluate scale control, I pull 2 or 3 needles off of 6 or 7 different shoots. I try to get some older and some younger needles. I take anything sharp like a pin, and gently prick the very top of the scale. The goal is not to stab the scale and the needle, but to pry off the top of the scales's outer covering to find if the scale is still alive inside. Below are some photos of what to look for.
Obviously, this scale is still very active.
A crawler or any small yellow scales indicates controls didn't work.

Is this female alive or dead?
It is dead because it is empty and dried up inside.
This female is alive, and there are eggs present.
The same photo with everything labeled.
Scales on new growth in June show that treatments didn't work.
The Safari and Talstar treatments made in August gave 99% control. What does that mean? That means that out of 100 or more scales that I examined, only one female was still alive. In actuality, the control is probably even greater because there weren't as many scales as there were prior to treatment.

The grower had some other Safari + Talstar treatments where he used the low rate of Safari (4 ounces per 100 gallons vs. 8 ounces/100 gallons). These were giving 94% control. That means I found 2 or 3 live scales. So should he treat again?

I think I would wait until June to see if scales were showing up on the new growth. If they aren't, I would wait until 2013 to treat again. If they are, he would still have a couple of months to make a treatment in 2012.

This grower also had another scale -- pine needle scale. This scale is much easier to control, and all his treatments worked against it. In the photo below, note some of the scales have holes in the middle, indicating that parasitic wasps have attacked them.

These are all pine needle scale and not elongate hemlock scale.
Assessing EHS control isn't easy. If you need help, contact your local county extension agent and I'll be glad to come out and see. Being patient and waiting until June is probably the easiest way to determine control results.