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)."

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."