Some Results on Pest Control

We're seeing more twig aphid damage than I anticipated. After all, it wasn't easy to find twig aphids in April. Plus we had lots of rain and cooler temperatures which tend to reduce the survival of the aphids. But they are well adapted to western NC, and they have ended up causing some damage.

BUT... with all the rain, a lot of the damage is disappearing. I spoke with Bryan Davis who told me that he is seeing less needle curl in fields this week even than last week. Thanks to the rain, the majority of this curl will go away.

This leads me to some data to report from my current studies.

FALL TWIG APHID CONTROL: Last fall, Jerry Moody and I treated some trees October 18, 2010. Really we were trying to see how late you could treat in the fall and still control elongate hemlock scale. But I also wanted to see if the treatments would control twig aphids the following spring. We tried Safari (applied to the foliage with a high pressure sprayer at 8 oz/100 gallons), Lorsban, and the standard Dimethoate + Asana.

I did evaluate scale control this spring, and none of the products worked well. This wasn't surprising as mid October is probably too late to get much scale control. However, I also evaluated BTA control this spring with these fall treatments and those results are pictured here.

Remember that I evaluate twig aphid damage by either walking around the entire tree (which makes me dizzy!) or working with a partner. For these observations, I worked with Jerry Moody. We walked on either side of the tree and estimated the percentage of 2011 new shoots with needle curl each on our respective side -- then we come to an average figure for that tree. These result in the numbers in the first column (% shoots with curl) -- averaged for all 20 trees. The next column has the percentage of the 20 trees with at least SOME needle curl. The third column has the percentage of 20 trees with 10 % or more of the needles curled. This is the point where most growers tell me the damage is bad enough to affect the value of the tree. Of course remember that the needle curl will decline over the next several weeks, so all of these numbers will go down. Still, the comparison now when the damage is at its greatest tells us how well the products are working.

Obviously, neither the Lorsban nor the Safari are giving us any twig aphid control when applied in the fall. The Asana + Dimethoate worked well, though not perfectly. In fact, Brad Edward's observation this spring has been that the Asana in the fall isn't working quite as well as the Talstar applied in the fall. It works, but a bit of curl gets through. These results bear this observation out, and in fact the first year I did this type of work at Omni Farms, that was our observation. Still, the Asana + Dimethoate gives good enough control and it would be more effective against scales.

SPRING CONTROL WITH SYSTEMICS: So how well does Safari and Movento work in the spring? Jerry and I applied these products at two farms, treating on April 18, 2011. In this instance we applied the Safari to the base of the tree trunk and not the foliage, using a rate of 1 pound per acre. At two farms we did this with a high pressure sprayer, and at one farm just with a backpack sprayer. The Movento and bifenthrin are applied with a high pressure sprayer to the foliage.

The results again demonstrate that Safari isn't giving us twig aphid control. Practically all the trees had some needle curl when treated with Safari. The Movento gives fair control. A lot of trees have some curl, but hardly enough to worry about. The bifenthrin is of course the best.

At these two farms there was also scale and woolly adelgid. We will be looking at the control of these pests later on in the summer, so stay tuned!

OTHER OBSERVATIONS THIS SPRING: Once again, several people I've spoken with this week are commenting on spider mite activity. The rain is reducing mites to some extent -- probably by increasing predator mite activity, but it is still important to scout for spider mites and make sure they don't damage new growth. The good news? All of this hot weather should be taking care of any rust mite issues!

Ways to Put Out Safari

On Friday, Jeff Vance and I tried putting out Safari in some Christmas trees. We used either a backpack sprayer with a hollow cone nozzle, or a high pressure sprayer. With either sprayer, we were targeting the lower 10 inches of the trunk.

Unfortunately, I think the application was uneven. On some trees, there was good coverage all around the trunk. This is important because only when the entire trunk is encircled with spray will the entire tree get a dose of the chemical. But on other trees, the entire trunk was not completely covered.

Jerry Moody also tried applying Safari to his trees. In his case, he targeted the entire trunk of the tree, treating from both sides, and not just the base. He ended up using more water but he made a more dilute spray to target 1 pound of Safari per acre. And he thought he was getting excellent coverage, as well as moving quickly through the trees.

Next month when Jeff and I spray, I think we will compare different application methods of Safari using a high pressure sprayer -- treating just the bottom 10 inches, treating the entire trunk, and treating all the foliage lightly -- like a balsam twig aphid spray. That way we can find the quickest, easiest method of application. We hope to have this field on the NCCTA summer tour next year in 2012.

Getting the Most out of Safari

On Monday and Tuesday I was applying the active ingredient, dinotefuran (aka Safari), to hemlock trees for hemlock woolly adelgid control. Learning how well this works should help with elongate hemlock scale control in Fraser fir, so even though this project isn't related to Christmas trees, I think it's still important.

The label for the trunk application with Safari has a range of rates from 12 to 24 ounces per gallon. However, in other literature that the chemical company, Valent, puts out, it says just to use the 12 ounces per gallon rate, so that is what I did on Monday when I treated hemlocks by myself at a site in McDowell and on Tuesday when I worked with NC Forest Service folks, Brian Heath and Craig Lawings treating trees at the Crossnore Nursery in Avery County.

The label also says that one gallon should treat about 40-50 inches cumulative trunk diameter. Therefore, one quart would treat a 10-inch diameter tree. However, it also says to treat until run-off. When I applied the product on Monday, I was treating until run-off and ended up treating about 100 cumulative inch trunk diameter -- or twice as much. We'll see if well it works. On Tuesday we tried to stick to one gallon treating 40 inches. The first thing we did was calibrate to see how long it took to spray out an ounce. This photo shows Craig spraying and Brian keeping track of time.

With the sprayer he had, it took about 9 seconds to spray out an ounce. Therefore on most trees we treated, Craig sprayed between 2-4 minutes on a single tree trunk. This photo is a close-up of the bark of a good sized tree after treatment. You can see the foamy bubbles of the chemical on the trunk.

You are supposed to treat all the trunk including the root flares to about 5 foot. This photo shows a tree trunk after treatment. These trees were previously measured and marked by Brian and Craig -- you can see the metal tag on this tree with the identification number.

One question we had was if the chemical would be taken up well by trees with a lot of lichen as is shown in this photo. We tried to make note of trees with exceptional amounts of lichen so we can follow them over the coming months.

Here is a photo of Craig spraying as well as a video. Many of these trees are right on the Linville River. This is a recommended treatment for trees near surface water as you are just spraying the trunk of the tree and not the soil.

A link to Joe Chamberlin from Valent applying the trunk application is found here. The video is on YouTube and is for emerald ashe borer, but it is the same basic method.

Many of the trees we treated on Tuesday were hard to get to. Brian had to get out a machete and hack a path to the tree then hack around the tree so Craig could get to it with his sprayer. That's why it's a new kind of hack and squirt!

These trees aren't doing well. We'll see if the material can bring them back. This photo shows the state of some of the trees as seen from the highway.

We did more than 30 trees on Tuesday. Brian and Craig will end up treating more than 70 trees this spring. That will give us a percentage of how successful we end up being! The trees I treated on Monday are in a bit better shape. This photo shows some of them taken last summer. But then I also used about 1/2 the recommended rate, so that will also be interesting to follow. I treated close to 30 trees on Monday.

As usual, I will post additional results and observations as they become available.

MITES!!!

I'm surprised how many spruce spider mites I'm seeing this spring, considering how wet it's been. I have been in several fields where individual trees were absolutely cover in mites.

This terminal is covered up in spider mites and their eggs. There is even some webbing between the needles which is where spider mites got their name.

This shot shows my fingers after handling the mite covered terminal. This is the color of squished mites!

These trees were at the site of our organic study. I think I will treat them all sometime in the next few weeks. What's complicating this is that the new growth is out. I'm afraid I'll burn them which is why I'm going to hold off a few weeks.

The final shot I'm posting today shows the difference in the ground covers between the organically grown trees, which are full of grass, and the "late" organic trees that are still being grown conventionally with Roundup use. We will switch to organic production the last three years before sale.

The organic is in the background, and that's where Brad's mowing. In the foreground are the "late" organic, which haven't been treated yet with Roundup. There were areas of the field where the clover was keeping out any weed problems. There appears to be much more biodiversity with the use of Roundup. Hopefully this summer I can get some data along these lines. But for right now, a picture is worth a thousand words!

Ready Or Not!

I saw my first Fraser fir with buds breaking yesterday. So ready or not, it's spring!

The weather hasn't cooperated much in getting spring pesticides out. If you got behind and buds are breaking and you need to control twig aphids, an application of Dimethoate should control the aphids even in the broken buds. This will also knock back spider mites and rust mites. This works best when applied with a high pressure sprayer -- not with a lot of pressure, but with good coverage of all the new growth. However, even with a mistblower, it still may help.

So far this spring, though, I haven't seen many fields with enough twig aphids to worry about. With all the rain we're getting, it will greatly lessen the impact of twig aphid damage and spider mites as well.

The key is to not forget the spider mites as the summer progresses and especially if the rains stop. Late season spider mites can sneak up on you. Even if you use a good miticide in the spring, that is no guarantee that spider mites won't become a problem again by late summer or fall. Even a quick job scouting is better than not looking at all.

I guess the point of this post is to not worry if you haven't gotten all the insecticides you intended to before bud break. It is better to not apply a pesticide than to put it out in poor conditions such as too windy or rain on the way. Just keep an eye out for developing problems. Nine times out of ten, pests like twig aphids and mites won't be bad enough to worry about.

Honoring John Fraser

Today marks the 200th anniversary of the death of John Fraser, the man for whom the Fraser fir is named.

I hope you were able to read the article I wrote for LIMBS&NEEDLES about John Fraser. He was a remarkable man, exploring this country and its rich plant life when it was nothing but wilderness.

He wasn't the exacting botanist that Michaux and others were. He didn't leave any notes. Some said that he  explored and collected solely for financial gain, and for that reason should be looked down on. But in my opinion, he found a way to make a living doing what he loved. Like the Fraser fir which tenaciously survived on the highest mountains following the last glaciers, John Fraser didn't require anyone's approval. He was self taught, self motivated, and carved out his own name and niche. His legacy is the perfect symbol for the North Carolina Christmas tree growers that followed him scores of years later, who were also self taught, self motivated, and carved out an industry where people said it couldn't be done. Now the Fraser fir is recognized all around the world as one of this planet's best Christmas trees, and it still proudly bears the name of the man who first brought it down off the mountain.

So thank you, John Fraser. Your tree is still well loved and we trust it will be well into the future.

Pest Problems Caused by Economics

With problems in selling trees come increased problems with pests. As trees keep getting larger and start growing into each other there is more opportunity for algae and other pest problems. These are related to the lack of air movement around the trees.

In a field I visited today there were actually 3 problems causing discoloration of the foliage -- algae, elongate hemlock scale, and a disease called Rosellinia.The fungus grows in the interior needles, causing them to shed. The fungus grows in mats and produces the fungal spores pictured here.

The remedy for Rosellinia fungus and algae is to improve the air movement by keeping weeds in check, butt pruning trees, and removing trees that are growing into each other.

You can also control algae from developing in the foliage that was produced last year by spraying right at or just after bud break with the copper based fungicide Kocide. For information on algae control check out past entries on algae.