Algea

We had more growers with algea problems last year than ever before. We tried various products in the fall to get rid of the discoloration including Prev-Am, chlorox solutions, Dithane, horticultural oil, or zerotol. I even tried painting some trees. But nothing seemed to work.

That's when Kelly Ivors, our plant pathologist, talked with Gary Chastagner about it. They have been using copper based products in the spring out west to prevent algea from appearing.

So this week I hope to put out two studies looking at algea control -- one in Mitchell County with the help of Jeff Vance and one in Avery County with the help of Jerry Moody. We are going to be applying fungicides with a backpack sprayer. We'll treat some trees only once. Other's we'll retreat in about two weeks.

One of the products we're using is particularly recommended by Chastagner, called Kocide. The active ingredient is copper hydroxide. Kocide 3000 is labeled for fir trees in Christmas tree plantations to control needle casts at the rate of 0.75 to 1.75 pounds per acre and to control lichens at the rate of 3.5 pounds per acre. It should be applied before bud break.

I don't know yet if it will work, but it is a labeled product that you can try if you had a serious problem last year and think you'll have a problem again this year. I would only recommend this treatment in fields that are humid, such as those near woods, creeks, or where the trees are getting large and growing together. The label can be found at:http://www2.dupont.com/Production_Agriculture/en_US/label_msds_info/labels/SL-1344-2.pdf

Earth Day

For Christmas tree growers, every day is Earth Day. Since I started working with Christmas trees in 1988, I've seen a complete transformation of the industry in North Carolina. Growers have slashed their pesticide and fertilizer needs through adoption of IPM practices and good ground cover management.

And look at the healthy Frasers on Mount Mitchell. I took this photo last year from the new tower. Given half a chance, nature has a wonderful ability to heal herself.

Getting Rates Right

I don't think there's anything else that causes people more confusion than numbers. And unfortunately, pesticide rates are all about numbers.

Insecticides can be labeled as a per acre rate, or a per 100 gallons rate. Growers like the 100 gallon rates, because they are easy to mix, but often the per acre rates are more accurate.

When spraying with a mistblower, it's pretty easy to calibrate the sprayer. In fact, most growers can tell you exactly how much water they are putting out per acre. The problem comes when putting out sprays with a high pressure sprayer. Yet, when I start to question people, they can usually give me a ball park figure -- say less than 200 gallons per acre or around 300 gallons per acre or 500+ gallons per acre. And that's all you need to know to get an idea of how much chemical to add per 100 gallons.

For instance, if you are trying to apply Envidor at 24 ounces per acre, it you are using 300 gallons of water per acre, mixing the product at 8 ounces per 100 gallons will give you the exact rate. But if you are spraying 500 gallons of water per acre, you will be applying more than 40 ounces per acre which exceeds the rate and will cost way too much money. If you're using less than 200 gallons of water per acre, you'd best mix it at 12 ounces per 100 gallons. So before you mix, think about how much water you're likely to use. *(See below for calibrating a high pressure sprayer).

Using that same Envidor at 24 ounces per acre out of a mistblower? Applying 40 gallons of water per acre? Then you would mix the Envidor at 60 ounces in 100 gallons.

But what about when you are applying a materials with a mistblower that has a per 100 gallon rate? Asana is a good example of this. Labeled at 9.6 ounces per 100 gallons, it can be used in a mistblower to get control of multiple pests including twig aphids, balsam woolly adelgid, and elongate hemlock scale.

Back when I first started working, Bill Huxster and Jim McGraw encouraged people to use 3 times the per 100 gallon rate when spraying with a mistblower. That's because growers are using much less water, but they still need basically the same amount of chemical per acre. It turns out, that's a pretty good rule of thumb. A mix of 30 ounces of Asana per 100 gallons seems like a lot, but Asana is labeled at up to 52 ounces per 100 gallons in ultra-low volume sprays (such as an aircraft) and as much as 37 ounces per acre for certain pests in Christmas trees.

When looking at labels, see if there is a cap for application. Is there an amount you should not exceed when applying materials specified on the label? Use this as your guideline for how much to apply.

Figuring out rates when it comes to insecticides is just common sense. Take a minute to make sure what you're using makes sense.

*CALIBRATING A HIGH PRESSURE SPRAYER:You can always calibrate your high pressure sprayer. First determine how much water you are putting out per second. Spray into a bucket for 10 seconds having set up the gun the way you mean to spray, measure what you spray and divide by 10. (You might need to cover the bucket with a garbage bag to keep it from coming out). That gives you what you are spraying out per second. Then spray a few trees and see approximately how many seconds it takes to cover the tree the way you want to. 

An example -- say you spray 3 ounces per second and approximately 4 seconds per tree on one side. Since you spray from two directions, thats 8 seconds per tree. That's 24 ounces of water per tree. If you have 1,700 trees per acre, you are using about 300 gallons per acre. If you stock at 2,200 trees per acre, you would be using about 400 gallons per acre.

Twig Aphids Reproducing

Just wanted to let everyone know that I examined some shoots under the microscope today and found evidence that the twig aphids have matured enough to being reproducing. Remember that the form that hatches from the egg is called the stem mother. At maturity she lays live young. That is taking place now.

With this warm dry spring, twig aphids are surviving well and maturing quickly. There is a potential for damaging numbers to build up quickly now.

Role of Apollo

Several folks have been talking about treating this spring with Apollo plus Dimethoate. Apollo is a miticide with similar activity to Savey. Those Apollo plus Dimethoate should give good control of twig aphids and spider mites, but only fair control of rust mites. After all Apollo, though an ovicide, has no activity against rust mites, just as Savey doesn't.

The kicker is, there are almost no spider mites anywhere. I've worked  tree fields for several weeks, Bryan Davis has, and several other agents. Fields with spider mites are few and far between. I think I've seen a dozen spider mites eggs total in 3 weeks of scouting.

Rust mites, however, are being found frequently. A few fields have high rust mite numbers. Other just have maybe a mite per shoot. (Remember that the treatment threshold is 80% incidence and at least 8 mites per needle).

The mix of Apollo + Dimethoate will knock rust mites down (due to the Dimethoate), but since it is so early in the season, the mites may rebound. That is why in a situation where rust mites are plentiful now, Envidor is the better choice. It controls both spider mites and rust mites. Envidor plus Dimethoate should give excellent and full season control of twig aphids, rust mites and spider mites.

Scouting will determine which blocks should have the Envidor added, and which don't, as rust mites are not a problem in every farm or even on every block on a farm. Don't assume that just because you used either Asana or Talstar last fall that rust mites are a problem. They aren't. You don't know until you go out and look.

And scouting doesn't have to take a lot of time. When I go out with the county agent or technician, it always takes longer because we're talking about control options, showing the grower different pests and the like. But if I was just going out there to scout, it wouldn't take me long at all.

Envidor is only labeled to be applied once per year (as is Savey and I think Apollo as well). This is to reduce the likelihood of resistance. But chances are, spider mites won't develop and become a problem if you have good ground covers. Even during droughty years, we've seen very few farms with bad spider mites in recent years. Once again, a quick scout through should be able to identify problem sites.

So scout. Then chose what you need based on those scouting results.

Controlling elongate hemlock scale (and everything else too!)

This is a picture of a Fraser fir heavily infested with elongate hemlock scale (EHS). We're starting to see more symptomatic trees like this in the area and frankly more problems with scales.

Bryan Davis and I have been working with a grower in Ashe County who treated multiple fields in 2009 with Dimethoate + Asana using a high pressure spraying for scale, starting June 26th and going all the way through September 7. Most of these fields had a very heavy incidence of scale.

What we're finding so far is that the fields treated in June and July and into the first 2 weeks of August had decent control -- mostly 90% or better. By later in August and into September, control really dropped off -- to about 70%.

Of the 8 or so fields we've looked at so far, all appear to have twig aphid control and only one had a heavy incidence of hemlock rust mites. The grower didn't use any Envidor. In the bigger sized trees, we'll go back and check on twig aphid control again, but hopefully it will be sufficient. In one spot where there had been balsam woolly adelgid, it had also been controlled.

At a meeting I had last night in Watauga County (which is sort of EHS central!), a grower shared that in a block of trees where he's had to treat for rosette bud mite, spraying Dimethoate by itself in June, he's had no EHS, even though there is plenty of scale all around him.

So, should we even be treating earlier for EHS? In June perhaps?

ALERT: Also wanted to let everyone know that a new scale which they are having problems with up north in Frasers and other firs -- Cryptomeria scale -- was identified last week in Macon County. It was the first reported incidence in North Carolina.

Scales are definitely becoming more of a problem. Is it the loss of Lindane? Warmer winters? More use of synthetic pyrethroids and Thionex? One thing's for sure, they will make international marketing a lot tougher, as the presence of most of these scales will stop sales.

Twig Aphids

SUMMARY: Twig aphid hatch is at about 86%.

Jerry Moody and I applied Movento with different adjuvants today. Remember that Movonto is the systemic that needs a good penetrant to get into the foliage. The problem is that several we used last year caused needle burn. Also, we didn't get great twig aphid control because we didn't put it out early enough.

Well, we got it out early enough this year! We tried Movento at the full 10 oz/acre rate either alone or with the following adjuvants: horticultural oil, Eco-Tec, ammonium sulfate, NIS (80/20), Liberate, or Phase.

I checked the twig aphid population at the field site, and there were plenty of aphids -- approximately 1.4 eggs per shoot. I estimated that there was about 86% hatch. There are several 2nd instar aphids. So, you can start scouting for twig aphids now, and certainly by next Monday, you can easily scout for twig aphids.

I think we put in a good study. I'll let you know the results come mid-May.

End of March Assessments

I've had the opportunity to walk through several Christmas tree fields the last couple of weeks. Here are some of my observations.

BALSAM TWIG APHIDS: I'm still not seeing many fields that have high twig aphid numbers. I finally found a couple that did, but mostly there aren't many aphid eggs. Bryan and I found our first live twig aphid on March 30! It was tiny -- just a fist instar. The weather during April will determine how bad twig aphids end up being. Now we're having warm, dry weather which will allow the aphids to quickly hatch, mature, and start to reproduce -- laying live young. If this kind of weather keeps up, those few aphid eggs will turn into plenty of aphids to curl needles by bud break.

We were in one field that had been treated with Talstar in the fall, that actually had a dead aphid sticking out of the aphid egg. But it's still a bit early to be evaluating how these fall aphid treatments are working. Wait until April 15, and then it should be easy to beat aphids out of trees if they are present.

However, if you didn't treat in the fall, and you need to control twig aphids, don't wait until the 15th unless you are using either Di-Syston or Thionex. All other materials including Asana, Talstar (Wisdom), and Dimethoate can be applied now.

BALSAM WOOLLY ADELGID: I visited another field yesterday where several trees were showing symptoms of woollies (flat tops, swollen buds, stiff trunks), but it was extremely hard to find any live woolly on the trees. What we did find were on the buds, and we had to look at lots of buds before we found them. These trees had been completely untreated in 2009. Therefore, I think we're seeing quite a bit of winter kill of BWA, but don't assume they are all killed out. Fields with symptoms of woollies should still be treated for them.

SPRUCE SPIDER MITES: I have yet to find a field with more than just a few spider mite eggs this spring. I'm sure they are out there, but for now, I don't think there are many growers that will have to worry about this pest.

HEMLOCK RUST MITES: Rust mites are really active this spring -- much more so than in the last couple of years. We walked through several fields last week that had been treated in July or August with Dimethoate + Asana to control elongate hemlock scale. This is a combination that should create rust mite problems the following spring, but of the four fields we visited, only one had rust mites. The other fields had virtually no mites.

We walked through another farm this week that had been treated with Talstar in October. It was a very large farm that rambled up and over a ridge, dropping down to the river. On the ridge top, the rust mites were nearing treatment threshold. In other areas of the farm, there weren't any.

So what's a grower to do??? SCOUT!!!! You can find the blocks that need rust mite controls and target only those for treatment. It doesn't take a lot of time to scout. A field of several acres can be evaluated in just 30 minutes. That's worth knowing where you need and don't need rust mite control.

Envidor will provide longer lasting control than just dimethoate. After all, it's a long time until summer. Spring's barely started.