Algae Control Results

Several people have been concerned about algae again this year. However, I don't think the algae has been as bad this year as last year. In the two fields where we treated, there was definitely more of it on the 2008 growth than the 2009. We had a hot, dry spell in the summer that no doubt reduced the development of algae, but there are still problems. (Photo was taken by Bryan Davis last year showing extreme discoloration in 2009. Note that the current year's needles are not affected).

The first thing to realize when looking at algae control is that the best you can do is prevent more algae from developing. It's hard to cure algae once it's already there. It develops primarily on last year's foliage -- not this year's. It appears that it comes in the June time-frame. Therefore in these spray trials, we were looking at algae development on last year's growth -- that is 2009 growth. For the most part, we didn't do anything to reduce discoloration on 2008 growth (which developed the summer of 2009) or earlier. Still, if you can go to market with 2 years of good green color, it should be good enough.

This photo was taken under a microscope showing some algae on the needles. It is easy to see with a hand lens. It is also easy to wipe off the surface of the needle.

We applied different materials for algae control this spring before bud break at 2 sites -- one in Mitchell and one in Avery. Thanks to Jeff Vance and Jerry Moody for help in finding locations to work in and spraying the materials.

All applications were made with a backpack mistblower. At both sites, an untreated row was left between each treated row to reduce cross contamination of treatments.

At the Mitchell County site, treatments were made on rows of 10 trees. There were 3 replications. Applications were made on April 29 using one of the following materials:

1. Kocide 3000 at 3.5 pound per acre. This is a copper based material which is made up of 30% copper. Kocide label.
2. Dithane at 1.5 pounds per acre. The active ingredient of Dithane is mancozeb. Some Jackson county growers were seeing some control of algae in the fall when this material was applied. However last year, I didn't see very good results from this. Review of last year's work.
3. Daconil at 3 pints per acre. The active ingredient of daconil is chlorothalonil.

In Avery County we didn't replicate, but instead treated a long row with 30 or more trees. Original treatments were made on May 5 using either Kocide, Dithane or Daconil at the treatment rates described above. Addition treatments were as follows:

1. Cosan, an organic disinfectant, at 2 teaspoons per gallon
2. SA-20 disinfectant at 2 teaspoons per gallon. This product is made of 10% dimethyl benzylammonium chloride and 10% dimethyl ethybenzyl ammonium chloride. It is used to disinfect pots, greenhouse areas and tools.
3. Kocide applied twice -- on May 5 and again on May 19
4. Kocide applied once on May 19

Jerry, Doug Hundley and I looked at the Avery County treatments yesterday, and Jeff Vance and I looked at the Mitchell County treatments this morning.

There appeared to be more algae developed at the Avery than the Mitchell County site. This surprised me as the Mitchell County site was much worse last year. (This photo, taken in Mitchell County, shows a shoot from an untreated tree with algae on last year's growth).

All treatments appeared to have some effect on the algae. The Dithane and Daconil didn't work as well as the other products. Kocide appeared to work best. Applying it twice seemed to work a bit better, and applying it later in May also seemed to work some better.

This photo is of a shoot from a treated tree. Note that there is no discoloration on 2010 or 2009 growth. If the treatment hadn't worked, you would see discoloration on 2009 growth. The material didn't reduce the discoloration already present on 2008 growth. 

This is typical of any fungicide. They prevent disease from developing. They don't cure disease. Therefore a successful treatment will keep algae from developing the year it is applied. But that's similar to all of our pests. When you treat for twig aphids or spider mites, you don't do away with the damage you already have. Instead you cover it up with new, undamaged foliage.

I would like to repeat this next year, applying materials with either a high pressure sprayer or backpack mistblower. I suspect that the high pressure sprayer will give better control, but that most growers will prefer the speed of the mistblower. I also hope to try out some Kocide this fall to see if it will help "cure" some of the algae. I don't think it will, but since I didn't try it last year, I want to make sure. 

Take home message: It looks as if Kocide and perhaps some other materials will reduce and in some instances prevent algae from developing when applied in the spring. In fields where algae development is expected because of woods or the trees are growing close together, a preventative treatment is required starting the year before sale and continuing until all the trees are harvested.

A big thanks goes to Kelly Ivors and Gary Chastagner for their help in identifying possible treatment windows and materials.

Some HWA Pics

OK, I know this is a Fraser fir IPM blog. But I work some with HWA on hemlocks and can't help but post a few things about that too.

Five years ago, I took some photos of hemlocks in the Linville area. Today I went back and visited some of those trees. Mostly the hedges looked really good. But many of the trees that I know had been treated are now gone. Others don't look much better.

Here are the pictures:

This picture was taken five years ago.

This is the same tree five years later. It is still hanging on, but doesn't look much better.

This tree is no longer there. It had been treated with Merit, but didn't seem to be doing too well five years ago when this picture was taken.

These trees are in the same yard as the previous picture. They don't look that good either, but are at least still alive. The hedge, however, looks great.

My last photo is dead hemlocks along the Parkway.

2010 Growth in Organic Demonstration.

Today I measured the terminal growth on the 183 trees I've been evaluating at the organic demonstration in Alleghany County. Thanks again to Della and all the Deals and Tuckers for all their help with this study.

A big thanks also goes to Bryan Davis who has been keeping the site going. For the 3rd NCTA farm tour on August 14, Bryan dug up three trees from this demonstration so that folks could see how the trees were doing. One was a typical "late organic." Remember that these are the trees that are being grown conventionally until the last 3 years before harvest when they will go totally organic -- that is, they are "going organic" late in the rotation with just enough time to be certified as organic. He also brought 2 trees from the organic portion -- one that was growing poorly and one that was growing well.

Those trees were strikingly different. The poor organic tree was just barely alive. The good growing organic tree was growing well, until you compared it to the typical "late organic" tree which was taller and fuller.

The numbers I collected today with the help of my daughter (in the rain no less) bare this out. I measured the terminal of the trees and also gave the trees a rating based on how well they were growing. Trees were given a rating of "1" if they were barely growing at all. A "2" rating was given to a tree that was growing better, but still had poor color and bud set. A "3" rating was given to a tree that was growing acceptably. A "4" rating was given to an exception tree both in color, bud set, needle length and fullness. Of course these ratings were completely subjective and sometimes I had trouble deciding between a "2" and a "3" or a "3" and a "4."

Here is a summary of the data. The "late organic" trees are more likely to have a rating of 3 or 4. Their terminal growth is on average 4.6 inches longer, and there is a higher percentage of trees with at least 12 inch terminals.

There are some very nice looking organic trees. There just aren't as many as in the other section. Still, all the trees are growing better than they did last year. Last year the average terminal growth for the entire study was 6.1 inches. This year it was 14.0 inches -- more than twice as much. The trees that suffered severe drought when they were planted in 2008 with a southern exposure are finally growing strong.

NCTA Meeting

Hope everyone can come to the National Christmas Tree Association annual meeting in Winston this week.

I will be speaking on Friday morning. My talk is called, "Getting Personal With Pests." We have it on-line if you'd like to look at it. It is found at: http://www.ces.ncsu.edu/fletcher/programs/xmas/production-mountains/Sidebottom-Pests_2010-08-13.pdf

It's kind of a big file, so it will take awhile to pull up.

I'll also be on two of the farm tours. I'll be speaking on Saturday morning at Harry Yates' farm on elongate hemlock scale. Then in the afternoon I'll be speaking at Omni farm on scouting, pest control and our organic demonstration.