Additional Cowles Article

Dr. Cowles sent me another article for everyone to review. It is called, "Optimizing a Basal Bark Spray of Dinotefuran to Manage Armored Scales in Christmas Tree Plantations." Click on this link (the name of the article) to view this pdf file. Be patient, it takes a few moments for it to become clear on your screen.

Visiting Scientist Richard Cowles

On Friday March 4, Dr. Richard Cowles with the Connecticut Agricultural Experiment Station will be speaking about scale control in Christmas trees.He is an expert on scale control, working with both elongate hemlock scale and Cryptomeria scale. He also has worked with the systemic insecticides such as Merit and Safari for hemlock woolly adelgid control. Attending the NCCTA meeting would be a great opportunity to learn from and talk to this expert.

The following are two references by Dr. Cowles that you might want to look at before the meeting.

1. 2008 Scale Efficacy Trial: In this paper is information about Judo, Onyx, Botaniguard and Safari for elongate scale control
2. Connecticut Weekly Agricultural Report, April 7, 2010: A New Method for Managing Armored Scales in Christmas Tree Plantations: This report has information about trunk applications of Safari for scale control in Christmas trees

Pesticide Safety Web Site

Farm safety is a big topic these days. As stated on the OSHA homepage for agricultural operations, “Agriculture is one of the most hazardous industries in the nation. Farming is one of the few industries in which the families (who often share the work and live on the premises) are also at risk for fatal and nonfatal injuries.” These dangers are compounded when most farmworkers are Latino, and even Spanish may be their second language. Their understanding of English is often limited, making them an especially vulnerable work force.


To help growers comply with existing laws, and to draw together resources from many states, a Christmas tree farm safety web site has been developed. 


Information is organized in several categories including general farm safety, equipment safety, shearing safety, pesticide safety (by far the biggest section), and harvest safety. Many resources are available in Spanish. There are links to pertinent laws, laws for record keeping, forms to record worker training, and videos on many topics.

So check it out at: www.ces.ncsu.edu/Christmastrees/farm-safety

How Things Have Changed

I found an important photograph quite by accident about a week ago. It was on a postcard in The Muses bookstore in Morganton. The photographer is Christopher Smith (www.christophoto.com), who is in Asheville and specializes in weddings and landscapes. I contacted Mr. Smith and he graciously allowed me to use his sopyrighted photo in my blog and my talks on hemlock woolly adelgid.

Why the interest in his photo? It was taken in 2001 at Linville Falls. His photo clearly shows the hemlocks growing in the spring against the dark shadow (note the magnolia blooming). This was before the HWA had made an impact. I didn't have a photo from this time, and even if I didn't, it wouldn't have been that good. You can compare it to my own photograph which I took on Labor Day 2010. The difference? A picture is worth a thousand words, and words can't describe the irreplaceable loss this pest has made in western NC and elsewhere along the east coast.

Chris Smith photo, 2001

My photo, 2010

Needle Drop in Scale Infested Trees

This week I finished taking data on the needle drop in cut branches from scale infested trees. I reported on the experiment on November 10th when I set it up. The experiment worked worked well in that there was needle drop, but since there was too much needle drop, I guess it worked a little too well!

Many of the needles shattered as depicted in the photograph to the left. On some branches, almost all the needles fell off. That is definitely not something we're used to seeing with Fraser fir. If you look closely at this photo, you can see that this was from a scale infested tree, but the uninfested trees were just as likely to shatter -- just not as badly.

The room that the branches were stored in was very hot. It's an unused room at the Mountain Horticultural Crops Research Station office, and both Jeff Owen and I had shoots stored there. They kept the door shut and the room, which faces the sun, would often be too hot to be comfortable in. The shoots in the buckets faired the worse, dropping many needles. The shoots that were were kept dry kept almost all of their needles to the end of the study, but they dried out and became very brittle.

So did scale infested trees drop their needles more than uninfested trees? The quick answer is, "Yes." The results are summarized in the following table which lists the average percentage needle drop for all 15 trees in each group (infested and uninfested) for both the trees stored with water (wet) and without (dry). On average, 43.1% of the needles on scale infested branches had shed their needles while only 27.8% of needles on uninfested branches had shed. Also note in the table that there was more needle drop in the field on scale infested trees (first column labeled "From Field"). I had reported this back in November.

If you look at individual trees, by the end the experiment 47% of the infested branches in water had shattered a third or more of their needles (much like the photo above) while only 27% of the uninfested branches had more than 1/3 needle drop. Of course, that is much more needle drop than would be expected from cut Fraser fir. Remember that these branches spent less than 24 hours without water. Needle shed should have been at a minimum, and was through the first couple of weeks. Only one tree shattered its needles in week 2, and that was a scale infested tree. But by week 4, there were needles everywhere.

If you are a very perceptive observer, you will also note in the table that I only report on 1st and 2nd year needle drop and not 3rd as I said I would do back in November. That is because some of the 3rd year needles were under water in the bucket, and I didn't trust the results from them. In this photo, taken in week 2, the discolored needles had been underwater. These were more likely to fall off.

Generally results were along the lines I anticipated -- more needle shed in scale infested trees -- but the data were far from pretty. After all, there were uninfested branches that totally shattered their needles, and there were scale infested branches with very little needle shed. There were trees where one branch placed in water shed their needles, and the other branch from the same tree also in water hardly did at all. On about half of the scale infested trees, of the two branches taken, the one with more scale had less needle drop. So, I am not real happy with the results. I think I'll repeat this experiment next year either in January or next harvest season to see if I can get some clearer results.

I do think I can safely say the following: there appears to be slightly more needle drop in infested trees. However, needle drop occurs for a variety of reasons, and scale infestation is definitely not the over-riding factor. Still scale infested trees are messy. The scales themselves drop off as the tree dries out. There also appeared to be some fungi growing on older scales as my last picture shows.

This quick little study just confirms what many people had been telling me, that scale infestation doesn't help the quality of cut trees.

Updated Results on Scale Control

I reported in July on some control results of scale treatments I had made on June 20. To recap, I used a backpack mistblower at Dale Cornett's in Watauga County. I used either Asana + Dimethoate, Lorsban, Movento or Safari. In July I went back and the Safari and Asana + Dimethate both gave control, but only about 85% control. This was a bit disappointing. The other two didn't work, but then Movento is a systemic and slow acting, so I vowed to return and see if time would improve the results.

I went back today and now the Dimethoate + Asana and the Safari both had 100% control. I did not see any live scales at all. It was hard to find shoots that had scales on them, and they all looked dried up just by looking at the shoots. There was no white cotton at all.

The Lorsban and Movento treatments were still similar to the untreated check trees. They still hadn't worked.

So not only did control improve with the Safari, it did with the Dimethoate + Asana as well. Maybe we go back too quickly to evaluate control. These materials apparently keep on working.

Remember that currently Safari does not have a Christmas tree label -- only a nursery label. So if you aren't digging your Fraser fir, you're not supposed to use it. Hopefully that will change next year. These results are certainly encouraging.

Research out of Connecticut has indicated that Safari will controls scales with a trunk application, at a reduced rate per acre. These treatments can be made in April through June. I plan on trying this next year.

Scales & Needle Drop

Why does Meghan Baker, Watauga County Extension Agent look so happy? We were done collecting shoots! Meghan helped me on Monday collect shoots from a grower's field to help determine if elongate hemlock scale infested trees are more likely to drop their needles after the tree is cut. Several growers and Christmas tree retailers have told me they think scale infested trees are more likely to drop their needles. Other pests such as spider mites and balsam woolly adelgid cause similar problems. Hopefully we'll soon know if it's true of elongate hemlock scale as well.

Meghan and I collected shoots off of 15 infested and 15 uninfested trees. We took three years worth of growth plus a little bit of the fourth year branch in order to stick the shoot in our trays. Since scale goes back multiple years, we wanted to see how it was affected older needles.

Our samples were paired. We took two branches from one area on the tree and another set of two branches from another area, usually on the opposite side of the tree. One of the paired branches will stay in the bucket with water. The other one goes in a tray without water. Having two sets of these pairs will allow us to compare results within a given tree. Needle retention varies greatly between trees even without pest infestation. It can also vary with different positions on a tree. Most of our samples came about 1/2 way up the tree and some branches I cut were practically against the trunk.

This is what all 120 shoots look like today. Each branch is labelled so I can keep track of what tree they came from. Half of the branches are in buckets of water and half in styrofoam trays without water. Yesterday I took data on the scale infested branches, estimating the percentage of needles with scale on the 1st, 2nd, and 3rd year growth. Infestation varied widely. I have some branches with 2nd and 3rd year needles having 100% infestation, and others with less than 25%. I also marked if there were other problems with the foliage such as twig aphid damage or small, yellowed needles that are also more likely to shed. If there was any needle drop already, I also made note of that.

In a week I will take each branch and lightly rub my hand over the foliage and estimate the percentage of needles that fall off, again keeping track if they are from the 1st, 2nd, or 3rd year shoots. I'll take ratings again after 2 weeks, and final data after 4 weeks. Already I'm finding that the 3rd year needles of heavily infested trees were falling off the trees in the field. These trees are such heavy density so it probably wouldn't have mattered, but if they keep coming off in the home, it will cause a mess.

I want to give special thanks to Jeff Owen who has conducted several experiments like this looking at other factors affecting needle drop. He was able to help me with the experimental design. Much of this type of research was originally conducted by Drs. Eric Hinesley and Gary Chastagner. And of course thanks to Meghan for her help, and for the grower, Johnny Greer, who donated his trees. Also a big thanks to the Mountain Horticultural Crops Research Station at Mills River who are donating some space in a spare room to mimic someone's home. (I promise to sweep up all the needles!)

I'll let you know how it all turns out.