Pictures of browning needles and adelgids did not tell the full story.

In early April 2023, I received a call from a Partners in Planting program board member I had served with. He was wondering if I would look at some pictures he would text to me. He had a 30-year-old white pine tree in his front yard that had a white fuzzy substance on the underside of the branches. A few branches also had some yellowing needles.

Sensing his concern, I said, “Sure, send me several pictures of the tree. Include the tree at a distance and, of course, the undersides of the branches.” I told him I already had my suspicions, and that the pictures may very well confirm them.

From the photos he texted me, it was evident the tree was infested with white-pine adelgids. I called him back and explained to him that adelgids were rarely a problem for older trees such as his, and that pesticide applications were seldom warranted. I recommended spraying the undersides of the branches with a garden hose using a strong jet-spray nozzle. I also told him the tree could use a little TLC to help reduce any stress factors it might have – mulching and supplemental watering during dry periods.

He was very thankful and sent a donation to Dubuque Trees Forever, since I wouldn’t accept payment for my advice.

Call back

Unfortunately, that friend passed away over the winter. Fast forward to May of this year, when I received a call from his widow asking if I could come and look at the tree. She was very concerned, because one side of the tree was turning yellow and some brown needles were falling off in the wind. I told her I would stop by later that morning.

When I arrived, I indeed noticed her cause for concern. Her description was right on the money and far more troublesome than in the pictures texted to me the previous spring. The adelgid masses were covering the undersides of all the branches. I told her the problem looked much more serious than last year, and that a couple of treatments were available to her through a licensed pesticide applicator who specialized in plant health care. One being a spray application with an insecticidal soap and the other a soil drench with a systemic insecticide called imidacloprid.

Girdling roots were the better indicator. Photos courtesy of the author.

A photo-shy culprit

At the base of the tree was a mixed planting of hosta, bleeding heart, lilies and the like, and if she was concerned about pollinators, the drench would not be recommended. Next, as I was demonstrating how I would go about removing some very old landscape fabric and mulching, I happened to notice a surface root under some pine needles.

This white pine gave no reason to suspect girdling roots. The tree had a nice buttress swell or root flare all around the base, with no flat or concave sides and no going into the ground like a telephone pole. I started to expose the root for its removal, and low and behold, I ran into several more overlapping buttress roots as I made my way around the tree. All but one were beneath the soil line, and none of them were around the trunk itself. Several roots started to inlay and compress buttress-root tissue. Fortunately, the bark was still intact, indicating the cambium was still alive.

The pictures I had been sent from last spring, which included the base of the tree, would never have led me to suspect any kind of girdling, only a significant adelgid infestation. I have learned that you can’t make a complete and accurate diagnosis based upon pictures, no matter how obvious the problem may seem.

Steven F. Pregler is an ISA Certified Arborist and a retired city forester for the city of Dubuque, Iowa.