Invasive Plant News

I highly recommend this document: A Management Guide for Invasive Plants in Southern Forests – even if you are in the north!  This 120 page guide starts with the development of strategies and plans, explains control techniques, and then covers specific invasive plant species.  The sections on development of strategies and plans and on control techniques apply wherever you are located.  Many of the specific plants such as honeysuckle, tree-of-heaven, Russian olive, oriental bittersweet, and buckthorn are in many northern areas too.  And, the guide is free!

The authors are James H. Miller, Steven T. Manning, and Stephen F. Enloe.  The guide is published by the United States Forest Service’s Southern Research Station.

Tree Girdler Saw

Here is what the tree looks like after the cut.

Cuts with Tree Girdler

After making the cut, you can chisel out the portion of cork between the two cuts.  The cork comes out very easily.

Groove Created with Tree Girdler

Then spray the herbicide into the cut.  In this case I sprayed Green Shoots’ foamed herbicide because otherwise the herbicide drips down the side of the tree.

Herbicide Foam in Groove

I spent Sunday afternoon at our family’s property near the St. Croix River.  It was a nice winter day – about 25 degrees.

Tree Girdled with Cuts and Chemical

Our property has a dense stand of pine trees about 40 years old.  My grandfather planted the trees in the 1960s.  We have been thinning the trees for the last 8 years or so after many years of neglect.  This is a lot of work.  This year I decided to take a new approach.  Instead of cutting trees down, I decided to girdle some of them and leave them standing.   After they die, these snags will become great habitat for bugs and, we hope, for woodpeckers and other birds.  Here’s a webpage from the United States Forestry Service on snags.  According to the authors, a snag should be at least 10 inches in diameter at breast height to serve effectively as a snag.  For nesting purposes, it should be 15 inches in diameter at breast height.  (I would say most of the trees I girdled were between 9 and 16 inches.)

At left is one of the trees that I girdled.  I used a Fiskars Brush Axe to make the cuts.  I cut all the way around the tree.  Then I applied a concentrated glyphosate mixture – over 30% active ingredient.  I decided to use the chemical for two reasons.  First, I wanted to make sure I killed the tree.  I have girdled trees in the past that have survived the girdle.  It is not so easy to make sure you have severed all the connections of phloem.   Using herbicide ensures that there is a complete girdle by killing the tissue in the girdled area.  Second, I wanted to kill the tree quickly.  (Straight girdling can take a year or more.)  By doing it quickly, I hope that, come the dry summer season, the trees will long dead and not attractive to bark beetles.

Altogether, I was able to girdle about 35 trees on a 13 acre site in a couple hours. There is no way that I could have cut down that many trees with a chainsaw in the same amount of time. I hope to do at least 30 to 50 trees every year until we have a good number of snags.  I will keep you posted on the progress.