The invasive plant video was sponsored by the British Columbia Invasive Plant Council. It is fantastic. The drawings are captivating! The contest asked schoolchildren from British Columbia to create, draw, and describe their own invasive plant.
Archive for January, 2011
Predicting the Spread of Invasive Species such as Japanese Stiltgrass
A new website at the Indiana University focuses on the predicting the spread of invasive species. Japanese stiltgrass is a major topic. Angie Shelton is the creator. Indiana is on the edge of the area being invaded by Japanese stiltgrass. Japanese stiltgrass seeds are believed to have been in packaging material from China. The seeds were released in Tennessee in 1919 and have spread from there.
Macalester Professor Argues Invasive Species such as Buckthorn Not a Threat
Professor Mark A. Davis argues that invasive species such as buckthorn are not a major environmental threat. He was recently interviewed in an article in Scientific American: A Friend to Aliens: Are Invasive Species Really a Big Threat? Scientific American, January 24, 2011. This article at Macalester’s website, Species Defender, explains his position in some detail.
Invasive Weed Trees – Herbicide Use – Time of Year – Apply in the Winter!
- Buckthorn Stand in Winter
People generally assume the best time to use an herbicide on an invasive tree like buckthorn is when the tree has leaves on it. Obviously, for foliar applications of herbicide, this is necessary. But what is the best time to do cut-stump, frill (hack-and-squirt), or injection treatments? These can be done anytime of year because the herbicide is introduced directly into the cambium of the trunk of the tree.
After many years of trial-and-error, I have found the best time is when the tree has no leaves, i.e., late fall or better yet winter. At least this has been true when using glyphosate-based herbicides on buckthorn in Minnesota. (I use a mixture having between 25% and and 41% glyphosate.)
Be advised – this is to some extent a contrarian position. For example, most labels for glyphosate-based herbicides will say something like this with regard to cut-stump treatments: “For best results, applications should be made during periods of active growth and full leaf expansion.”
However, I do have support for my position beyond personal experience. For example, researchers found that a mixture of Accord and Arsenal (active ingredients glyphosate and imazapyr) worked best when applied to cut-stumps in the fall, i.e., generally not a period of active growth. Ballard BD, Nowak CA, Timing of Cut-Stump Herbicide Applications for Killing Hardwood Trees on Power Line Right-of-Way, Arborioculture & Urban Forestry, 2006;32(3):118-1125.
Why do fall and winter seem to be good times to apply glyphosate based herbicides? For systemic herbicides to work, the herbicide must be transported to the roots. Oregon State University Extension Service, How Herbicides Work, Uptake, Translocation, and Mode of Action, EM8785 (August, 2001). In fall and winter, the tree is translocating sugars to the roots.
What about water soluble herbicides freezing in the dispenser? I have applied concentrated glyphosate-based herbicides at low temperatutres – right around zero degrees F. I have never had a problem with the dispenser freezing. Perhaps the salts in the concentrated glyphosate-based herbicide prevent this.
In any event, give a winter herbicide application a try. In another post I will talk about other advantages of winter herbicide applications.
Invasive Plants Cause Smog? – Kudzu Reacts with Nitrogen to Produce Ozone
Ugh! Not only does it crowd out desirable plant species, Kudzu emits chemicals that react with nitrogen in the air and form Ozone. This is a problem today. According to researchers at the University of Virginia, Charlottesville, Kudzu directly causes a thirty percent increase in Code Red Air Quality Alert Days. Here is a more complete article on kudzu’s effect on air quality from the American Geophysics Union.
Eradicating Invasive Trees and Shrubs – Video on New Foam Herbicide Dispenser from Green Shoots
Here’s a video previewing a forthcoming new product from Green Shoots: Invasive Weed Trees – Killing Them with a New Foam Herbicide Dispenser from Green Shoots. The device dispenses an herbicide foam that sticks well to plant surfaces. The dispenser works especially well with cut surface, cut stump, frill, hack-and-squirt applications commonly used for eradicating non-native and other problem trees. The device also works well for exotic or invasive shrub species. The product should be available in April.
I am part-owner of Green Shoots. Invasive Plant News will publish news about new products from any reputable company. If you hear of new products for invasive plant species, please contact us!
Controlling Invasive Woody Plants and Trees Using the Tall Stump Treatment Method – Part I of II
Fig. 1 Cutting Tall Stump
Eradicating a large number of weed trees such as buckthorn can be daunting, especially in a thicket. It’s difficult to manage all your equipment – loppers, saw, spray applicator. Branches poke at you and hook your clothing. It’s easy to misplace tools. If you are using the cut stump method, the cut tops of the trees also get in the way. It’s easy to miss some of the stumps and not apply herbicide. This usually means the sprouts will quickly come out of the base of the stump.
I call the technique described here the “tall stump treatment method.” I have mostly used it on buckthorn in a northern climate (Minnesota). However, I believe the technique should work on many other invasive trees.
Timing – Best to Treat in Late Summer, Fall, or even Winter
I find it best to treat trees with chemical in late fall or, better yet, winter. It is easier to see and maneuver without all the foliage. More importantly, it is more effective. Fall and winter are when nutrients are being stored in the roots. That’s where you want the herbicide to go too.
Stage 1 – Cutting the Tops of the Weed Tree
This first stage can be done at any time of year because the stage doesn’t involve using herbicide. All you need is a pair of loppers or a saw (depending on the size of the trees). I dive into the thicket (wear safety glasses because branches can poke your eyes) and cut each tree about waist height as shown in Fig. 1. If there are other branches below the main cut, I cut those off too. This leaves a barren trunk about 2 to 3 feet high. I repeat this cutting technique with all the trees in the area that I plan to treat in this batch. Next, I haul out all of the cut tops of the trees to a burn pile, chipping area, or other storage area.
You can leave the tall stumps for several months before applying herbicide. The longer you wait, the more re-growth you will have. However, most of the growth will occur just below the cut (as opposed to at the base of the tree), so it shouldn’t be too problematic.
Stage 2 – Frilling and Treating the tall stumps
Fig. 2 Cutting Frill in Tall Stump
For this stage I bring an herbicide spray applicator and a tool for notching the bark of the tree. The notching tool can be a machete or an ax. I use a specially modified tool shown in Fig. 2. However, you can use a hachet, machete, or even a chisel to make cuts (“frills”).
I make the frills as close to the base as possible. Fig. 3 shows the frills cut at the base.
As quickly as possilbe apply the herbicide to the notches or frills – ideally within a minute or two. Otherwise, the tree’s defense mechanisms will seal off the wound and prevent absorption of the herbicide. (If you have waited too long, just re-cut the notches.)
Note: Many of the demonstrations of the “frill method” (aka “hack and squirt”) show the line of frill cuts fairly high on the trunk. I find that these high frills may not completely kill the roots and resprouting may occur.
When making cuts at the base, however, be careful not to get dirt into the notches or on your tools. Soil and dust neutralize glyphosate. If possible, leave the strips of bark from the notch attached to the tree as shown in Fig. 3. Apply the herbicide to all the exposed inner bark – usually it’s lighter in color. In Fig. 3, it’s the reddish tan bark. This inner bark contains the phloem which will translocate the herbicide to the roots. With this application of herbicide, the tree should die within a couple weeks even in the winter.
Avantages of the Tall Stump Treatment Technique
Fig. 3 Applying Herbicide to Frill
In Part II of this series, I will talk about the advantages of the Tall Stump Method.
Other Resources
Here are some other resources that I have found helpful:
- Mandy Tu, Callie Hurd, & John M. Randall, The Nature Conservancy’s Weed Control Methods Handbook: Tools and Techniques for Use in Natural Areas, April, 2001 (This Guide has all sorts of information on various eradication techniques including hack and squirt in Chapter 5. It also has really good information on herbicides and herbicide usage. It is not being updated unfortunately, but virtually all the advice is still good.)
- Pleasant Valley Conservancy, Brush and Tree Removal (This webpage describes the entire process used to convert an area of woody vegetation into a native oak savanna.
- Ken Moore, Eradicating Eucalyptus, Acacia, and Other Invasive Trees, March 2008. (This guidance is especially good for killing large invasive species. Good photographs.)
Invasive Tree Control or Eradication – Guidance from the Wildlands Restoration Team
If you are tackling a patch of woody invasive species for the first time or if you want to get some new ideas, check out some of the guidance documents posted on the Wildlands Restoration Team website. For example “Eradicating Eucalyptus, Acacia, and Other Invasive Species” provides really clear instructions with illustrations. It describes the advantages and disadvantages of the various techniques such as the cut-stump, frill (aka “hack-and-squirt”), and injection methods. The document “Tools for Weedworkers” suggests where you can buy the tools you might need.
Tall Stump Treatment Method for Controlling Invasive Tree Species
This is a talk I gave at the Minnesota Wisconsin Invasive Species Conference 2010.
Invasive Plant News – a blog about plants that are exotic, non-native and generally unwelcome!
Invasive Plant News is a blog about invasive plants. I will also post articles about control techniques, success stories, and people who work in fields associated with invasive plants. If you have any suggestions for articles or want to contribute to Invasive Plant News, please email me: john(at)wowcoweb(dot)com.
