Earlier in this blog we had a rather robust discussion about the merits of transplanting trees bare-root. Bare-root transplanting has had a renaissance in arboricultural circles, based in large part on the work of Dr. Nina Bassuk and her colleagues at the Urban Horticulture Institute at Cornell.
As our bloggers noted, transplanting trees bare-root has advantages over balled and burlap trees (larger portion of the root system stays with the tree) and over container-grown trees (more natural root system development). One disadvantage of bare-root trees is the need to protect roots from desiccation during storage and handling. Also, some trees respond better to bare-root treatment than others. Nevertheless, I think we will continue to see increased interest in bare-root planting. One notable trend is planting relatively large-caliper (4” and larger) trees bare-root. This phenomenon has coincided with the development of the air spade, a tool which produces powerful a jet of air that allows arborists or nursery workers to carefully excavate an entire root system with minimal disturbance. Unlike digging a tree with a traditional tree spade, the air spade allows nursery workers to maintain virtually the entire root system when lifting a tree. Last week, my esteemed colleague, Dr. Tom Fernandez, and his Nursery Management class at MSU worked with Paul Swartz, MSU campus arborist, to lift a 10” caliper weeping white pine from our campus nursery. Members of the class took turns using the air spade to excavate the entire root system of the pine. Since the class is divided into lab sections that meet throughout the week the process was spread over several days. After each lab period exposed roots were covered with wet burlap to prevent drying. By the end of the week the tree was ready for lifting and was transported via flatbed truck to its new home at the front entrance to the MSU Horticulture Teaching and Research Center. Paul Swartz reports that he has successfully used the air spade to move several large specimens on campus and the technique is especially useful for moving trees from tight spots that can’t be reached with a mechanical spade. As more and more arborists acquire air spades look for this technique to become more common.
NOTE: Photos courtesey of Dr. Tom Fernandez.
The air spade uses a stream of compressed air to excavate roots.
Note the extent of the root system. A 90″ mechanical spade would have missed at least half the roots of the tree.
Once the roots are excavated the tree is ready for lifting.
The pine resting comfortably at its new home.
13 thoughts on “Baring it all, again.”
This is so cool, Bert! What I like the best from a visual perspective is that you can see what tree root systems really look like. As I keep telling people, tree roots don't look like carrots! Thanks for posting this. (I now have a new tool on my birthday wish list…)
This is a great idea – I haven't even heard of such a tool before.
Would I be right in thinking that usuing this air spade would generally take longer to excavate a small to medium tree than other traditional methods?
Yes, there's no question standard mechanical spades will be faster. The length of time it takes to dig a tree with an air spade will vary widely depending on soil conditions. Some commercial arborists are already using this technique. The main applications are trees where you can't or don't want to use tree spade (next to buildings or near overhead or underground utilities) and high-value specemin trees where you want to make sure you take the effort to get as much of the root system as possible.
The air spade is a great tool, but more emphases should be placed on the exact uses of the air spade in future discussions. The air spade can in no way replace traditional methods of tree harvesting such as pot-in-pot and balled-n-burlap, due to the time it takes to excavate the tree. However, the air is a great tool to relieve compacted soils around distressed established trees that have had the soil around the base of the tree compacted by constant foot traffic (like college campuses) or site construction. The air spade can prove to be a marketable tool for specialty tree removal and tree recovery.
We have used an air spade for root collar inspections on several occasions over the past 5 years. We have two contractors in town who own one.
I hadn't thought about using it for transplanting. Does anyone have any thoughts on why you wouldn't be able to transplant this way in Southern California?
Tim, it should work fine as long as it's cool and moist enough so that the root system doesn't get too water-stressed. If you do try it, let us know how it goes!
I would practice on a few 'disposable' trees before you get going. As you know, the air jet from the spade is powerful – you can do some damage with a moment's inattention. Also a few practive trees will enable you to better judge how long a job may take.
Air tools are great for moving trees, and for moving shrubs as well, in tight situations where you want to preserve the roots of surrounding plants to remain.
Mike Furgal, a Cornell grad and Massachusetts arborist started experimenting on using an air spade to transplant specimen trees in 2004, and he has developed the technique so that it's useful in a huge range of situations. He's now taught 2 workshops here to the Mass. Arborists Association, so word is getting out. I've been recording how the process works on two blogs: http://www.takingplaceinthetrees.net and http://www.takingplace.net; to see lots of captioned photos and explanations visit the blogs.
Once an arborist knows how to do the moving, it takes less time than it takes to dig and B&B a specimen tree. A tree spade takes less time still — but as Bert points out, you lose a lot of roots.
One other advantage of bare-rooting woody plants is that you avoid the moisture-movement barrier that a root ball-native soil interface often creates; planting trees bare root lets the roots adjust right off to the native soil, and moisture is available immediately to all the roots.
Deb, you're a woman after my own heart! Thanks for joining the discussion!
As a garden writer, I'm wondering about the possibilities for such air tools for the backyard gardener. If you know of any such tool, please contact me.
This is probably beyond what most homeowners would want to tackle in terms of expense and effort. Air spades retail for about $1,200 and the operator will also need to rent an air compressor. The operation is relatively straightforward but it is a loud, messy job. In the future I think we will see more tree service companies and landscapers offering this type of tree moving as a service.
This is really cool! Haven’t seen Air Tools being used like this in Australia. May have to look into it further!
There are some arborists that are doing this with large trees – e.g., moving trees instead of removal before construction. In this case, the tree didn’t make it, so certainly not fool-proof. Based on our recent research on bare-rooting, I suspect transplanting in spring while still dormant would have a better chance of success.