Tree Tubes on American Chestnut Trees

Tree tubes are finally fulfilling their promise as an establishment aid for American chestnut seedlings.

If ever there was a perfect candidate tree for tree tubes it would seem to be the American chestnut tree.  Billions of majestic chestnut trees were wiped out by the fungal blight that swept through its range in the early- and mid-1900s.  It has been the focus of heroic re-establishment efforts on the part of organizations such as the American Chestnut Foundation and thousands of dedicated scientists and volunteers.  Every chestnut seed or seedling planted is rare & precious, and critical to the long-term success of re-establishment efforts.  But chestnuts are also extremely vulnerable to all of threats to successful regeneration that other species face, including deer browse, competing vegetation and periodic drought stress.

So given the value and importance of each and every chestnut seedling planted and the number of threats they face, one would think that using plastic tree tubes on American chestnuts would be a no-brainer... and indeed American chestnut enthusiasts were some of the first tree planters to recognize the potential benefits of tree tubes and give them a try.  Unfortunately, the performance of those early, unvented tree tubes on American chestnut seedlings left a great deal to be desired.

It turned out that chestnut seedlings grown in tree tubes were particularly vulnerable to winter injury and die back.  They also grew with elongated, spindly stems that often formed a spiraling or helix growth habit as they worked their way up the tree tube.  Word of these issues quickly spread in chestnut growing circles, and chestnut planters either switched to using 2ft or 3ft tree tubes (shorter tree tubes provided rodent protection but did not cause die back or spiraling growth) or stopped using tree tubes altogether.

Growers of Chinese chestnut trees, incidentally, experienced and reported these same problems, and many became disillusioned with tree tubes.

Recently, however, chestnut planters - both of American and Chinese chestnuts - have recognized the major advancements in tree tube design - most notably the addition of ventilation, better light transmission properties and larger tube diameter - and have given them another try.  This time around the results have been outstanding.

In this blog I have often discussed the evolution of tree tubes as the story of two eras:  Before Venting (BV) and After Venting (AV).  The entire history of tree tube use and effectiveness in North America can be divided into these two categories; the un-vented tree tubes that first came over from the UK and worked well in their moderate and very forgiving climate, and the vented tree tubes that work in the extreme climates - both cold and hot - found in the United States.  Nowhere is this dichotomy of BV versus AV illustrated more starkly and dramatically than with American and Chinese chestnut trees.

In coming weeks we will be posting accounts and photographs of tree tubes on American chestnut and Chinese chestnut trees.  Healthy, rapid growth and straight trunks have been the rule, as you see in dramatic fashion here:

(Click to enlarge)

This is a Chinese chestnut tree growing in Mississippi.  It was planted in July, 2012 as a 12 inch seedling.  It was protected with a 4ft tall tree tube, and was watered to help it survive the late season planting.  It didn't put on any additional growth for the remainder of the 2012 season.... in other words in entered the 2013 growing season 1 foot tall.  This photograph was taken in August, 2013.  The tree grew more than 8 feet in one growing season.

More important than the rapid rate of growth:

1) The tree - and many others like it in the same planting - is perfectly straight, with no sign of the spiraling growth seen in the early days of chestnut seedlings in un-vented tree tubes.

2)  The trunk diameter - while thin relative to it (amazing) height, as you'd expect with any tree tube grown seedling - is very robust.  This also due in large part to the adoption of flexible tree tube stakes such as 1/2" schedule 40 PVC, as was used here.

Note: That "tray" at the base of the tree is a revolutionary weed mat developed in Israel called the IrriPan Weed Mat.  It blocks weeds, captures rain water and funnels it to the tree, reflects light up to the tree, and recycles soil moisture.

Follow this blog for more upcoming posts chronicling the use of tree tubes on American and Chinese chestnut trees.

Tree Tube Myths: Does this look like a spindly stem to you?

One of the "knocks" against tree tubes over the years is that, while they unarguably accelerate height growth, they produce trees with thin spindly stems.  To this criticism I have two responses:

1) A six foot tree with a thin stem and a sturdy treeshelter in place to support it until the stem thickens up enough to support itself is a whole lot better than the alternative:  A seedling without a tube that is continually browse by deer to the point where it dies or is stunted at knee height for years.

2) Today's vented tree tubes and flexible PVC stakes have combine to make a myth out of the "spindly stem" critique of tree tubes.  Thin stems are a thing of the distant past.  Take a look:

(Click to enlarge)

This is the trunk of a hybrid oak from Mossy Oak Nativ Nurseries planted in a 4ft Tubex Combitube Plus Tree Tube.  Here's the chronology:

* Planted as 18 inch seedling in March, 2011

* Photo taken on August 2, 2012 - less than two complete growing seasons later!

The tree is now well over 10ft tall.  But most exciting to me is the large caliper of the trunk immediately above the tree tube.  You can see that with today's vented tree tubes and flexible PVC stakes it's not just a matter of producing the same amount of biomass growth and just "stretching" it in height, as might have been the case with early tree tubes.  No, this tree is putting on a HUGE amount of total biomass (especially when you consider that stem diameter is the best "window" into what's going on with root growth below ground).

As with so many discussions of tree tubes it comes down to B.V. (Before Venting) and A.V. (After Venting). Before venting trees were definitely better off with tree tubes than without, but exhibited some "side effects" like thin stems.  After venting tree planters are realizing the full potential of tree tubes and seeing astounding growth, both in terms of height but - more importantly - in terms of stem diameter.

Think of it this way, using a computer analogy:  Unvented, small diameter tubes of the past = MS-DOS.  Today's vented, large diameter tubes combined with flexible PVC stakes = Windows XP.

Extending 4ft Tree Tubes

Expanding on our recent theme of choosing the best tree tube height, here's a great post from Tree Protection Supply on their new Tree Tube Extender product.

4ft tubes provide enough deer browse protection 75% of the time.
5ft tubes provide enough deer browse protection 90% of the time.

A perfectly legitimate strategy is to start with 4ft tree tubes and then, if deer start browsing trees as they emerge from the tubes, use a 2ft tree tube extender to get another 2ft of protection - not to mention another year of very accelerated growth.

Chances are the deer will only browse certain species as they emerge from the tubes, or will only browse in certain places (such as next to the field where they bed down, along a creek, etc.) so you might only need tube extenders for a small percentage of your 4ft tree tubes.

PVC tree tube stakes make this easy, because you can just snap a 2ft extension to the the top of the 4ft stake, and you're good to go.

It's so cool to see so many tree tube companies getting on board with the vented tree tube plus PVC stake combination - and more importantly to see so many landowners reaping the benefits!

Tree Tube Innovations, Part 2: PVC Stakes

I find it interesting that the 2 major innovations in Tree Tube design and performance in the last 20 years have both originated with customers, and not the companies that make and sell tree tubes.

I also find it embarrassing, since I am one of the few guys who has been selling tree tubes from the very beginning.

The first major innovation was ventilated the tubes.  I covered venting in detail in a recent post.  I consider the advent of vented tree tubes to be so important that in my mind I divide tree tube history into two distinct eras:  Before Venting (BV) and After Venting (AV).

The second and more recent innovation is the use of PVC Tree Tube Stakes.  Trust me, as someone who has sold tree tubes for 23 years, the stakes needed to support the tubes have been the biggest headache and source of frustration.

Tree tube suppliers didn't come up with the idea of venting the tubes because they were working under a false assumption: That the reason tree tubes accelerated growth was because they functioned as an almost hermetically sealed growth chamber.  It took customers drilling holes in their tubes and reporting their great results to make us realize that tree tubes accelerated tree growth despite being hermetically sealed environments, and that they accelerated growth even more - and without the negative "side effects" common to unvented grow tubes - when holes were punched in them allowing a freer exchange of carbon dioxide.

Similarly, tree tube makers didn't develop the idea of using PVC tree tube stakes because of another false assumption, namely the assumption that tree tubes and stakes are two separate product lines rather than two components of the same product system.

I guess another false assumption is that when we think of "stake" we naturally think of wood.

A third false assumption (gosh we tree tube peddlers sure have made a lot of them!) was the idea of tree tubes as a "plant and walk away" system for tree establishment (which in terms of feasibility is right up there with cold fusion and perpetual motion machines) - the idea being that the tree tube would photodegrade and the stake would biodegrade over time.

This "hat trick" of false assumptions meant that white oak and other decay resistant hardwood lumber became the workhorse tree tube stakes for two decades.  More recently white oak has largely been replaced by bamboo as a cost-saving alternative.

It's safe to say once again that tree tubes succeeded despite the use of wood, bamboo or any of the other materials used as tree tube stakes.  The basic problem with wood and bamboo stakes - especially bamboo - is that they break, split and degrade too soon.  There's any old joke about ranchers being full time fence repairmen who keep livestock as a hobby.  Well, with wood and bamboo stakes tree tube users were essentially stake replacers with a tree planting hobby.  That's how much time was spent in replacing broken and rotten stakes.  (A customer told me just this morning that he has never made a trip to check on his trees without having to replace old wood or bamboo tree tube stakes.)

But the problem with wood and bamboo stakes goes far beyond breakage and biodegradation.  The deeper problem is that they don't complement the tree tubes.  They don't contribute to the performance of the tree tubes.

One side effect of growing trees in tree tubes - even vented tree tubes - is that the trees tend to have thin stems relative to their heights.  Tree tubes channel growth upward, and the trees are isolated from the environmental feedback - especially the swaying and shaking effects of the wind - that trigger growth responses that allocate more growth resources into thickening and tapering the trunks and developing bigger root systems. 

About 5 years ago I started hearing about customers using 1/2" pvc conduit as tree tube stakes.  I am embarrassed to say that - as I was with grower reports of the benefits of venting the tree tubes - I was skeptical.

The solution was in the hardware store the whole time!

1/2" pvc conduit makes the best tree tube stake, swaying

in the wind but never breaking.

And once again, I was wrong.  Way wrong.

We already know that we have to go back at some point - 3, 5 or 7 years down the road - and remove the tree tubes from the successfully established trees.  Therefore we know that we can retrieve (and then reuse) a non-biodegradable stake at that point... so biodegradability is not a critical factor for a tree tube stake.  

It's also easy to understand - as my customer did this morning - that PVC tree tube stakes won't break, and will save dozens of extra trips to the field to replace broken or rotten stakes.

However, the most important thing about PVC tree tubes stakes is:  They make tree tubes perform even better (rather than being a necessary evil tree tubes - and their users - must put up with and overcome).

They make tree tubes better by providing the environmental feedback - swaying and shaking in the wind - the seedlings in tree tubes don't get with rigid stakes.  Again it is that swaying motion that triggers hormonal responses which in turn "tell" the tree to channel more growth energy into stem thickness and taper as well as root develop (so-called secondary growth responses).

Take a look at the photo above.  This photo was taken late in the second growing season of a hybrid oak grown in a vented tree tube supported by a PVC stake.  This kind of caliper growth was unheard of with rigid wood or bamboo stakes.

This kind of caliper growth means that now when trees emerge from tree tubes they don't - as they had to in the past with rigid stakes - slow their height growth while reallocating growth energy to stem caliper and taper.  Now they get to the top of the tube... and keep right on going!

So once again, to my customers:  You were right, I was wrong.  Tree tubes & stakes are not two separate products.  They are component parts of the same product, and need to work together symbiotically to achieve the best results. 

PVC tree tube stakes solve all of the problems of wood stakes, completely negate one side effect of tree tube use.  Best of all, they do so for less than the delivered cost of bamboo stakes, and WAY less than the delivered cost of white oak stakes (and, by the way, much MUCH less than fiberglass stakes).