Planted too deeply & volcano mulch

SouthSoundTree

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We know that trees should be planted with the root crown at soil level, and mulch shouldn't be on the trunk. My question is why? One issue is stem girdling roots. What else happens when trees are too deep and the trunk is too moist, physiologically/ biologically-speaking?
 
Theres a gas exchange that gets hindered, The constant moisture makes any wound more susceptible to infection. Thats all I got at the moment. Good discussion I hope
 
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Seems like it doesn't even need a wound. I'll be interested to see what happens with an apple and a peach tree I transplanted to my house that had been 4-8" too deep and never did very well according to the former owner.

"They" say that adding soil is worse of a grade change than removing. In part it depends on how the soil was added. A bulldozer will compact much more than a wheelbarrow.

I've heard of "collar rot" but don't know if its true. If so, what are the causal organisms?
 
I'd say "they" are wrong. How could compacting/ filling soil be worse than cutting off all the roots and removing the organic/microbe layer?
 
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I don't know where "they" said it, I read it. Perhaps "they" were talking about cutting smaller roots that would grow back. I'm open to hearing more from people, for sure. Possibly not an apples to apples comparison??? Cutting grade down could also be done with a bulldozer, with same compaction. Would vary with species, as I assume different ones have different below ground growth habits, as above ground. Some species are very prone to surface roots, others seem to barely have an noticeable roots, even with much bigger trees. Soils will play into this as well, as you noted. Some areas will have deep organic layers, whereas others shallow. Perhaps too general of a statement to have been made. Would be interesting to hear from people with a lot of site development experience with mature trees.
 
My understanding is that it has to do with oxygenation: an established tree (even a young one) is not able to physically move itself to its' roots optimum planting depth. Too deep is worse than too shallow (marginally) and the volcano mulch thing is an abomination. Major disease vectors because of continual moisture and constant danger from fungi. Some trees are sensitive to a grade change of 2" where others will tolerate much more. Sadly, grade change is rarely recognized as primary contributor to a tree's death because it takes a number of years for the tree to succumb.
 
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Constant moisture against bark that is genetically designed to be above ground and in contact with air can cause degradation and decomposition of the bark which if ledt long enough will girdle the trunk and leave no open pathway for minerals and water to rise as well as produced starches and carbs to descend to storage in the roots. If the tree is grafted, burying the graft usually brings the onset of massive suckering at the base as well as the potential failure of the graft due to decomposition of tissues.
In layman's terms, it just ain't right.
:)
 
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Amy told me that at her Master Gardeners class, the guest speaker from a nursery that specializes in edibles told them that grafted fruit trees could be buried up to the graft. I thought "bogus", but I don't know much about grafted trees, but I still thought "bogus". Master Gardeners sometimes think that they know it all, because they have had "expert" instruction.
 
The main thing on adding soil is that it reduces oxygen to the root, the gaseous exchange that was mentioned. In low oxygen situations, respiration is reduced. Respiration is required for the plant to take in water and the accompanying nutrients. This is the phenomenon that leads to what we call wet wilt. The ground is water logged, but the plants are wilting. And in most cases, the first reaction is to water the wilting plant more.

Without oxygen, respiration or plant growth is not possible. A soil without oxygen is referred to as anaerobic. Bacteria are some of the few things that exist well without oxygen and they tend to operated by creating chemicals that are toxic to or macerate (dissolve) cell walls and other materials. This is why the root systems that we pull out after a tree has died due to planting too deep or over watering is usually just a big gob of mush.

In a lot of cases the amount of soil added is not as critical as the type. A half inch of heavy clay will shut off air much more than 3 inches of coarse sand or gravel. The extra mulch will indeed hold in extra moisture and allow roots to grow up into it, if the tree is planted at the proper level. Then you can get the girdling roots forming that would if the tree was planted too deep.

Also, the tree species makes a big difference. Trees used to temporary flooding, bottomland trees such as elm, boxelder, willow, etc, will handle some compaction better than upland trees like oak and hickory that grow on well drained soils. Species that are highly dependent on fungal mycorrhizae are also affected more since fungus needs oxygen to live. We see this in the big white oaks of the midwest and MB may have noticed it in the case of Little Leaf disease in the southern pines in the bayou country. Those pines that are growing on slight knolls are not as affected as those growing on the flats. The fungal roots, not killed by lack of oxygen during high water, keep the tree slightly healthier and therefore more disease resistant.

Does this help or confuse you more??
 
Great post Bob. Since deep planting is associated with stem girdling roots, grafting crossed my mind. Roots that try to girdle each other typically end up grafting, what do you think the reason is that they cannot graft to the stem? Or perhaps they do in some of the trees more prone to natural grafting such as willow. I don't believe I have ever seen a willow with a girdling issue
 
The girdling root issue with deep planting has to do, as I understand it, with the roots being able to grow up over the top of the major spreading roots if there is soil or mulch available for them to grow into. If the major roots, at least those in that region of rapid taper close to the trunk, are near the surface, those roots that try to grow over the top and eventually girdle the main roots or stem are air pruned. If you have a volcano of mulch around them this supplies the well aerated, moist environment that the roots will love to grow in.
Another issue is planter beds around the base of a tree. This will keep the collar unnaturally wet and lead to the same problems.
In the a cooler climates, such as ND, the mulch volcano creates a great cafeteria for mice and such during the winter. They can eat in with out having to go out in the cold. Even the mice up here are smart!!!

Here are some videos about root crown excavation. The number 10 one deals with the above issues. I have not looked at all of them, but what I saw I think is a good basis for discussion. http://wn.com/Root_excavation

As to the issue of whether or not to bury a graft, I tend to say to follow the rule of having the root collar at the surface. Again as was said before, the bark above the collar is designed to be in a dry environment, that below the root collar is adapted to a moist environment. Fungi, bacteria, nematodes, and other critters are going to be better able to access the xylem and phloem that is near the surface, if the environment around it is conducive to their thriving
 
In answer to your question about root and stem grafts, here is a quote from an article from The Ohio State University. "Certain trees are more prone to this problem than others. Lindens, magnolias, pines, and maples other than the silver maple are susceptible to root girdling. On the other hand, oaks, silver maple, ash, and elm are well known for their ability to form functional root grafts and are rarely adversely affected by girdling roots." (http://ohioline.osu.edu/hyg-fact/1000/1139.html) I think the reason that stem girdling roots do not graft to the stem is due to the physiological differences that make one tolerant to a moist environment and the other to dry.
 
Bob is dead on about the oxygen deficiency with too much mulch/topsoil. A lot of girdled root problems are due to container born plants and the limited space the allow.
 
Thanks for the links Bob
the best vids on root pruning are #11 and #13. John's a pro who gets to the root cause of tree problems, and prunes them out. The OSU "fact" sheet is 17 years old, and i know the author would not say all that today. the attached book chapter from 2007 was heavily peer-reviewed.
 

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So, what is the story with not back filling over pruned roots? Just for ease of inspection? Minimize infection?
 
So, what is the story with not back filling over pruned roots? Just for ease of inspection? Minimize infection?

yes and YES and also to prevent new sgr's. Bob, of course I'm biased toward the new info (Buy the Book!), but anytime I see a U "fact sheet", just like every time I hear anecdotal experience, I look for independent corroboration. Universities like groups of practitioners can be echo chambers. Inbred information oft goes awry.
 
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