# Two tier root system on T. baccata??



## Cornubia06 (Dec 20, 2008)

Hi

Anyone privvy to this two tier root system theory in Taxus as we have a large consignment of plants with too high soil levels (I wasnt present when tagging) with adventitious roots present which in my opinion have been ignorantly maintained in the nursery however, the consultant we are using tells me that this is unique to Taxas and that they would naturally put out intercepter roots above the root flare when leaf litter etc builds up in a woodland environment to such a level where the existing feeder roots become buried resulting in severely reduced gaseous exchange etc etc. 
From what I understand from the consultant is that these intercepter roots are not inclined to girdle as they develop and there will be no die back/rot of the now redundant and buried existing feeder roots and no cambial rot on the now buried trunk portion above the root flare.

My immediate thoughts are:

1. Are these 'intercepter' roots not just naturaly occuring adventitious roots as the tree adapts to its changing environment just like any other tree/shrub would do and not unique to Taxus?

2. Surely these intercepter roots can potentially girdle as any other adventitious root can. Do roots not naturally develop in the direction which offers them the best environment whether it be up, down, left, right or in a girdling fashion?

3. Granted, non-subterranean Taxus wood is more resistant to decay than others but it will still rot under the right circumstances over time and compromise the longevity of the plant. So, will soil levels/organic matter etc rising above the root flare in the right circumstances not induce cambial rot at some point and compromise longevity?

I appreciate all sorts of physiological changes take place and vascular bundles retreat further into tissue during secondary thickening etc in the roots but will this happen above the root flare and reduce the risk of cambial rot? Are adventious roots not born from latent buds in the trunk and will consequently be poorly attached and prone to parting from the trunk, in the event of high winds for example (can't stake as we are talking mass hedge planting of several hundred plants and hence the concern and clarification needed). 

I can't find any blurb to confirm the two tier theory being recognised and unique to Taxus so I thought I would call upon the wisdom of you lot. 

What d'ya reckon?


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## S Mc (Dec 21, 2008)

I have tried to google something to support the "two-tiered root system" and am not coming up with anything.

I tend to agree with your thoughts in that if a tree/shrub has medium built up on the trunk which provides a suitable environment, adventitious roots are going to develop. Some species are much more adept at doing this than others. Evidently this is the case with Taxus.

Taxus are susceptible to _Phytophthora_ root rot so that would support your concerns about cambial/root rot if, again, conditions were suitable.

Taxus are an extremely long-lived species, and have adapted to survival as their forest floor has changed; hence the findings that they can survive a secondary root system (as time has built up the forest floor). However, I can't imagine a new seedling in a forest setting will bury itself deep creating an immediate secondary root system. I would think that starting the plant off with adventitious roots due to nursery practices which have built up the soil artificially would not be in the plants' best interest.

I will be interested to hear more on this.

Sylvia


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## Cornubia06 (Dec 22, 2008)

BELOW!  

Come on you lot or I'll chuck a cone at yews (pun intended).

Where are the likes of dunlop, treeseer, treeco, rbtree, jp sanbourne, elmo etc I always appreciate their posts and sorry if i got your names wrong or missed out a good poster.

Thanks for the reply S Mc.


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## treeseer (Dec 23, 2008)

"1. Are these 'intercepter' roots not just naturaly occuring adventitious roots as the tree adapts to its changing environment just like any other tree/shrub would do and not unique to Taxus?

yes natural in many the taxus may have a special pattern 

2. Surely these intercepter roots can potentially girdle as any other adventitious root can. Do roots not naturally develop in the direction which offers them the best environment whether it be up, down, left, right or in a girdling fashion?

well there is that but first there is a certain momentum in radial growth from buds released in the cambium; they would tend to grow away from stem. It's when they grow upward that the worst issues arise.

3. Granted, non-subterranean Taxus wood is more resistant to decay than others but it will still rot under the right circumstances over time and compromise the longevity of the plant. So, will soil levels/organic matter etc rising above the root flare in the right circumstances not induce cambial rot at some point and compromise longevity?

yes if wet will rot so keep dry as possible

I appreciate all sorts of physiological changes take place and vascular bundles retreat further into tissue during secondary thickening etc in the roots but will this happen above the root flare and reduce the risk of cambial rot? 

maybe; depends on vitality, etc.

"Are adventious roots not born from latent buds in the trunk 

not necessarily; could be adventitiously-formed, EPIcormic buds and not latent/preexisting

"and will consequently be poorly attached and prone to parting from the trunk, 

yes, epicormic growth from newly formed buds is more poorly attached than ENDOcormic growth from preexisting buds, but still should stay attached if other roots are intact so stability should not be a problem.
roots are like buy wires.

"I can't find any blurb to confirm the two tier theory being recognised and unique to Taxus 

your consultant no doubt observed this in taxus. her/his advice very good. yes check for these new roots girdling stem but if not let them grow. after removing as much soil as possible without sacrificing important roots, aerate the remaining soil and improve drainage of site.

re blurb here's an excellent article on this, found surfing the ISA site:

http://www.isa-arbor.com/publications/arbNews/pdfs/Jun05-feature.pdf

pics as always would be immensely useful.


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## Cornubia06 (Dec 24, 2008)

Thanks for the input Treeseer, much appreciated.

That is a great link which puts everything into perspective. So broardly speaking, one could say that Taxus react in pretty much the same way as any other plant except Taxus may be better at it, but, there are still the usual risks present having been forced to react and adapt and obviously undesirable in the first place.

I notice the link advises small adventitious roots upto a certain diameter be pruned out while reastablishing the soil level before planting and you advise to leave them be if they don't look likely to girdle. Just to clarify, even if the new advetitious roots look fine before planting, is there not still the possibility they might girdle following planting and should be removed? (management of stem girdling roots by Johnson and Hauer 2000 is on the to buy list.

I suppose its the different terminology used (interceptor=adventitious and two-tier=primary/secondary) and suggesting its unique to Taxus thats got me curious. Re. the two-tier or primary and secondary root systems, if and when the original primary system becomes defunct will it not begin to decay despite being made up of root tissue causing further undesirables? 

Thanks


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## treeseer (Dec 24, 2008)

"One could say that Taxus react in pretty much the same way as any other plant 

no, some plants do not seem able to adapt by growing new roots off the stem

"except Taxus may be better at it, but, there are still the usual risks present having been forced to react and adapt and obviously undesirable in the first place.

yes

I notice the link advises small adventitious roots upto a certain diameter be pruned out 

yes smiley here says .6 cm but elsewhere said 1.2 cm; obviously it depends on size of stem, vitality of new root growth etc etc

while reastablishing the soil level before planting and you advise to leave them be if they don't look likely to girdle. Just to clarify, even if the new advetitious roots look fine before planting, is there not still the possibility they might girdle following planting and should be removed? 

no if they are oriented outward then they would not girdle would they? 

(management of stem girdling roots by Johnson and Hauer 2000 is on the to buy list.

this is not being sold that i know of--contact U of Minnesota if you want, but shipping it to france would be a waste of $. It has Nothing to do with mgt but one paragraph at the end speaking in very general terms. this is the only problem i have with costello's fine article is that he overstates the content in references cited.

I suppose its the different terminology used (interceptor=adventitious and two-tier=primary/secondary) and suggesting its unique to Taxus thats got me curious. 

yes this seems overstated and somewhat of a rationalization--as Sylvia pointed out, the situation is not ideal and should have been avoided by keeping the trunk flare visible in the nursery.

Re. the two-tier or primary and secondary root systems, if and when the original primary system becomes defunct will it not begin to decay despite being made up of root tissue causing further undesirables? 

good point. if you are in europe i suggest you consult european nursery standards which are different from US. please let me know what you find as i am resarching root mgt for a writeup (that is overdue)


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## Cornubia06 (Dec 28, 2008)

treeseer said:


> no if they are oriented outward then they would not girdle would they?
> 
> I would imagine individual specimens in a natural environment with little competition would be less likely to form girdlers from upward growing adventicious roots than the situation I have; mass planting @ 1m centres in varying length and width beds with drip line irrigation. In this situation there will surely be hundreds of micro-environments resulting in a huge competition and roots growing in all different directions - in time there could be roots of one plant girdling the trunk and/or roots of another etc. Also, the plants were balled in hessian and retained in steel wire. Will the hessian itself not absorb moisture creating a nice little source so newly formed white roots need not venture too far and further add to the risk of self girdling? So many variables - interesting stuff.
> 
> good point. if you are in europe i suggest you consult european nursery standards which are different from US. please let me know what you find as i am resarching root mgt for a writeup (that is overdue)



Launched a bit of a search on this and have found little so far. I'm not sure this is a subject that well recognised and the blurb is still embrionic. Will keep you updated if I make any discoveries and vice versa.


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## Cornubia06 (Dec 28, 2008)

Ha ha, how does one multi quote effectively?? I click the button and nowt happens!


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## treeseer (Dec 29, 2008)

Cornubia06 said:


> I'm not sure this is a subject that well recognised


well you got that right; i wrote the attached 1.5 yrs ago and just about all the useable info on this i cited.

are you still negotiating with the nursery?

"I would imagine individual specimens in a natural environment with little competition would be less likely to form girdlers from upward growing adventicious roots than the situation I have; mass planting @ 1m centres 

that is pretty tight.

"in varying length and width beds with drip line irrigation. 

drip aggravates trunk rot issues if emitters are too near trunks; common here 

"In this situation there will surely be hundreds of micro-environments resulting in a huge competition and roots growing in all different directions - in time there could be roots of one plant girdling the trunk and/or roots of another etc. 

yes but 1m away this is a faroff and relatively minor problem.

"Also, the plants were balled in hessian and retained in steel wire. Will the hessian itself not absorb moisture creating a nice little source so newly formed white roots need not venture too far and further add to the risk of self girdling? 

did not remove top of wire and hessian (burlap?)?? tsk tsk, not up to ANSI standard, how about euro standards?

"So many variables - interesting stuff. 

:agree2:


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## Cornubia06 (Dec 29, 2008)

Rest assured, the plants were planted to Ainsi, British Standards & European. Thanks to the ISA, those countries who give a damn are all on the same page when it comes to proper tree care. 

Off to the snow for couple days... to be continued...


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