Robinia problem

[Lee Winger]

Really? That's interesting. Any more details?

 

Sorry I should rephrase that, from what I can glean from the net, it seems that only grafted Robinia seem to be afftected, unless of course anyone knows diffferent..

[Amelanchier]

I think we can make some educated guesses. Armchair dendrology / pathology if you like.

 

We know that only the Frisia variety seems to be affected. So it seems reasonable to infer that this disorder affects Frisia because its Frisia. (Seems simple huh, but normally correlation does not mean causation.)

 

So what's different about Frisia?? As Lee's link reminds us; its a grafted variety and its got yellow foliage. It was created by cramming a bit of a naturally occuring yellow sport into the rootstock of a normal R. psuedoacacia.

 

Yellow leaves are yellow because carotenoids are reflecting more visible light than the cholorophyll which is present at lower levels than green leaves - they photosynthesise at a slower rate. Traditionally "yellow" plants / trees are considered less vigourous than their wildtype counterparts.

 

It seems reasonable to infer that less vigour means a reduced ability to compartmentalise as well as slower growth.

 

A vascular wilt fungus clogs and blocks xylem vessels as it is transported (typically from the soil) around the tree. Robinia spp. are ring porous so to begin with, any damage caused by such an agent affects a greater percentage of active vessels.

 

We can there surmise that perhaps the normal Robinia pseudoacacia might have sufficient vigour to compartmentalise any damage and even grow additional vascular tissue over a longer/earlier growing season.

 

Its interesting that the RHS info suggests that it would be a surprise that such an agent could pass through the "graft barrier". What barrier? The tissue is fused?

 

Additionally, lets not think of this disease attacking and affecting different trees. Frisia is probably a graft clone. As a clone, if one tree can be affected...

[David Humphries]

I know of nowt further, than has already been discussed.

 

A local one in decline with classic peripheral dieback.

To be fair, this one's not exactly in the most agreeable of growing site/conditions.

 

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[David Humphries]

Posted on this 'Tree' last October, but this thread got me thinking about a return to compare the general vigour of the frisia as opposed to the psuedoacacia.

 

http://arbtalk.co.uk/forum/tree-health-care/3943-varieties-forms-cultivars.html

 

The frisia is suffering from a modicum of dieback, unlike the psuedo.

 

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[Ruskins Trees]

Saw a discussion on uktc about this, the same week a client phoned up and said the Frisia we planted was stressing, told him about the uktc conclusion, that something was happening to them in the south east, but no-one knew what it was.

 

The client tried to blame us for supplying a unhealthy tree, we went back and forth, eventually he admitted his sisters mature Frisia had also gone down hill.

 

Then at the Chelsea Flower Show this year an AAIS adviser visited our stand to catch up with us, we asked her how here day had gone and the first thing she said is "bl**dy Frisias dying everywhere".

[Steve Bullman]

is your avatar real?

[Paul Barton]

Found this on my computer - forgot I had downloaded it...

Frisia health probs.pdf

[Simon Rotheram]

is your avatar real?

 

aint that the Ruskins truck - they did a move for us at HMP littlehurst?

[j r hartly]

its not down to karma, for every time you get spiked trying to deadwood them is it?

[Ruskins Trees]

There has been a thread about this on UKTC, apparently it is all over the south east and no-one knows what is causing it. An Alice Holt person I spoke to at the Chelsea Flower Show had been on their help desk all day and when I asked her how it had been her reply was Robinias, everyone has dying Robinias. We have stopped supplying them.