arb culture

Hi David, No, it's not sooty bark disease (as far as I can tell). There don't appear to be any symptoms other than the sudden die-back of small to large branches throughout the crown. Usually the affected trees produce reiterative growth in the inner crown and seem to recover vigour (a bit like stag's horns on oak) but often the trees die or get removed because of the massive amount of deadwood they contain. Sometimes they just develop a thin crown and have low vigour for several years - until they recover or die. There are no dead bark patches, there's no sooty growth. Sometimes there's fungal activity at the base, but this seems to be a secondary thing - only coming in (or becoming a major problem) after the tree is already weakened or has died. I know that several long experienced arbs in this part of the world have commented on changes to the way sycamore behaves when cut. I am told that it is considerably more brittle than it used to be - eg it will tend to snap rather than hold and swing on its hinge. I don't know if this has anything whatsoever to do with the condition I've noticed. Cheers

Thanks for the link anyway Jomoco - it was interesting even if it wasn't what I was looking for

Brilliant advice

Hello all, Whilst I'm thinking about tree diseases, I was wondering if anyone ever found out what was causing the geographically widespread die-back (and sometimes death) of sycamores? This is a condition that I started noticing around ten years ago and it doesn't seem to have gone away. Cheers

I was taught that too, but Charles Mynors seems to have other ideas, and I don't think many of us are qualified to contradict him

Thanks guys, I wish we knew more about this disease. I am familiar with the FC advice, but thanks for the link Paul, others may find it useful. The advice it contains is sensible but it is very much the precautionary approach of scientists who don't really know what's going on I agree with Jules that the inoculum for the disease is likely to be fairly ubiquitous over much of England (I don't know about other areas), but I wonder if a healthy tree with a small initial infection will have the same outcome as a healthy tree getting swamped with bacteria from a neighbouring tree. And would a recently dead tree act as a potential 'swamping' event? Do the bacteria continue to survive in the dead tree for long or do fungi and other microbes consume them? In my example the remaining trees are so valuable that I won't be taking any chances - it'll be belt and braces; sterilised tools, minimal cuts, big bonfires, and crossed fingers. But I do wonder - is there any research to suggest that transmission is possible from tools? I doubt most tree surgeons or arborists would go to such lengths after working on horse chestnuts. If chipping is a bad thing to do, it'd be nice to know as well. As Paul points out, most HC arisings are chipped (and probably spread around elsewhere) these days. And I'd be surprised if most dead HC's don't end up as firewood in suburbia. It seems odd to me that a disease of such importance to amenity trees is so little understood after it's been around for so long. It's been around for about ten years now and the leading authority on these matters (the FC) still don't seem to know how it is spread or how it progresses after infection, and they are therefore unable to provide anything other than generalist precautionary advice. Disappointing. If anyone does know more about this disease it would be brilliant to know

Hi Paul, Thanks for that. I've noticed something similar with regards to variation of susceptibility. I've also noticed that the trees which show a tolerance to infection seem to have good years and bad years. I've surveyed affected trees which looked very poorly at the time and recommended them for removal, six years later some of these have not been felled and appear to be in excellent condition - sometimes it's nice to be wrong :-) I'm guessing though that having a large mature tree which has recently died from this disease is not a good thing for nearby unaffected trees. Especially if any of them have low tolerance (which we can't tell until it's too late). So I'm trying to work out what to do with the dead tree - should it be felled? If so, should we burn the arisings? I'm guessing that ringing up and chipping would be a really good way of spreading infectious material - but no-one seems certain :-(

Hello, I'd strongly advise that you sort out ownership of the tree before going any further. Obviously I also recommend that you obtain advice from a suitable professional, but they will be limited in what advice they can give until the ownership of the tree is confirmed. As for your query as to whether a building can be constructed within the RPA? The answer to this depends on many factors, but it might be possible.

Hi everyone, I've been volunteering at a site in York which has some really lovely large mature horse chestnuts. They're open grown with minimal grazing, so they have the wonderful sweeping boughs coming down to ground level. Unfortunately one of them has recently succumbed to the canker and suddenly died. This is sad, but even more of a concern is the idea that the disease might spread to the other very valuable trees. I'm familiar with the FC advice page on this disease ( Forest Research - Bleeding Canker of Horse Chestnut ), but it seems a few years old now and I was wondered if there had been any updates on how to deal with this disease? Cheers

Another thought - if you sub it out to someone nice, then they might even help you with some of your questions on how to do surveys - then you'd be one step closer to being able to do surveys yourself.

Oops, misread that the first time - sorry. I think the probability of 1 person out of 1024 correctly predicting a sequence of ten coin tosses would be closer to P=0.63 :-) However, post event, I would agree that the probability of the winner correctly predicting the sequence of ten coin tosses would be 1. That would be because; in order to win they would have correctly predicted the sequence, therefore it would have already happened, therefore the P=1 :-)

Oh, and Acer is right about the dependent and independent thing. If you have a population of 30 trees and one falls over, then the next probability scenario will only have a population of 29 trees, and the next will have 28 etc... This is also different to calculating the probability of all the trees falling over in a single event, or calculating the probability of all (or several) of the trees falling over in one year (or any other period of time), or there being several casualties from a single tree failure event. This is obviously of less concern when dealing with extremely large populations and rare events such as national tree populations and serious tree failure casualties, or where total population numbers are large but not accurately known (eg LA or estate tree populations). So tree failures in a limited population are different to coin tosses. :-)

I'm with Tony - it's already happened so the answer is P=1. I've just had a read through v5 practice note. Thanks for bringing it to my attention, it looks much better than previous versions. After reading practice note 5 I am very tempted to do a U-turn and sign up to QTRA (if you'll still have me), but I'd want a bit more info on how the calculations work first. Any chance of some info on the monte carlos method used? As for Tony's aside - are you sure you know someone who can accurately predict coin tosses as they happen? Or do you mean you know someone who can predict the probabilities of the results of coin tosses as they happen. I'm intrigued either way :-)

Yes, I can, but as someone who's not a registered QTRA user, what's in it for me? I don't want to be unhelpful when it's a matter of interest to wide range of arbs, or where questions are of a not for profit nature, but I get the impression that what you are trying to achieve here is solely for the monetary benefit of QTRA Ltd. BTW, and as an aside, has this new Monte Carlo method of tree risk assessment been peer reviewed?

Hello Yorkshireman, No, I know I'm not truely anonymous. But there's a difference between being known to just a few arbtalkers, and being known to all arbtalkers. Not that I've got any reason to hide, as you know.

If a debate is wanted about QTRA I suggest someone post some worked examples so we can all discuss it openly, but please let's do it on a seperate thread.

Excellent advice. Are you studying law Andy? I just ask because, looking at some your other posts, you seem to know quite a bit about it. Also, do you know any legal forums that are friendly to the legal layman?

Firstly, this is brilliant - the AA and the ISA trying to work together, it's very good to see. And if this results in a some kind of formal arrangement, then that has got to be good for arboriculture. Ian, I know the FC have a long, and very good, history of working with urban trees, but the problem is that there is no formal or properly acknowledged inclusion of arboriculture. I have a vague memory of funding being pulled from a major FC headed urban tree disease monitoring project - which was followed by a petition to 10 Downing street. The reply from Government was something along the lines that the FC should not be allocating its resources to amenity tree care. This reply would not have been possible if there was a formal inclusion of arboriculture in the FC's remit. I agree with you that the name is not really important, the disciplines of arboriculture and forestry are highly interchangable, especially in urban areas. So although I share John's desire for a 'tree commission', I think changing the remit of the FC to include arboriculture would suffice. Paul and Ian, I'm sure there are others who would be far better suited to the task, but if this is a cause you want to run with, I'd be happy to help. Paul, I'll send you an e-mail just in case you don't get this post.

It seems that under current spending reviews the structure and focus of the Forestry Commission is to be substantially reviewed. Might this be a good time to lobby for a more formal and properly acknowledged inclusion of arboriculture within the FC remit? If so, it would be good to see AA, ISA and ICF (and others) working together on this. Anyone have any thoughts?

Nice series of pictures, thanks for sharing. Just wondered what type of soil you've got. I've been lead to believe that airspades aren't so good on very heavy clay soil, but I'm hoping to be proved wrong.

Thanks Sloth, that makes more sense and sounds a bit more realistic than I thought at first.

Anyone brave enough to try Jelly Ear (don't like the name Jew's ear anymore now that I've realised how anti-semitic it is). I finally tried it after a couple of decades of thinking, "I'll try that one day." Surprisingly nice. Another surprise I had last year was that hogweed (not the giant type) is not only edible, but really nice if prepared properly.

Thanks for that Sloth. But without knowing what the questions were, I'm still not sure I understand. I've probably got the complete wrong end of the stick, but is the exam placing the arb in the position of someone who would be undertaking a site survey and then designing the layout of a site?

I'd say, as a member or past member of all three, that the AA, the ISA and the ICF are all worth joining for one reason or another. Couldn't say which was best though - it depends on what you are wanting for your money. I think if you have to choose one over the other it depends on what you want to do in the long term after you've finished your quals. Do other professions have a similar dilemma I wonder?