horse chestnut bleeding canker

[arb culture]

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

[AA Teccie (Paul)]

Not aware of any updates 'per se' on how to deal with the disease but, anecdotally, many contractors, and some consultants, are telling me trees previously infected appear to be recovering.

 

Hence it may be much to do with individual tree vitality so avoid any additional stress factors including excessive pruning.

 

Cheers..

Paul

[arb culture]

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 :-(

[AA Teccie (Paul)]

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 :-(

 

Forest Research - Specific recommendations for the management of bleeding canker of horse chestnut provides some 'more specific' advice which may be of help / interest.

 

In practice, whilst burning of infected material on site etc. is probably the recommendation action, and I wouldn't say this if it was Chalara of Ash, many HCs are chipped and transported. I think it's what you do with it thereafter that can result in, or avoid, problems, i.e. spreading around other HCs trees or composting the woodchip and burning the logs.

 

cheers..

Paul

 

PS Don't forget about tool sterilisation too, which is a good practice thing. I think the FC generally recommend a product called 'Propellar' but many use Jeyes Fluid.

[daltontrees]

The FC advice seems sound. But basically the disease comes down to miniscule individual bcateria which like the common cold are effectively ubiquitous. It would ionly take one bacterium on one fly's leg and that fly to move form one tree to another to look for a bark crevice to lay its eggs in and then you have the formula for infection.

 

You can't stop infection but you can avoid the things that will very obviously help it, like dirty tools. Since the precise vectors for the spread of teh disease is not known, equally it is not known whether airborne infection is possible or likely (such as chipping would encourage), but if insects are involved then evicting them at maturity will probably encourage spread. Removal in winter can only help reduce spread.

[arb culture]

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

[arb culture]

Update: I have been informed that Potassium phosphite can be used to help infected trees if it is used as a fertiliser.

 

Does anyone know more about this?

[AA Teccie (Paul)]

Update: I have been informed that Potassium phosphite can be used to help infected trees if it is used as a fertiliser.

 

Does anyone know more about this?

 

I know that Bartletts (Glynn Percival) has done quite a lot with Phosphites for HC BC and had quite good results.

 

See the attached for more info.

Managing-Pseudomonas-Bleeding-Canker-of-Horse-Chestnut.pdf

[arb culture]

Cool, thanks Paul.

 

[Paul Cleaver]

I know that Bartletts (Glynn Percival) has done quite a lot with Phosphites for HC BC and had quite good results.

 

See the attached for more info.

 

good info -