elms remaining

[likeitorlumpit]

Have been asked to look at a 35 year old elm (twisted) today that they think has DED. In sussex

My thoughts were really how decimated is the elm population- there are none round here although I know Brighton has a few- control zone.

Is there anywhere that elms are thriving naturally?

[agg221]

Yes, round here.

 

I think it's because most English Elm were propagated by suckers, so the genetic stock is very small. Round here we get a lot of hybridization with the Plot Elm, which is fertile, so the genetic stock is much broader. There are a modest number of reasonable sized trees, some of which seem to be able to shake it off after an attack. I know of at least 15 trees of over 2ft dia. in areas where the non-resistant ones are dying off, sometimes right next to them, so there's no chance they're not exposed.

 

Alec

[defenderjack]

Have been asked to look at a 35 year old elm (twisted) today that they think has DED. In sussex

My thoughts were really how decimated is the elm population- there are none round here although I know Brighton has a few- control zone.

Is there anywhere that elms are thriving naturally?

 

round sussex i reckon this year is one of the worst weve had for a while , weve been working with east sussex and i reckon weve felled nearly 80 good sized elms in 3/4 weeks

some were on the list as the oldest 200 + in wilmington, 20 trees came out of that tiny village alone and it looks so empty now , i know ive had enough of bonfires in this heat now !thats for sure !

[tim361]

The company I work for is based in Eastbourne and they're getting none stop calls from the council to take down elms in Eastbourne. This year seems to be one of the worst for Dutch elm in recent years. Give it 2-3 years and they'll be none left in Eastbourne.

[likeitorlumpit]

Yes, round here.

 

I think it's because most English Elm were propagated by suckers, so the genetic stock is very small. Round here we get a lot of hybridization with the Plot Elm, which is fertile, so the genetic stock is much broader. There are a modest number of reasonable sized trees, some of which seem to be able to shake it off after an attack. I know of at least 15 trees of over 2ft dia. in areas where the non-resistant ones are dying off, sometimes right next to them, so there's no chance they're not exposed.

 

Alec

 

Thats heartening news-and

I hadn't considered vegetative propogation as a reason that whole populations go down- so seed is a source of biodiversity.

Now we have micropropagation techniques- this may lead to further population crashes(all same genetic stock)

So our diversity is our strength-mmmmm

[agg221]

Genetic diversity vs. micropropagation is a challenge. Specifically as applied to elms my personal view is that whilst there are a reasonable number of trees left they often go unnoticed - try finding any links to the ones in Haverhill for example, the only source is knowing to look on Google Streetview! They are therefore at risk from many other threats - old age, development etc. and the population of resistant trees is therefore likely to be in decline.

 

If the spacing between resistant trees exceeds a critical threshold it is likely that they will fail to sexually reproduce and the genetic resistance will be lost to the gene pool.

 

In the above situation, propagation of apparently resistant trees represents a sensible move, to maintain the gene pool and ensure sufficient population to ensure sexual reproduction.

 

My personal view is that there is a sensible series of projects to be carried out here. The first move is to document surviving trees of any size. In the US, screening techniques have been developed to confirm resistance based on exposing tissue to DED and studying the effect - a similar approach here would confirm which trees have survived through resistance and which through chance or geography. Propagating and distributing the resistant trees would then enhance the likelihood of maintaining natural propagation of genetic stock in the future.

 

Unfortunately, whilst two of the above activities are underway - there is a national survey and a number of piecemeal propagation programmes for surviving trees, the missing link is the genetic resistance testing, which is key to ensuring that the efforts are not wasted.

 

Anyway, not having access to the necessary screening capability, I am guilty of the 'propagate and hope' approach!

 

Alec

[likeitorlumpit]

Genetic diversity vs. micropropagation is a challenge. Specifically as applied to elms my personal view is that whilst there are a reasonable number of trees left they often go unnoticed - try finding any links to the ones in Haverhill for example, the only source is knowing to look on Google Streetview! They are therefore at risk from many other threats - old age, development etc. and the population of resistant trees is therefore likely to be in decline.

 

If the spacing between resistant trees exceeds a critical threshold it is likely that they will fail to sexually reproduce and the genetic resistance will be lost to the gene pool.

 

In the above situation, propagation of apparently resistant trees represents a sensible move, to maintain the gene pool and ensure sufficient population to ensure sexual reproduction.

 

My personal view is that there is a sensible series of projects to be carried out here. The first move is to document surviving trees of any size. In the US, screening techniques have been developed to confirm resistance based on exposing tissue to DED and studying the effect - a similar approach here would confirm which trees have survived through resistance and which through chance or geography. Propagating and distributing the resistant trees would then enhance the likelihood of maintaining natural propagation of genetic stock in the future.

 

Unfortunately, whilst two of the above activities are underway - there is a national survey and a number of piecemeal propagation programmes for surviving trees, the missing link is the genetic resistance testing, which is key to ensuring that the efforts are not wasted.

 

Anyway, not having access to the necessary screening capability, I am guilty of the 'propagate and hope' approach!

 

Alec

Equally- propagation to increase populations of resistant trees may if conducted vegetatively or microprop(same thing really) will lead to genetically identical stock which may fall to a future pathogen(as yet unknown) though be fantastically resistant to DED

So.. how do we build resistant stocks with a diverse gene pool

Or do we just let nature get on with it-= this I favour:thumbup:

Is Brighton council making a mistake trying to preserve a failing species?

[agg221]

Equally- propagation to increase populations of resistant trees may if conducted vegetatively or microprop(same thing really) will lead to genetically identical stock which may fall to a future pathogen(as yet unknown) though be fantastically resistant to DED

So.. how do we build resistant stocks with a diverse gene pool

Or do we just let nature get on with it-= this I favour:thumbup:

Is Brighton council making a mistake trying to preserve a failing species?

 

My view is that man created the problem and hence man should take a hand in trying to fix it. I don't think Brighton council's approach is long-term sustainable, although I applaud their efforts. I also don't think the species will necessarily fail, although I agree that simply vegetatively reproducing a stock would leave it exposed to other pathogens.

 

The approach I favour is similar to that of other re-introductions, which are usually based on breeding up a sufficient population (in this case likely to be by microprop) to ensure a breeding population in the wild which can then diversify further.

 

For example, if you took a hypothetical 50 resistant trees, propagated them and introduced a couple of each within a square mile area, it's likely that those hundred trees would produce offspring with an enormously diverse range of characteristics. If allowed to simply reproduce naturally, they would be capable of producing millions of offspring per year. These would include both resistant and non-resistant characteristics. The latter would die at an early age, but the range of resistant population would still be enormous.

 

Of those hypothetical 50 resistant trees, I could probably make a start with at least five genetically different populations, possibly as many as eight, so I think it's realistic.

 

Alec

[likeitorlumpit]

My view is that man created the problem and hence man should take a hand in trying to fix it. I don't think Brighton council's approach is long-term sustainable, although I applaud their efforts. I also don't think the species will necessarily fail, although I agree that simply vegetatively reproducing a stock would leave it exposed to other pathogens.

 

The approach I favour is similar to that of other re-introductions, which are usually based on breeding up a sufficient population (in this case likely to be by microprop) to ensure a breeding population in the wild which can then diversify further.

 

For example, if you took a hypothetical 50 resistant trees, propagated them and introduced a couple of each within a square mile area, it's likely that those hundred trees would produce offspring with an enormously diverse range of characteristics. If allowed to simply reproduce naturally, they would be capable of producing millions of offspring per year. These would include both resistant and non-resistant characteristics. The latter would die at an early age, but the range of resistant population would still be enormous.

 

Of those hypothetical 50 resistant trees, I could probably make a start with at least five genetically different populations, possibly as many as eight, so I think it's realistic.

 

Alec

 

Good point- I forgot the resistant trees would confer some resistance to the natives

Yea- give elms a chance- I rather like the way they grow

[agg221]

I have a particular connection with elms, as one of my earliest memories is of seeing them dying. I specifically remember an occasion when visiting my grandparents on the Isle of Grain, aged about 3, and noticing that the row of trees on our regular walk was suddenly gone, and all that was left was a row of enormous stumps.

 

This was probably the very start of my interest in trees.

 

The elms were formerly so ubiquitous and the decimation seemed so complete that I never had any expectation that I would see a landscape with elms again. The fact that I found the ones in this area a few years back, and now have every expectation that they will still be there in a few years when my daughters are old enough to notice them is something I would like to keep going.

 

Alec