Is Elm making a comeback or is it just a fairytale?

[hedgesparrow]

looked at the elms i have and looks as if two out of 4 have got it all the bark falling off so sad as i looked after them. now only good for firewood.

[JonnyVine]

looked at the elms i have and looks as if two out of 4 have got it all the bark falling off so sad as i looked after them. now only good for firewood.

 

Damn, you must be gutted!

 

I have a few on my land and every year I always fear the worst. I believe that trees are susceptible when the bark is of a sufficient thickness for the female scolytus beetle to lay their eggs in late summer. The beetles lay their eggs in galleries which they excavate between the bark and the wood carrying the spores of the fungus Ophiostoma novo-ulmi on their boddies.

The fungus then sporulates in these breeding galleries and the larvae which hatch from the eggs feed by extending them, (which can be seen as hundreds of squiggly lines when the dead bark falls off), the larvae pupate in the outer sapwood and and develop into young beetles which emerge the following spring and eat their way out of the bark leaving hundreds of small emergence holes.

The young then fly off carrying the spores of O. novo-ulmi on their boddies and begin feeding in the twig crotches on young bark wher the spores become lodged and begin to germinate.

The fungus grows in the xylem vessels (not the phloem) where it produces more of the yeast like spores and as the fungus moves through the xylem vessels it produces phtytotoxins that disrupt the trees metabolism. Phenol based substances are then formed in the vessels preventing the uptake of water and nutrients and the tree is now dying.

 

As already pointed out, Elm disease has been around for centuries in the form of Ophiostoma ulmi, which all but the weakest trees could tollerate, however in the last century a more aggressive strain known as O. novo-ulmi appeared and wiped out our native trees.

 

Susceptible species to the more aggressive O. Novo-ulmi are Ulmus procera (English elm), U. Hollandica ( Dutch elm) and U. carpinifolia var. sarniensis (Wheatley elm).

U. Glabra (Wych elm) and some spp of U. carpinifolia ( smooth leaved elm) are less susceptible and if infected, die over a longer period of time.

 

Interestingly, the gene that is affected by U. novo-ulmi has been identified and Anti-fungal DNA has been inserted into the Elm genome using coat

ed micro ball bearings! Unfortunately, present Law governing geneticaly modified crops prevents it from being implemented outside the lab and Personaly, I find this unfair as the female of the species is infertile so cannot be corrupted by pollen from GM trees.

Edited January 17, 2013 by JonnyVine

[Graham]

Here's an interesting example. An English elm of approx 80-90 feet.

 

The hedge along this lane is predominately elm. At one time there were big standards along the lane and a small wood adjoining a few hundred yards away which comprised mainly elm. These all succumbed to DED in the 70s and 80s yet this one still stands. Every year I wait with trepidation for signs.

 

[hedgesparrow]

Damn, you must be gutted!

 

I have a few on my land and every year I always fear the worst. I believe that trees are susceptible when the bark is of a sufficient thickness for the female scolytus beetle to lay their eggs in late summer. The beetles lay their eggs in galleries which they excavate between the bark and the wood carrying the spores of the fungus Ophiostoma novo-ulmi on their boddies.

The fungus then sporulates in these breeding galleries and the larvae which hatch from the eggs feed by extending them, (which can be seen as hundreds of squiggly lines when the dead bark falls off), the larvae pupate in the outer sapwood and and develop into young beetles which emerge the following spring and eat their way out of the bark leaving hundreds of small emergence holes.

The young then fly off carrying the spores of O. novo-ulmi on their boddies and begin feeding in the twig crotches on young bark wher the spores become lodged and begin to germinate.

The fungus grows in the xylem vessels (not the phloem) where it produces more of the yeast like spores and as the fungus moves through the xylem vessels it produces phtytotoxins that disrupt the trees metabolism. Phenol based substances are then formed in the vessels preventing the uptake of water and nutrients and the tree is now dying.

 

As already pointed out, Elm disease has been around for centuries in the form of Ophiostoma ulmi, which all but the weakest trees could tollerate, however in the last century a more aggressive strain known as O. novo-ulmi appeared and wiped out our native trees.

 

Susceptible species to the more aggressive O. Novo-ulmi are Ulmus procera (English elm), U. Hollandica ( Dutch elm) and U. carpinifolia var. sarniensis (Wheatley elm).

U. Glabra (Wych elm) and some spp of U. carpinifolia ( smooth leaved elm) are less susceptible and if infected, die over a longer period of time.

 

Interestingly, the gene that is affected by U. novo-ulmi has been identified and Anti-fungal DNA has been inserted into the Elm genome using coat

ed micro ball bearings! Unfortunately, present Law governing geneticaly modified crops prevents it from being implemented outside the lab and Personaly, I find this unfair as the female of the species is infertile so cannot be corrupted by pollen from GM trees.

what you say sounds right under bark is wavy white spore like lines so it is ded. what happens to larva and beetle in winter do they live in the tree. and is there no chemical you can use to spray to kill the critters off one of the trees is just getting to a nice size. i hate to see it get this. would winter tar oil sprayed on trunk stop them.

[nepia]

[quote=jonny.;Susceptible species to the more aggressive O. Novo-ulmi are Ulmus procera (English elm), U. Hollandica ( Dutch elm) and U. carpinifolia var. sarniensis (Wheatley elm).

 

 

Interesting as yesterday I scrapped a 10" sucker of what the T.O. told me was hollandica, the 20+"dbh parent being some feet away and last year at least was in rude health. I was given to understand that its success was due to hollandica's resistance to DED.

This is in deepest suburbia near Epsom.

 

Jon

[Daniël Bos]

what you say sounds right under bark is wavy white spore like lines so it is ded. what happens to larva and beetle in winter do they live in the tree. and is there no chemical you can use to spray to kill the critters off one of the trees is just getting to a nice size. i hate to see it get this. would winter tar oil sprayed on trunk stop them.

 

You may be able to stop the beetles (though unlikely) but the fungus is there and has done its deed by the sounds of it so not much point.

[likeitorlumpit]

I remember doing a talk on DED in 1979

There was an innoculation that I think Brighton used. Can't remember the name of it. Useful I'm not.

[JonnyVine]

what you say sounds right under bark is wavy white spore like lines so it is ded. what happens to larva and beetle in winter do they live in the tree. and is there no chemical you can use to spray to kill the critters off one of the trees is just getting to a nice size. i hate to see it get this. would winter tar oil sprayed on trunk stop them.

 

Hi

There is a treatment which involves injecting a fungicide, however its aplication is extremely complicated so quite hit and miss and can bring about its own complications.

[JonnyVine]

Here's an interesting example. An English elm of approx 80-90 feet.

 

The hedge along this lane is predominately elm. At one time there were big standards along the lane and a small wood adjoining a few hundred yards away which comprised mainly elm. These all succumbed to DED in the 70s and 80s yet this one still stands. Every year I wait with trepidation for signs.

 

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Wow, what a bute, nature just beggars belief

[HCR]

U. Glabra (Wych elm) and some spp of U. carpinifolia ( smooth leaved elm) are less susceptible and if infected, die over a longer period of time.

 

Interesting - my understanding (which may well be wrong, I'm making no assertions) is that U glabra is to some extent protected from infection by the form of its bark - i.e. it's less attractive to the female beetle - but once infected, succumbs relatively quickly.

 

Natural selection article for sciency types - I found it very interesting:

 

Maximum Entropy: Natural Selection By Proxy)