UKTC Archive

Re: Dead, Dying, Dangerous Query

Subject: Re: Dead, Dying, Dangerous Query
From: Adam Hollis
Date: Jun 04 2006 08:09:46

On 3 Jun 2006, at 22:26, uktc-request@xxxxxx.tree-care.info wrote:

Date: Sat, 3 Jun 2006 13:33:31 +0100
From: "Mike Ellison" <mike@xxxxx.co.uk>
Subject: RE: Dead, Dying, Dangerous Query

Hi Scott

SC - I did see some research from Western US that stumps can provide a
massive food source for aggressive Armillaria sp. (I'd guess mellea but not sure) and that infection areas obviously spread from cleared areas (e.g.
blowdown patches) where stumps had been left.

ME - Well that is my point.  When we know that the fungus decays
non-functional xylem, it doesn't take much or any research to conclude that
the fungus will decay dead stumps.

SC - No doubt there are many other variables involved and I'm sure you have to be familiar with local host/pathogen/climate/soils relationships to know
when it matters.

ME - It seems to matter particularly where there are environmental stresses
resulting from disturbance (clear felling and extraction) and reduced
biodiversity. I guess that escalating organised crime in Eastern Europe
following disturbance of a social equilibrium is a reasonable analogy.


Mike


Mike

Hi

I agree with you in principle, but Hetero b. may be one of the exceptions to the rule.

Your analogy perhaps applies more readily to r-strategy pests which continually colonise habitat of an ephemeral nature or exploit rapid changes in their environments; e.g. bacterial cankers of poplars in forest monocultures and cereal rusts in prairie agriculture.

However, Hetero b. is a K-strategist which likes more stable conditions and narrow niches - a specialist. As such, it is more vulnerable to cultural controls. Just as debarking felled trees can eliminate the potential breeding grounds for bark beetles, so removal of Hetero b.-infected stumps can substantially reduce the risk of infection to the next crop.

See Conway, G (1981). Man versus pests. In Theoretical Ecology (2nd ed) (ed. R. M. May,), pp. 356-86. Blackwell Scientific Publications, Oxford.

I grant you, my references may be out of date.

The other key issue we were taught in forestry, was correct species/ provenance choice. Most of the really dreadful problems were caused by wrong choices, rather than necessarily, monocultures; e.g. wrong provenance of lodgepole pine on unflushed peat in Scotland resulted in devastating outbreaks of pine beauty moth in th elate seventies/ early eighties.

Anyway, time to get out in all that sunshine - I'm off for a pic nic breakfast in a beech monoculture!

Regards

Adam

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