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Thoughts on Ash

Updated: Dec 19, 2019


Since the later part of 2012 the importation and movement of all Fraxinus (ash) species throughout the UK has been banned. A once very popular, native British tree (F. excelsior) is now effectively limited to where it seeds itself. Curiously, the ban extends only to those areas that have not be declared clear of the presence of the disease affecting this Genus. Perversely, no areas have yet been declared clear of the disease and the likelihood is that this won't ever happen. As a result, the tree remains in limbo.

The reason for the ban on movement is a sensible one. It aims to reduce the potential further spreading of Ash Dieback Disease, caused by a Fungus formerly known as Chalara fraxinea (now, Hymenoscyphus fraxineus) throughout the British Isles. Though only formally identified in the UK in 2012, it seems likely that it has been present without being overly destructive in the UK for at least a decade prior to this.

The European strategy is to prevent the spread of this and other diseases is sensible, but to my mind overly limiting and needs to be backed up with science. There are three things to consider as I see it with this and all similar plant disease issues. The first is to look for resistant plants and work with them in terms of production of resistant stocks and at a genetic level. The second is to look for a cure that kills the fungus. Finally, the third is to establish a disease free zone to move towards the future reintroduction of the Genus. Resources as always are limited, but my personal approach to an issue like this is to look for resistance in plants already in the ground here in the UK. So often in plants, time and exposure encourage adaptation within a reasonably quick cycle. Fraxinus is a good Genus to test on as they mature very quickly. If you were looking to find adaptive plants of Ginkgo for example, it could take hundreds of years to get through just a few generations. Ash can become mature enough to bear seed within just a handful of years from being a seedling itself.

My strategy to ensure continued survival of this great British tree is to look for plants showing resistance, collect seed from these plants and trial second generation plants roguing out plants that are affected by the fungus until (after several - many generations) we have a fully resistant seed selection of Ash that can be used safely. Obviously, this is a huge over-simplification of the process and the issue and like I said earlier, resources are tight, but worth investing in. This would unfortunately only resolve the issue within the species and not cultivated forms in existence, so could only ever be part of the bigger picture, but an important part in terms of our native flora.

Thankfully, science hasn't ignored the problem and a project has been working on exactly this since the disease was announced. In 2016 the first naturally tolerant Ash tree, showing resistance to Ash Dieback was discovered in UK, which in time could and really should lead to the resurrection of this once prominent tree. Here is a link to this article

In recent years, we have had more and more in the way of pest and disease related limitations to our plant options and we should all be concerned about this going forward. My feelings towards limits imposed on importation of plants that originate elsewhere in the world are mixed, but I am concerned and increasingly so when our native plants are no longer free for use.

We all must continue to show our appreciation for the value of our native flora and as an industry work with Defra, The Forestry Commission and the various research bodies working towards a solution rather than simply enduring a ban and waiting, ever hopefully, for good news.

iPlantsman

Defra Website link on Ash Dieback

Forestry Commission link on Ash Dieback

#Fraxinus #ash #tree #Chalara #disease #dieback #plants #native

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