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Ancient Tree ForumThe Tree Register

Hope in the battle against Ash Dieback – resistant propogation may hold the key

Results from a Swedish research study published in October 2012 offer some hope that Ash Dieback may be controllable, with the right breeding programmes.

The study, published in the Scandinavian Journal of Forest Research, assessed Ash Dieback damage on 16–22 year-old grafts in two ash seed orchards (Fraxinus excelsior L.). The grafts originated from 106 plus-tree clones selected from 27 stands in southern Sweden based on their phenotypes.

Ash Dieback lesions, www.tree.disease.co.uk

The results indicated that Ash Dieback disease is strongly genotypically controlled. There was considerable genotypic variation among individuals. None of the clones seemed to be totally resistant, but some exhibited reduced susceptibility and retained this resistance after six years under heavy infection pressure.

The paper reported that: “Autumn phenology based on leaf coloration was subject to moderate genetic control. The genetic correlation between autumn phenology and damage was weak to moderate and positive, indicating that susceptible clones have a prolonged growing season.”

And it concluded that as there was no evidence suggesting that stands differed in susceptibility. Together with high heritability of resistance, the researchers reported, strong correlations for specimens of the same age and weak interactions of genotype and environment suggested there is good scope for breeding less susceptible trees for the future.

The full paper can be found here.

Thanks to Kevin Coleman for the tip-off.