English elms once roamed the British landscape, perhaps that's why they got that name. However surprisingly, English elms may have been introduced to the UK by Bronze Age farmers, or could be native to southern England only. Now they are much less seen, only when you are lucky you can find them in hedgerows or woodland. Very few mature trees are left. **Where have they all gone?
More than 30 millions** of native elm trees in the UK were killed by a deadly disease called Dutch elm disease, which arrived in the UK in the 1960s. The pathogen is a microscopic fungus called Ophiostoma ulmi, which starves the tree of water and nutrients. It is known as a die-back: the leaves wilt and turn brown first, then the shoots. These microfungi are carried by beetles which feed on the elm trees.
<aside> 💡 It became a global pandemic. Read the information board to learn how the pandemic started and why it spread so easily.
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Dutch elm disease is still a sustained threat to plant health and it will probably keep lingering for years. Elms can regrow from seeds and rootstock naturally or artificially, but they are likely to be infected with the disease before they reach maturity.
Besides Dutch elm disease, there are actually many emerging plant diseases that are getting attention. Some of the most devastating ones are: Ramorum larch disease, oak decline, and ash dieback.
<aside> 💡 Ask dieback costed £15 billion in Britain. The economic cost to plant disease is huge: it took time and money to grow and manage these trees, and these trees were of value to produce goods and timber.
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Plant scientists at Oxford are studying these diseases and are coming up with ways to develop resistance in these trees to stop these pandemics.
Oxford was particularly affected by the disease as it used to house many ancient elms. Now many of them are gone. These include the ones in Christ Church, Magdalen College, and Parks Road. The annual Magdalen College garden play used to take place in a circle of elms in the deer park before the trees fell to the disease.
<aside> 💡 Look at those photos and memories of elms on the information board. Think about how nature is well-tied with humanities. They are the keepers of our history, traditions, and culture.
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Harcourt Arboretum keeps some elm trees alive so they can be used to cultivate resistance and raise awareness of plant health.
Two research groups in Oxford that have a strong focus on tree health are led by Gail Preston and John MacKay respectively. Watch Julianna Piat's vlog on Dutch elm disease as part of the outreach project of The British Society for Plant Pathology.
https://www.youtube.com/watch?v=sEi50YfbqNw&feature=emb_title