Season three of Words on Wood kicks off with an exploration of tree diseases through the lens of ash, looking into the risks posed to this tree species across North America and Europe by the invasive emerald ash borer insect and the fungus responsible for ash dieback disease. How do these threats spread through forests and affect timber and, once they have struck, what happens to the dead and dying trees? We speak to Sheridan Coakley, founder of SCP Furniture, about the recent One Tree project, challenging designers to create a piece using a felled tree suffering with ash dieback, and Emma Hudgins - an expert on invasive species.