Christmas trees under threat from new mould discovered in a lab

10 Dec 2019

Image: © Lee/

Scientists accidentally discovered a new type of water mould that could threaten the future of Christmas trees.

One of the most famous Christmas traditions is under threat from a type of mould that, until recently, no one knew existed. In a paper published to the journal Plant Disease, scientists in the US revealed that while working on ways to grow healthier Fraser firs – one of the species used for Christmas trees – they discovered something unexpected: a new destructive mould.

While rich in colour and scent, fir trees are highly susceptible to devastating root rot diseases caused by water moulds in the genus Phytophthora. Testing confirmed that the mould found on these Fraser firs was indeed a new species of Phytophthora and could seriously threaten the tree in the future.

“Once the organism was isolated, the presence of unusually thick spore walls alerted us that this may not be a commonly encountered species,” said Rich Cowles, a scientist at the Connecticut Agricultural Experiment Station involved with this study.

“Comparison of several genes’ sequences with known Phytophthora species was used to discover how our unknown was related to other, previously described species.”

The fact that the researchers were able to readily discover a new species of the mould suggests that there could be many more species waiting to be discovered. Transportation of infected nursery stock and chance encounters of different Phytophthora species in the field can lead to new hybrids arising, they said, which can have different pathogenic characteristics than their parent species.

“Knowing how many and which species are present is important, not only for Christmas tree growers, but also for protecting our natural environment,” Cowles added.

Fraser firs are not the only tree species under threat, with research published in September revealing that many native trees in Europe are in danger.

The European Red List of trees, which covers all 454 species of native trees, found that more than two-fifths – 168 species – are under threat of dying out in Europe. More than half (58pc) of the trees that are endemic – which are only found in Europe – are under threat, the assessment shows.

Colm Gorey was a senior journalist with Silicon Republic