Professor Oliver Rackham, a Life Fellow at Cambridge University, said that the “tree-planting” craze began in the 1970s with the campaign “Plant a tree in ‘73”. More recently private and public authorities have been encouraged to plant trees to help tackle climate change.

But the Professor of Ecology said tree planting has become too commercialised.

He said councils and other large organisations look for the cheapest trees available, that are often grown abroad. They then use contractors that are not experienced in planting the trees correctly.

He said many of the recent diseases that have hit the UK came in on imported trees and spread faster because the trees were planted too close together and weakened by lack of care.

“A lot of material – although it is of British origin – is grown overseas and brings foreign soil and what foreign soil contains,” he said.