Ash dieback: native trees coming into Britain will have to show complete 'paper trail' But with a number of new diseases on the horizon Owen Paterson, the Environment Secretary, has ordered that all imports of oak, ash, sweet chestnut and plane trees must travel with documents showing where they are from originally. We need to ensure we have a healthy, thriving stock of our native trees and these controls will significantly help us to prevent pests and diseases from getting established in the first place. We have learnt from ash dieback how important it is to be able to act quickly to identify where infected trees may be," said Mr Paterson. There are currently 339 sites around the country infected with ash dieback, many are "recent plantings" where imported saplings could have bought in the infection. The disease is expected to spread further this year and could wipe out the country's ash population. Dr Simon Pryor, Director of the Natural Environment at the National Trust, welcomed the announcement. He said a number of other diseases from Europe, including sweet chestnut blight and plane wilt, are in danger of infecting the nation's trees unless imports are better controlled. This is a very welcome move, and exactly the sort of action that is needed to prevent more tree pests and diseases being imported into this country. We have been very worried about chestnut blight, and were on the brink of stopping any planting of this species on our own land as we couldn't be sure they weren't imported or infected. The extension of the inspections to cover a range of species gives us greater confidence. This move is particularly important as both oak and chestnut are species which might be appropriate to replace ash with once the extent of ash dieback is known.