Christian Ecology Link is launching a new campaign warning of that diseases from imported plants risk killing trees and plants across the UK.
"When seventeenth and eighteenth century plant hunters like Joseph Banks returned from long sea voyages to introduce new species to England, they little new the consequences of the trend they would inspire," the group said.
"During the years which have followed, the international plant trade has allowed many and diverse pests and diseases to cross the world."
Examples include the gall wasp, many of which attack oak trees and rose plants, Phytophtora - otherwise known as "sudden oak death" - which is causing problems in Scotland and Wales, and ash dieback caused by Chalara fraxinea, which is now resulting in widespread damage to ash trees in 16 counties across the UK.
CEL says that immediate action must be taken if the nation is to effectively address the situation before it escalates any further.
"In recent years the scale and rate of the problem has exploded as more and more new diseases develop," it claims.
CEL says Britain needs to increase the percentage of imported cargo that is inspected for disease – it currently stands at just two per cent.
However, it adds that individuals are able to make a difference too. It is calling upon gardeners to buy smaller, easier to manage trees rather than large ones, and to send a letter to their local garden centre or plant nursery asking them to sell only UK-grown or sourced plants in order to limit the introduction of invasive diseases and pests.
CEL hopes this will mean Britain's plant life will be able to flourish naturally, without the increased use of pesticides or other chemicals to keep new diseases at bay.
Further details and an example letter can be found at www.greenchristian.org