Plants affected by "sudden oak death" in Cornwall are to be destroyed and parts of infected gardens cordoned off under new government measures.
Death is inevitable if the fungus strikes (Image: Forestry Commission)
Nine British trees have been affected by the disease which has destroyed thousands of acres of woodland in the United States.
Environment minister Ben Bradshaw is introducing border controls to prevent a similar disaster in Britain.
He fears it could become a worse problem than Dutch elm disease.
"The evidence from California and the [rest of the] US is that it has ravaged 80% of their native oaks, and we don't want to see that happening here to our native beech, chestnut and other trees," he said.
The disease is caused by a fungus, known as Phytophthora ramorum.
Three disease sites have been identified in Cornwall, and at each one it is thought the fungus has spread to trees from rhododendron bushes.
At the Lost Gardens of Heligan, rhododendrons are being controversially burned under the orders of the Department for Environment, Food and Rural Affairs (Defra) because it says the plants showed signs of the disease.
Mr Bradshaw defended the action, saying the host plants for the disease in this country were rhododendrons and other non-native, imported shrubs, which tended to be found in many historic gardens and nurseries.
"That's where it has been found and it is important we take tough measures now to prevent the disease spreading outside those gardens and into our native woodland."
Scientists gathered at St Austell Brewery on Tuesday to discuss measures to stop the spread of the disease.
Mr Bradshaw said this provided an opportunity for local garden owners and the community to engage with Defra and the Forestry Commission on what they were doing about the disease and the measures that needed to be taken.
"If we act quickly we can contain and eradicate this disease, but if we don't we will lose the battle," he said.
The native English oak (Quercus robur) is strangely not susceptible to the disease, although other popular trees like beeches, conifers, spruces and firs are.
Dying leaves are a classic sign of sudden oak death, but more advanced symptoms include the blistering of the trunk.