Horticulturalists in the South West fear some of the region's most important gardens could be devastated because of government measures to prevent the spread of a disease in oak trees.
Plants are being burned at the Lost Gardens of Heligan
The Department for Environment, Food and Rural Affairs (Defra) is ordering the destruction of hundreds of rhododendrons, which it says could be carrying sudden oak death disease.
Rhododendrons at the Lost Gardens of Heligan are some of the plants now being burned on Defra's orders.
Inspectors looking for signs of Sudden Oak Death disease said the plants showed signs of the fungus that carries it and must be destroyed.
The Lost Gardens were only rediscovered in 1990 and staff there fear rhododendron plants 150 years old could be lost forever
Defra says the disease has devastated oak forests in parts of the United States and, although the fungus has not yet been found in any English oaks, the aim is to prevent it taking hold in the UK.
The department says an extensive survey is being conducted to trace the presence of the organism and eradicate it wherever its found.
But many refuse to accept the scientific basis of the policy and believe gardens could be decimated without proper justification
"The so-called disease they're finding is already endemic in Cornish gardens," said Charles Williams of the British Rhododendron Society.
"It has been endemic in Cornish gardens for a great length of time and therefore the enormous excitement and worry that Defra has been exhibiting through its enforcement notices is a futile response to a non-existent problem."
Defra says the policy has the backing of senior plant health experts in the European Union.
It has said the issue will be re-examined in the autumn after consultation with growers and horticulturalists.