More than 3,000 ancient trees in Sussex are under threat, tree experts have revealed.

Some of them have survived for more than 1,000 years but could die out due to a raft of diseases and pests.

The Woodland Trust revealed there are at least 15 knowndiseases and pests that pose an “immediate threat” in the county.

Brighton is home to the National Elm collection, with the world’s oldest English elms in Preston Park known as the Preston Park twins, both of which are ancient trees.

There is also an ancient elm tree in Royal Pavilion Gardens.

These historic trees are susceptible to the killer infection Dutch elm disease.

But that is not the only threat to the ancient, veteran or notable trees.

Ash trees may be at risk from the recent ash dieback/Chalara fraxinea outbreak.

There is also Acute oak decline and the oak processionary moth, Phytopthora kernoviae which affects oak and beech, and Dothistroma needle blight which affects Scots pine.

Ancient trees are described as the natural equivalent of listed buildings – they’ve stood for hundreds of years and witnessed historic events while watching silently in the background.

Austin Brady, head of conservation for the Woodland Trust, said: “Sussex has some fantastic examples of ancient trees and some of the finest can be seen at Petworth House, Ascombe Bottom and Eberknoe Common.”

Janyis Wilson, head of conservation at Sussex Wildlife Trust, added: “Ancient trees have been part of the Sussex landscape for centuries.

“They are hugely valuable in biodiversity homes providing food and shelter to a rich variety of organisms from the minute leaf miner to woodpeckers and owls.”

The Woodland Trust is holding a conference in June with some of the top minds in conservation, forestry and tree health to find a way forward for the country’s trees and woods.

It is asking for the public’s help by getting outdoors, looking at trees and checking them for signs of disease.

At this time of year one of the easiest ways to see if a tree is suffering from ash dieback is to look at a young branch and scratch a little of the bark off, if it is green underneath the tree is healthy, if it is brown it is not.

To find out more about spotting ash dieback and other tree diseases already present in the UK, or to record possible disease in an ancient tree near you, download the Tree Alert app or visit www.forestry.gov.uk/treealert.