Thousands of horse chestnut trees are dying in what has been called the worst blight since Dutch Elm Disease.
Leaves have withered and turned brown on horse chestnuts in Kent
The conker trees, across London and the South East, have been affected by drought, the leaf miner moth and a bark fungus called bleeding canker.
One of the region's MEPs has called for EU-funded research into the canker.
Experts at the Royal Botanic Gardens, Kew, have compared the problem to Dutch Elm Disease, saying they do not want another species wiped out.
Dying trees in Chatham, Medway, are now set to be removed and replaced - signs of infection include brown leaves and few conkers on the trees.
Bleeding canker on the trunks means the bark underneath is dead
Michael Sankus, from Medway Council, said most would be removed and replaced with an alternative species, but officers were waiting to assess whether others could survive.
Joan Webber, from the Forestry Commission, told BBC South East Today that the canker was "more of an issue" than the parasite.
The leaf miner moth, which causes leaves to wither and fall, does not cause the death of the tree, but bleeding canker means the bark underneath is dead - and badly-affected trees may not recover.
Horticulturalists have suggested planting hybrids that are resistant to the canker, and also choosing different species that can also tolerate drier summers.
Latest figures reveal there are about 470,000 horse chestnut trees in Britain, of which 432,000 are in England.
Liberal Democrat MEP, Sharon Bowles, has called for research on how the trees can be protected, claiming about 40,000 to 50,000 trees across the country are currently affected.
She said: "Many experts warn that this outbreak could be as serious as the outbreak of Dutch Elm Disease."
Since Dutch Elm Disease hit Britain in the 1970s, the trees are now restricted on the south coast to a stronghold in the city of Brighton, where officers have managed to keep 15,000 elm cultivars and varieties alive.