The disease is a more serious threat than leaf miner, which is disfiguring leaves and almost putting an end to trade in the tree, with a 98 per cent fall in sales over five years (HW, 2 September).
While the Cameraria ohridella leaf miner does not kill trees, canker does. The latest figures showed half of trees surveyed in 2007 were infected. Forest Research said infection rates were increasing by an unknown amount.
Forest Research pathologist Dr Sarah Green said: "We are focusing on several key aspects of the biology of the bacterium Pseudomonas syringae pathovar aesculi (Pae), which causes horse chestnut bleeding canker.
"Another focus of research is the possible resistance to Pae of some individual trees, following up anecdotal evidence that some trees have remained uninfected despite several near neighbours becoming heavily infected.
"Our research is looking at the genes the pathogen needs to infect the trees and, once we know that, we can look at why certain individual trees seem to be resistant. The potential benefit of this is that such trees could become the basis of future resistant planting stock".
Majestic Trees owner Steve McCurdy said a cure for bleeding canker was needed if sales of the tree were to recover.