Bleeding Canker on the rise in UK
(October 2007)
The Forestry Commission has launched a Great Britain-wide survey of the number and distribution of horse chestnut trees and in particular to gauge the incidence and distribution of bleeding canker of horse chestnut, which has caused concern among tree owners and the public in recent years. The information gained from the surveys will inform any future advice offered to horse chestnut owners to help manage the impact of bleeding canker.
Roddie Burgess, the Commission's head of plant health, explained: "Horse chestnut trees are a much-loved feature of the British landscape, and we want to respond to public concern about their future by formulating management advice to tree owners, and we also need to learn as much as we can about the extent of the risk to horse chestnut and, if any, to other tree species.
"We've had a low level of incidence of bleeding canker of horse chestnut trees for 30 or 40 years that has been caused by two Phytophthora species: Phytophthora citricola and Phytophthora cactorum. The small numbers of affected trees and the low rate of infection meant this did not cause concern.
"However, over the past five years there has been a significant increase in the number of bleeding cankers reported on horse chestnut, but Phytophthora is now rarely the cause. Instead, another organism is the culprit, and scientists at our research agency, Forest Research, now believe the bacterium Pseudomonas syringae is responsible for the increased number of trees with bleeding canker.
"Until now we have been basing our figures on educated estimates extrapolated from the data that we do have. However, given the dramatic increase in the number of infections, we need a much more precise picture of the numbers and distribution of the trees and the infections in order to accurately gauge any possible risk to other species, and to be able to prepare high-quality management advice to tree owners.
"Accordingly, we would welcome information about the locations of horse chestnut trees from landowners, farmers, foresters, arboriculturists, local authority tree officers and others who are knowledgeable about trees, particularly in rural areas."
NOTES: Horse chestnut ( Aesculus hippocastanum ) is a native of the Balkans region of south-eastern Europe, and is believed to have been introduced to Britain in the 1500s.
