DNA testing could help track deadly Chalara ash disease
DNA technology is being field-tested in Norfolk as part of the continuing effort to diagnose trees infected with the Chalara ash dieback infection, which has taken root in East Anglia.
The outbreak of the disease sparked a major national crisis-management effort after it was confirmed for the first time in the wild in Norfolk last October.
But the winter has provided a respite from the spread of the fungal disease, as it is believed to be carried on spores produced from infected dead leaves between June and September.
Forestry Commission (FC) plant health experts are taking advantage of this lull to test and calibrate four portable DNA machines which could help improve our knowledge about the pathogen which has devastated ash woods in mainland Europe.
The OptiGene “Genie II” machines, which cost about £8,000 each, can process up to six samples at a time and allow the teams to quickly tell if the disease, also known as Chalara fraxinea, is present. Samples take about an hour to prepare and the results can be seen after about half an hour.
Ben Jones, the Forestry Commission’s plant health operations manager, said: “Being able to test samples quickly and accurately will be a great help in tracking and managing tree diseases.
“It means that our team can take samples of suspected infected ash trees especially on sites where symptoms are subtle, take them to a local FC office and within a very short time have accurate DNA results to be able to tell the woodland owner. Of course Chalara is just one of a number of pathogens that affect our trees and woodlands and in the future we are hopeful that we can use this kit to identify those as well.”
To test and calibrate the machines, specialists have been taking samples from known infected sites belonging to Norfolk Wildlife Trust, which are then sent to Defra’s research laboratories in York for validation.
If the validation is successful, forestry officials hope the Genie machines will become a standard piece of equipment for the plant health team.
Latest FC figures show 166 recorded cases in established woodland – mostly in East Anglia – which has now exceeded the number of cases in recently-planted trees imported from infected stocks in Europe.
In total, there are now 339 confirmed sites, spreading up the east coast from Kent to Scotland, and stretching as far west as Berkshire.
Significant casualties include Norfolk Wildlife Trust’s Wayland Wood, near Watton, and Lower Wood in Ashwellthorpe – where the first case was discovered in mature trees.
In November, an action plan was set out by environment secretary Owen Paterson which included tracing and destroying newly-planted diseased trees in nurseries, while preserving mature wild trees which are valuable to wildlife and take longer to die. Research surveys were also directed to look for signs of genetic resistance to Chalara.
Steve Scott, the Forestry Commission’s forest services director in the East, said: “Chalara is not that visible in the winter and is not spreading at the moment.
“We will continue to investigate the imported planted stocks, and we will continue to respond to any more sightings in the wild, particularly around the fringes of the known area and to fill any gaps. We don’t think we will see any changes on that map over the winter, so our plant health people are using that lull to use this new kit which gives them a very fast response in the field.”
For more information on Chalara, see www.forestry.gov.uk/chalara.