Serious threat to Hawthorn in hedgerows
FIREBLIGHT is a plant disease that poses a serious threat to our hedgerows and fruit crops. The Department of Agriculture, Food and the Marine has confirmed that last year there were 17 outbreaks in Ireland across 11 counties.
The disease’s name is based on two misconceptions. The ‘blight’ part of the name implies that the disease is a fungus like Potato Blight; but it is caused by a bacterium, a species named Erwinia amylovora. Bacteria kill the infected plant and when it dies the dead blackened leaves stay attached giving the impression that the plant has been scorched by fire, hence fire-blight.
The disease is native to North America. It spread to Europe during the 1950s and is now reported to be widespread throughout the European Union. It was first reported in Ireland in 1986 and isolated outbreaks were initially controlled and eradicated.
The disease in incurable. The only known way to control its spread at present is to destroy an infected plant and to set up a quarantine buffer zone around the outbreak.
Fireblight is a disease of several members of the large rose family. It kills wild plants like Hawthorn, street trees like Mountain Ash, garden shrubs like Cotoneaster and Pyracantha, and fruit trees like apples and pears. Some species, varieties, and cultivars are highly susceptible to being infected while others are less so. Some species are said to be immune.
Fireblight symptoms include wilting and death of flower clusters following blossom infection. Infected young shoots wither and die. In some cases, the tip of the shoot bends to form a characteristic ‘shepherd’s crook’. Infected leaves show dead patches, which spread. Infected fruit turns brown or black and shrivels but remains attached to the plant. Bark can degrade, sink, crack, and ooze.
Bacterial oozes on an infected plant can spread bacteria to other plants via wind, rain, insects, and birds.
For further information and possible actions see Hedgerows Ireland webpage at https://hedgerows.ie/fireblight/?mc_cid=bc97f08e21&mc_eid=efb1fd35d0. If you find suspected symptoms or specimens, please submit details and images to the Department of Agriculture, Food and the Marine at plantsandpests@agriculture.gov.ie.