Fireblight is a serious plant disease present in the UK and most of mainland Europe, but has been considered absent from Guernsey.
This has recently changed as infection has been confirmed on apple and hawthorn trees in St Peter's, and on hawthorn trees in the Forest.
From the outbreaks confirmed so far it is considered highly likely that infection will be present elsewhere and gardeners and landowners are being asked to check their trees and report any symptoms.
Typical symptoms include the blackening of flower clusters, and the withering of young shoots which can take on a scorched appearance.
In severe cases whole branches and entire trees can become infected.
From the outbreaks found to date it is thought likely that infection will be limited to young shoots which seem to be highly susceptible.
Other plants that can become infected include, Firethorn (Pyracantha), Cotoneaster, Juneberry (Amelanchier), Mountain Ash (Sorbus), Quince (Chaenomoles & Cydonia) and Medlar.
Plant health inspector Nigel Clark said the presence of Fireblight is a threat to apple orchards, hawthorn hedgerows and a range of garden plants.
'If your apple, pear or hawthorn trees have suddenly taken on a scorched appearance then they may have been infected with the bacterial disease Fireblight.
'It will be important to identify any outbreak sites to assess whether there is a chance that this disease can be eradicated locally.'
Anyone who thinks they have found an infected plant can take samples of the infected flowers and shoots to the States Analystical Laboratory in Longue Rue, St Martin's [GY4 6LD].
Samples should include the transition between the dead and healthy parts of the plant, as this is where the disease will be most active.
Alternatively, symptoms can be reported to the Plant Health Inspector at email@example.com or a phone message can be left on 711161.
For more information on the disease visit https://www.gov.gg/fireblight.