Instructions for sampling:

It is only possible to isolate the bacteria (Erwinia amylovora) from fresh, active lesions, where healthy tissue meets the diseased tissue - the lesion margin.

It is impossible to isolate fire blight bacteria from dead, dried out tissue.

The Lesion Margin
Collect samples that include about 3 inches of healthy tissue beyond the infected tissue, and include about 3 inches of infected tissue. Do not submit all the dead branch of the strike, this is often too long and can be cut back, as described, to 3 inches of infected tissue above 3 inches of healthy tissue.

If possible, refrigerate infected trees and strikes.
Protect samples from drying out prior to submitting them.

Do not collect entire branches or trees unless symptoms are unusual.

Please see the attached form for more information.

Fire Blight Sample Form (pdf; 226KB)