Fire Blight Erwinia amylovora

Diana Pimentel
InnovPlantProtect
10 November 2021

Abstract
Erwinia amylovora (Burrill) Winslow et al. is the causal agent of fire blight in approximately 200
species of the Rosaceae family. Fire blight is one of the most devastating diseases of pear and apple.
The most common symptoms of fire blight are the blackening and wilting of blossoms and fresh
shoots, which reflects the main areas of entrance and proliferation of the pathogen, and the necrosisand withering of organs or entire sections of the affected plants caused by the proliferation of thepathogen in the host tissues and vascular system. E. amylovora is a protected zone quarantine pest.
Since Portugal is no longer a protected zone, this pathogen is considered a regulated non-quarantine pest (RNQP). E. amylovora is widely distributed across North and Central America and Europe, and is present in the Middle East and southern Mediterranean area. Temperature and humidity are critical factors for the development of fire blight, being temperatures from 18 to 29°C and high relative humidity (90–95%) the most favourable conditions. E. amylovora can be spread by insects, rain, wind, infected propagation material and non-disinfected pruning tools. Some predictive models have been developed, such as Maryblyt and Cougarblight, based on risk factors like temperature and humidity. Fire blight can be detected through visual inspection in the field and confirmed through laboratory tests. Available control methods in Portugal include chemical treatments (copper, fosetyl-Al, acibenzolar-S-methyl, laminarin and prohexadione-calcium) and biological control agents (Bacillus amyloliquefaciens QST 713 and Bacillus amyloliquefaciens subsp. plantarum, strain D747). Sanitation of pruning tools, removal of overwintering cankers, grafting on resistant rootstock and reduce nutrient application are cultural practices important to prevent fire blight infection.