Bacteria

Bacteria are microscopic single-celled organisms that occupy a vast range of habitats. Many bacterial species are crucial for ecological processes such as decomposition and nutrient cycling. Many also cause diseases in humans, other animals, and plants. Some of the most damaging diseases to agriculture are caused by bacteria. Despite the broad diversity and large number of pathogenic bacteria, only relatively small numbers are known to commonly cause diseases in Canadian trees. There are five bacterial tree diseases in this database, caused by bacteria in three different taxonomic orders.

Order Enterobacteriales

Family Enterobacteriaceae

This family of species consists of Gram-negative bacteria that are rod-shaped and usually measure 1–5 micrometres in length. Some species in this family are dangerous human pathogens, such as Salmonella and Escherichia coli.

• Fire blight
  Pathogen name: Erwinia amylovora (Burrill) Winslow. et al.

Order Rhizobiales

Family Rhizobiaceae

This family of species consists of Gram-negative bacteria that are usually rod-shaped and aerobic. Some species are involved in nitrogen fixation and thus play an important ecological role by benefiting plant growth. Species in this family that cause plant disease do so by altering host development and inducing abnormal growths.

Order Xanthomonadales

Family Xanthomonadaceae

Two genera (Xanthomonas and Xylella) within this family cause economically important and serious plant diseases in agriculture. These aerobic bacteria are rod-shaped and Gram-negative.