Russian Olive Decline and Gummosis

Compiled by Ned Tisserat, Colorado State University:

Taxonomy

Domain	Bacteria
Phylum	Proteobacteria
Class	Gammaproteobacteria
Order	Pseudomonadales
Family	Pseudomonadaceae
Genus	Pseudomonas

Scientific Name

Pseudomonas syringae

Scientific Name Synonyms

Phytomonas syringae

Common Name

bacterial leaf speck

Hosts

Russian olive (Elaeagnus angustifolia)

Diagnosis and Damage

Gummosis is a description of a symptom. Symptoms of gummosis include exuding of amber color gum from the trunk or branches of a tree that hardens with time. The tree will usually have other symptoms, including death of one or more branches and yellow leaves. Death of the entire tree may take one to seven years. The exact cause of gummosis in Russian Olive is currently not known, but appears to be stress related.

Biology and Disease Cycle

The causes of gummosis on Russian olive are unknown. It is believed that stress is a component, and that gummosis is an indication of root dysfunction. This root related stress may come from many sources including disease or adverse environmental conditions such as drought and sometimes signs of canker diseases can be found in trees exuding gum, but this is not always the case.

Conditions Favoring and Management of Disease

Conditions that stress the tree, environmental stresses such as too much or not enough water, extreme temperature fluctuations, or other stresses such as heavy pruning, or wounding will favor disease development. Management options include attempts to increase vigor of susceptible trees and decrease stresses to the tree.

Related Information

Honeylocust and stone fruit species also exhibit gummosis, but in these trees the cause of the gummosis is known.

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