Olive Bacterial Canker

Class: Bacteria

Common Name

Olive bacterial canker, Olive knot, and Olive tree tuberculosis

Scientific name

Pseudomonas savastanoi

Potential Hosts


Who am I?

A disease caused by the bacteria Pseudomonas syringae and is characterized by the formation of rough woody-like galls on branches and trunks that are approximately 1 inch thick. Defoliation and reduced yield in mature trees occurs, and young infect trees might die. The bacteria penetrates through cracks and openings in the plant's tissues provided by freezing injuries (or pruning) and is easily spread by water splashes. The infections will likely occur during wintertime, while the development of knots will take place later on such as spring or summer. All varieties are susceptible.

Control measures


Sanitation: Remove knots using sterile pruning tools. Reducing the presence of knots helps to diminish the overall spread of the bacteria.

Oleander plants can act as a reservoir; therefore, removing oleander plants growing next to olive trees can prevent the initial infection.

Conventional (chemical)

Control requires preventive application treatments with copper oxychloride or copper hydroxide in order to reduce the bacteria population found on the plant surface.

Caution and careful notice should be taken when using any plant protection products (insecticides, fungicides, and herbicides). It is the grower’s sole responsibility to keep track of the legal uses and permissions with respect to the laws in their country and destination markets. Always read the instructions written on labels, and in a case of contradiction, work in accordance to the product label. Keep in mind that information written on the label usually applies to local markets. Pest control products intended for organic farming are generally considered to be less effective in comparison to conventional products. When dealing with organic, biologic, and to some extent a small number of conventional chemical products, a complete eradication of a pest or disease will often require several iterations of a specific treatment or combination of treatments.

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