Pseudomonas syringae (Bacterial Canker)

Pseudomonas syringae (Bacterial Canker) Within the most common cherry tree diseases we have the Gummosis, also known as Bacterial Canker.

The bacterium Pseudomonas syringae (Van Hall, 1904) infects the cherry tree and the bark exudes a resinous mixture of amber.

Various species of fruit trees are affected by the Gummosis  (cherry , almond, plum, peach o peach tree and apricot). It also affects citrus such as lemon or orange.

Causes of cherry gummies

The bacterium Pseudomonas syringae penetrates the trunk of the cherry tree through the cracks in the bark

The zones with significant thermal gradient, very cold or vega are more affected by the gummies. This is due to the fact that when water droplets freeze in the trunks, the vegetal tissues that contain it grow. This produces that when it thaws when the tissues recover their original shape the water droplets are sucked dragging bacteria to sensitive areas of the trunk.

Gummosis: Treatment and Control

Cultural measures

Avoid pruning in autumn, since open wounds can be infected by bacteria. Pruning during the winter and applying scar tissue is a good way to reduce infections.

Keep the cherry trees with a good nutritional status. Deficiencies in lime have been shown to favor bacterial infection.

Improve the water status of the cherry tree, if we have the possibility to perform regular irrigation risks during the summer.

Elimination of serpents in autumn (they are potential carriers of the bacteria).

Chemical treatments against Gummosis

It is not easy to control the bacterial canker once it occurs, but we can use different measures of preventive control.

There are no chemical treatments that directly cure the gummies, this is produced by bacteria and the application of antibiotics on plants and trees is prohibited in the European Union.

However, we can control the gummies with organic treatments based on cupric compounds.

The autumn and spring treatments with copper on the trunks, reduce the bacterial load and limit the incidence of bacterial cancer. Being an ecological treatment quite effective against gummosis.

Even so, it is advisable, especially in plantations less than 6 years paint the trunks with copper.

Authorized treatments for cherry gum disease 2017 Amount for a backpack:

1kg of Copper oxychloride or in another form used for fungicide treatments

2kg of white plastic paint for outdoor

14 liters of water

Also the application of certain fungicides helps to control the populations of Pseudomonas syringae. Therefore, the following active matters are authorized on November 4, 2017.
Captan 47.5%, Captan 80%, Folpet 50%, Folpet 80%, Mancozeb 17.5% + Copper Oxychloride 22%, Mancozeb 20% + Copper Oxychloride 30%, Mancozeb 8% + Cuprocalcium Sulfate 20%, Cuprous Oxide 40%, Tiram 50% and Tiram 80%

Cherry Gummies

In cherry, varieties such as Rainair and Napoleon are especially sensitive to bacterial canker or gummosis.


A significant part of the information, comes from Spanish research organizations. When phytosanitary products are used, it is important to verify that their use is currently authorized in the country of application.

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