Page 39 - Green knowledge 2024

Photo: Dag-Ragnar Blystad
Phytoplasmas cause major problems
Phytoplasmas are tiny bacteria that cause growth disorders in plants and crop loss. Since
no measures exist to eliminate phytoplasmas from infected plants, it is crucial to prevent
their spread.
Phytoplasmas are small bacteria that lack a cell wall.
They cause growth abnormalities in host plants,
potentially resulting in crop loss. Examples include
witches’ broom in apples, stunting in raspberries,
and pear decline.
“We know of more than 100 phytoplasma species,
and six phytoplasma diseases have been identified in
Norway. The most well-known ones are found in
raspberries, apples, and pears,” says NIBIO
researcher Dr Özgün Candan Onarman Umu.
In winter, phytoplasmas can survive in the roots of
perennial plants and spread via the phloem in
spring. Symptoms vary by phytoplasma type and
plant species and include thin lateral shoots, abnor-
mal leaf growth on flowers or fruit, and premature
bud burst.
“Some of these symptoms may be due to natural
mutations. If infection is suspected, lab testing is
vital to detect phytoplasma DNA.”
The most important measure to prevent spread is
using healthy plant material. Phytoplasmas cannot
move between plants on their own but are often
spread when humans unknowingly use infected
material for planting or grafting. They are also
spread by sap-sucking insects.
“To prevent spread, producers must test mother
plants for infection and keep them free from insect
vectors,” says NIBIO researcher Dr Dag-Ragnar Bly-
stad.
If a phytoplasma is detected, all symptomatic plants,
including roots, should be destroyed. Witches’
broom and pear decline are quarantine pests in
Norway, and any findings must be reported to the
Norwegian Food Safety Authority.
Purpose: Funding: Contact: The purpose of OBO Phytoplasma is to strengthen NIBIO’s phytoplasma research community by
broadening knowledge of phytoplasma diseases worldwide and developing specialised expertise on
the situation in Norway.
The Research Council of Norway
Research Scientist Özgün Candan Onarman Umu, Division of Biotechnology and Plant Health.
Email: ozgun.umu@nibio.no | Phone: +47 939 71 640
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