Fragrant pest control in forest nurseries

Every year, 40 million spruce trees are planted in Norway. In forest nurseries, young plants grow densely before being transplanted, making it easy for diseases to spread. The fungal disease grey mould is particularly challenging. Chemical fungicides are used to combat the disease, but their use poses risks to both human health and the environment. Additionally, grey mould easily develops resistance to these treatments.

Researchers at NIBIO are currently investigating ways to reduce pesticide use by enabling plants to defend themselves against disease.

"When a spruce tree is under attack, it releases methyl jasmonate, a chemical that smells like jasmine flowers," explains NIBIO researcher Dr Melissa Magerøy. "This substance acts as a warning signal to other trees, alerting them to prepare their defences. If a tree detects methyl jasmonate, it can activate its defence system pre-emptively. This makes the tree more resistant to diseases and pests," she adds.

Dr Magerøy leads a project to treat spruce seeds and young plants with methyl jasmonate and "friendly" bacteria to enhance their resilience. The friendly bacteria naturally live in the soil around spruces. They can either directly inhibit pathogens or release substances that stimulate the spruce tree’s own immune response.

In this project, researchers are working closely with industry partners to tackle practical, real-world issues. They believe the combination of methyl jasmonate and friendly bacteria will be effective in combating grey mould.