Sustainable management of apple canker

New studies on site specific factors affecting apple canker and a novel method of disease management with endophytes

Title: Sustainable management of apple canker
Funder: Biotechnology and Biological Sciences Research Council
Industry partner: Worldwide Fruit; Avalon Fresh
Term: October 2023 to September 2025
Project leader: Xiangming Xu

Much effort has been spent in recent years seeking new approaches to apple canker which don’t rely solely on the use of conventional fungicides. NIAB has studied endophytes (bacteria and fungi which spend at least part of their life within a plant without causing apparent disease) and demonstrated the potential of the fungal genus Epicoccum for offering some control. A particular bacterial genus (Sphingomonas) is associated with scion cultivar tolerance against the canker pathogen. In addition, bacterial endophytes appear to be more persistent over growing seasons than their fungal equivalent.

The project

In this latest project, two strategies will be investigated. The first will study the impact of site-specific factors, including soil pH, organic matter and nutrient levels and type, on the development of canker symptoms from latent infection that occurred in the nursery. This could help growers to select sites with minimal risks to canker development during tree establishment in the orchard. The second will study Sphingomonas isolated from apple leaf scar tissue. It is a naturally occurring endophyte in apple, associated with plant health, and known to be capable of promoting plant growth. We will assess its seasonal dynamics following artificial augmentation across growing seasons to assess whether the level of its abundance is associated with tree health, and whether repeated application is necessary to maintain its abundance at a sufficiently high level to offer control.