Biological control (Apple canker)

Research has indicated that biological control of leaf scar infection is at least feasible. The tissues of leaf scars become invaded by various host-specific fungi, common primary saprophytes and bacteria.

  • A strain of the naturally occurring fungal organism Trichoderma atroviride is commercially available to UK apple growers as an EAMU authorisation (Vintec 1890/24). It is applied as a spray to dormant trees (crop stage BBCH 97) once all leaves have fallen. It competes with pathogens for space and nutrients, creating an inhospitable environment for pathogens on the plant surface, and is recommended for controlling Neonectria ditissima. Application should be made at temperatures above 10oC and humidity greater than 70%.
  • Experimentally an isolate of Bacillus subtilis was found to be highly antagonistic to N. ditissima when applied to leaf scars immediately after leaf removal.
  • Other potential antagonistic fungi included Alternaria spp. and Trichoderma viride.
  • Research in AHDB Project TF 223 (Improving integrated pest and disease management in tree fruit) assessed the use of soil amendments with biological control agents. Amending soils with Trianum G (Trichoderma harzianum) in newly planted orchards and stoolbeds, showed some promise in reducing the incidence of canker development. This is not currently approved for use in apple orchards and would require the product to be registered for this use before growers can legally use it in this way.
  • So far no biocontrol agents for Neonectria have been developed commercially.