OSCII Activity C.21

Development of organic control strategies for apple scab

Activity summary

The major challenge that faces organic apple production in most regions of the world, including Canada, is apple scab, a fungal disease caused by Venturia inaequalis that can result in a complete crop loss. Apple scab is the single major disease that affects organic apple production in most regions of Canada, and organic apple growers experience difficulty in controlling fungal disease during the summers. Significant losses were incurred due to scab in the organic apple industry in 2009. Efficacy of the available organic fungicides is lower compared to synthetic fungicides used in conventional apple production. Due to high levels of copper in orchard soils, the most effective fungicide component, copper, is banned in several Western-European countries, which calls for new alternatives against apple scab. Because of the extensive use of copper based fungicides in organic production, copper levels are increasing in soils in Canada. Very few disease control options are available for organic apple production in Canada and there is a need for the development of innovative and alternate control options for copper and sulphur. The control of apple scab has been identified as an important research priority by apple growers, extension specialists and service providers in Canada.

In this study, our main objective is to develop organic disease management strategies/program for apple scab to provide a commercially acceptable level of disease control with minimal pesticide use. Specific objectives of this study include:

  1. To identify fungicides, endophytic yeasts or fungal biological control agents and plant defense activators as alternatives to copper and to reduce sulphur inputs;
  2. To find the best combination of active substances and common organic fungicides for use in scab control strategies that minimizes the use of copper and phytotoxicity;
  3. To control primary scab inoculum by leaf shredding and the application of  endophyte biological control on fallen dead leaves with scab infection; and
  4. To conduct an economic analysis of an organic apple scab control program that will aid apple growers in financial decision making.

Our team proposes to develop pest management strategies, with a special focus on endophyte biocontrol and plant defence activators, for apple scab control in organic production and provide an economic analysis of the spray programs that include products with novel modes of action. The anticipated impact for the organic industry and organic value chain include the production of commercially acceptable levels of scab on apple fruit that will benefit organic farmers and processors by improving their cost effectiveness and profitability. Another benefit will be the reduction of pesticide (copper) inputs on the produce and in the soil environment.

Materials and Results to Date

Activity researchers

Name Affiliation
Deena Errampalli, Activity Leader Agriculture and Agri-Food Canada
Southern Crop Protection and Food Research Centre
Kerik Cox Cornell University
Paul Goodwin University of Guelph
John Molenhuis Ontario Ministry of Agriculture and Food