At a Glance
- Cherry powdery mildew is a fungal disease affecting leaves and fruit.
- Infections appear as white powdery growth, often in circular patches.
- Infected fruit can contaminate entire boxes during packing and storage.
- The disease overwinters on leaf tissue and tree structures.
- Washing does not remove the infection, and mildew can re‑establish in storage.
- The BC DAS system helps track risk and plan protection timing.
Why Is Cherry Powdery Mildew a Problem?
Cherry powdery mildew is a surface fungus that develops on both leaves and fruit. It appears as white fungal growth, often forming circular patches on affected surfaces. The presence of powdery mildew damages fruit quality and can lead to rapid contamination during harvest and packing. Infected fruit may begin to deteriorate and spread the disease to neighbouring fruit within bins or boxes.
Where Does Cherry Powdery Mildew Come From?
Cherry powdery mildew overwinters as ascospores on leaf tissue or within crotches of tree limbs. Under favourable conditions, spores are released and settle on new, developing tissue.
Powdery mildew can be difficult to detect during packing because washing and cooling may remove the visible surface layer. However, this does not eliminate the infection. Once packaged, mildew can re‑establish and spread within fruit boxes during storage.
How the BC DAS System Helps
The BC DAS system provides growers with information on current cherry powdery mildew risk based on their orchard location. Using temperature data and wetness events, the system identifies periods when infection risk is elevated and when protection measures may be needed. For best results, growers should combine model outputs with observations from their own orchard to stay informed throughout the growing season.
The DAS Spray Guide provides spray options, rates, and timing recommendations to support powdery mildew management. The guide allows growers to select products registered for conventional or organic use and plan spray programs accordingly. By following the BC DAS model and Spray Guide together, growers have access to timely information and tools to help protect fruit quality from powdery mildew.