European Canker Best Management – Protecting Leaf Scars.
The recent rain events have created ideal conditions for EC. Soon tens of thousands of leaf scars will be created during leaf fall. It’s important you have a program to protect these wounds from infection. Do not underestimate the impact this disease can have on the economic viability of your orchard. Do not be complacent. It’s an aggressive disease which requires and equally aggressive response.
Best practice includes:
1. Canker walk your blocks NOW. Cut, remove and burn. Lowering the inoculum level in the orchard is the No.1 management tool. You can’t rely solely on spraying your way out of this disease.
2. Commence weekly Captan &/or Copper sprays between 10% and 90% leaf fall. At least 3-4 applications over the leaf fall period. Additional applications will be needed immediately following rainfall events.
3. The Copper & Captan a.i. rates are important for efficacy. Copper a.i. rate is 1.0 kg/ha, Captan a.i. rate is 2.0 kg/ha. Note: do not exceed 5.0 kg Cu/ha/year.
4. Check pH of spray solution. Captan needs buffering to <6.5 to ensure it does not hydrolyse (breakdown).
5. Adjust water rates to achieve complete coverage. Check/test sprayer set-up to ensure even spray deposition. This is crucial for maximum protection.
6. Consider assisted leaf drop sprays, e.g. EDTA Copper, in known high-risk blocks. You must wait until natural leaf has started (~5% leaf fall) before application. Shortening the period that scars from fallen leaves are susceptible to infection reduces the risk of European canker infection. Captan/Copper sprays to cover the wounds is still essential.
7. Do not apply foliar Nitrogen once leaf fall has started. This increases EC infection risk. If Urea is required for black spot clean-up, wait until all leaves have dropped and apply as a 5% solution to the ground.
Note: Sprays are supplemental to an aggressive cutting, removal and burning of inoculum from the orchard.
Dean Rainham, AgFirst Consultants
