Losses in storage cabbage are caused by two main pathogens, Botrytis and Phytophthora. In the past growers had approvals for effective pre-storage drenches against both pathogens. A change in the MRL for metalaxyl-M, has effectively withdrawn this use due to a chance of MRL exceedance (please see notes below).
With this in mind, cultural and good harvesting practices are essential to help reduce losses from Phytophthora.
- Ensure crops are free of disease, leaf spots can be an entry point for rots and should be well controlled prior to harvest.
- Use an appropriate variety for longer storage and assess fields for their storability pre-harvest
- Harvest in dry conditions to minimise soil contamination of head (especially cut surfaces), this will reduce Phytophthora contamination which is carried in soil.
- Keep knives clean and avoid cutting rotten or diseased heads
- Use clean boxes
- Ensure tractor wheels don’t splash soil onto harvested heads
- Load boxes from a clean area to ensure soil is not placed on the top of harvested boxes during stacking
- Take care during transport to the store to ensure harvested boxes are not contaminated by road spray etc.
- Move boxes quickly to store, load complete stores and reduce the number of times stores are opened for long term storage.
Notes – SL567A MAPP No. 12380 has an EAMU approval for use as a storage drench, but this is not supported due to the chance of MRL exceedance. MAPP No. 12380 has a last use/expiry date 31/12/2024.