Assessment of rot incidence during fruit grading will give an indication of the problem in the orchard and the risk of rotting in store due to brown rot can be assessed pre-harvest to decide on storage potential.
- In late August or as near harvest as possible, inspect 20 trees at random in the orchard and record the numbers of fruit infected with brown rot. Include dropped fruit as well.
- Record total fruit on about five trees to give an estimate of numbers of fruit per tree.
- Estimate % fruit with brown rot/tree.
- Numbers >1% brown rot indicate a significant risk of brown rot in store.
- Orchards with early varieties such as Discovery or Grenadier as pollinators, which have a high incidence of brown rot, will increase the risk of brown rot.
- No forecasting methods have been developed for brown rot of apple.