Advice
Brown rot
Plants affected
This disease affects apples, pears, plums and most other cultivated tree fruit.
Symptoms
The first symptom is a small brown spot that enlarges to cover the whole fruit. Then concentric rings of pale grey or buff-coloured pustules appear (see left) - these are the spores of the fungus that spread the disease. The affected fruits either fall or remain on the tree in a mummified state (see below). The fungus may spread into the spurs from affected fruit, causing dieback. Fruits in storage may also be affected.
Cause
A
fungal disease that enters fruit mainly through wounds. Insect
damage (especially codling moths and wasps), bruising during
harvesting and damage from apple scab are all responsible for allowing
the disease entry. It is spread by spores (the buff pustules)
that are carried on the wind, on insects or by physical contact
between fruits.
Prevention and non-chemical control
- Remove all damaged fruit.
- Prune out and dispose of (but not on the compost heap) dead shoots or spurs and any mummified fruits that remain on the tree, as the disease can overwinter on these.
Chemical control
None is available for brown rot itself. However, controlling the pests and diseases (e.g. codling moth, apple scab) that allow the fungus to colonise the fruit may reduce the incidence of brown rot.
Plum cultivars such as 'Czar', 'Jefferson', 'Ontario' and 'President' show some resistance to the disease.