Brown rot
Fruit turning brown and soft with concentric rings of buff pustules, often while still hanging. Affected fruit shrivels into a hard 'mummy' that stays on the tree over winter and infects next year's crop from where it hangs.
Caused by: Monilinia fructigena and Monilinia laxa
Described view
Three apples on one surface with a scale reference: one split cleanly along a fresh crack with pale unblemished flesh showing, one carrying the corky olive-brown scab lesions that crack the skin as the fruit expands, and one with the concentric buff pustule rings of brown rot spreading from a wound
What brings it on
The fungus enters through damaged skin, so anything that breaks the surface — codling moth tunnels, bird pecks, wasp damage, splitting — opens the way. Warm humid weather and fruit touching in a crowded cluster spread it.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Brown rot
- Penn State Extension — Pennsylvania State University: Brown rot of stone fruit
Checked 2026-08-13
Usually seen: July, August, September, October
Preventing it
Ordered by how much difference each measure actually makes, not by how often it is repeated.
- Remove every mummified fruit from the tree in winter. This is the single most effective measure: the mummies are the overwintering source and they are easy to see on a bare tree.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Brown rot — control
Checked 2026-08-13
- Thin fruit so that individual fruits do not touch, and handle the crop gently at picking. Brown rot spreads between touching fruit and enters through bruises.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Thinning apples
Checked 2026-08-13
Dealing with it once it is there
- Pick off and dispose of infected fruit as soon as it is seen, and do not compost it in an open garden heap.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Brown rot
Checked 2026-08-13
What it affects
Signs that lead here
Each of these lists the other things that produce the same sign, and how to tell them apart.
On sprays and treatments
GrowingHQ does not tell anyone what to apply, at what rate, or how often. Pesticide approvals differ by country, change without notice, and the product label is legally binding — it is also the document you are holding. What is described here is cultural and physical control, which is what a home grower can act on without a label in front of them.
Plant-specific guides
Where this is one of several causes that look alike on a particular plant, GrowingHQ publishes the differential rather than the general answer.