Why Are My Apricots Rotting on the Tree?

Brown rot caused by the fungus Monilinia laxa is the most destructive disease of apricots in UK gardens. It can turn a promising harvest into a total loss within days — ripe or near-ripe fruit develops a brown spreading lesion, white or cream pustules of fungal spores appear on the surface, and the fruit collapses and shrivels. The disease spreads rapidly from fruit to fruit and also infects blossoms and young shoots, making control a year-round management task rather than a single intervention.

Identifying brown rot

Brown rot starts as a small brown spot on the fruit surface — often at a wound site, crack, or insect entry point — and spreads rapidly to cover the entire fruit. Within a day or two of visible infection, cream-coloured pustules of fungal spores appear in rings or irregular clusters on the surface. The fruit turns dark brown, softens, and eventually shrivels into a hard, dark mummy that persists on the tree through winter. These mummies are the primary source of infection for the following season.

Sanitation: the most important control

Remove all infected and mummified fruits from the tree and from the ground below it as soon as they are identified. Do not compost mummified fruit — bag and bin it or burn it. In winter (November to February), walk the tree systematically and remove every remaining mummy. These persist on the spurs and short laterals and release spores at blossom time, infecting flowers and the base of young shoots. Removing them dramatically reduces the disease load the following season.

Reducing spread during the season

Brown rot spreads most rapidly when fruits are touching — the spores transfer directly through point of contact. Thinning fruits so they do not touch one another (10–15 cm minimum spacing) significantly reduces fruit-to-fruit spread. Keep the canopy as open as possible through summer pruning to improve air circulation. Harvest fruit before it is fully ripe if brown rot is active — slightly underripe fruit is far less susceptible than fully ripe fruit.

Fungicide options

Organic-approved copper-based fungicides applied at blossom time reduce blossom infection. Conventional fungicides containing myclobutanil or tebuconazole can be applied at blossom and again when fruit is close to harvest if brown rot has been severe in previous seasons. Always follow label instructions and observe pre-harvest intervals.