Brown rot

Monilinia laxa and Monilinia fructigena

Fruit rots brown on the tree with buff rings of spores, then mummifies. Remove all affected and mummified fruit promptly, on and under the tree.

Fungus Serious Spread by contactAirborne sporesSpread by insects Spreads to neighbors

What you'll see

A soft brown patch spreads from a wound or bruise until it takes the whole fruit.
Buff or cream cushions of spores form on the brown flesh, arranged in neat concentric rings.
Rotted fruit shrivels to a hard, wrinkled black mummy and hangs on the branch through winter.
Fruits touching in a cluster pass it along, so the rot runs down a whole truss.
On plums and cherries the blossom and spur may also wither and die back, with a gummy ooze at the base.

Why it happens

A fungus that overwinters in mummified fruit and in infected spurs and small cankers, releasing spores at blossom time and again as fruit ripens. It cannot break intact skin, so it needs an entry point: a bird peck, wasp damage, a scab lesion, a split from heavy rain, or a bruise from handling. Fruit touching an infected neighbor is infected by direct contact.

Warm, wet weather as fruit ripens is ideal, especially in a congested, unpruned crown that stays damp. Heavy unthinned crops with fruit pressed together suffer the worst.

Treating it

Pick off every rotted fruit as soon as you see it, handling it gently so the spores are not shaken over the tree.
Search out and remove the hard black mummies on the branches in winter, and clear all fallen fruit from beneath.
Bin or burn affected fruit rather than composting it or leaving it in a heap at the end of the garden.
Cut back any withered, gummy spurs and blossom trusses to clean wood.
Control wasps, birds and scab, which make the wounds it needs to get in.

Keeping it away

Thin the crop in early summer so no two fruits touch on the spur.
Prune to an open crown so air and light reach the fruit and it dries quickly after rain.
Handle fruit carefully at picking, and store only sound, unbruised fruit in a cool airy place.
Clear all windfalls weekly through the season rather than at the end of it.
Keep on top of scab and codling moth, whose damage opens the door.

Who gets it

Apples, pears, plums, cherries, peaches, apricots and quinces, along with ornamental prunus and cotoneaster.