apricot brown rot (fructigena)

Symptoms

Soft brown rot of ripening fruit, buff-coloured spore tufts in concentric rings, mummies stuck to twigs through winter, rapid spread on touching fruit in dense clusters.

Plants affected

• apricot
• quince
• medlar

Easily confused with

• quince black knot canker

  How to tell them apart: Monilinia fructigena: look on the fruit for an expanding soft brown rot bearing raised buff-to-tan cushions (sporodochia) arranged in concentric rings on the rotted surface; mummified fruit stays on the twig and infection moves into the spur causing blossom and twig blight. Diaporthe perniciosa: look on twigs and small branches for sunken, sharply margined bark cankers and progressive dieback, with the dead bark studded by tiny black pimple-like fruiting bodies (pycnidia) often oozing pale tendrils in wet weather; any fruit lesion is firmer, darker and lacks the orderly concentric buff rings.

• codling moth

  How to tell them apart: Cydia pomonella (codling moth) damage is a single, round entry/exit hole on the quince, usually near the calyx (eye) or where two fruit touch, plugged or rimmed with reddish-brown crumbly frass (caterpillar droppings). Cut the fruit open and you find a curving tunnel boring toward the core, eaten seeds, and often a pinkish-white caterpillar with a dark head. The flesh around the tunnel is mainly intact, not soft. Monilinia fructigena (brown rot) is a spreading, soft, tan-to-chocolate-brown rotted patch covering much of the fruit, studded with concentric rings of small buff or cream cushions (spore tufts). There is no insect tunnel; the whole rotted area is soft and watery, and infected fruit often shrivel into a hard mummy that clings to the branch.

• fire blight

  How to tell them apart: Erwinia amylovora (fire blight) is a bacterium: infected quince blossoms and shoot tips suddenly wilt and turn dark brown to black as if scorched by fire, the shoot tip bending into a characteristic shepherd's-crook, and in warm humid weather milky-white to amber bacterial ooze beads up on the blackened tissue and the bark below the dead spur becomes sunken and water-soaked. Monilinia fructigena (brown rot) is a fungus: blighted blossoms and spurs turn tan to mid-brown (not the inky black of fire blight), there is no ooze and no shepherd's crook, and on the dead tissue, twig cankers and especially the rotting fruit it produces tufts of buff/grey-brown spore cushions (sporodochia) arranged in concentric rings. If you see blackened wilted blossoms with sticky ooze and a hooked shoot tip, treat it as suspected fire blight and report it to your national plant protection organisation (NPPO), as Erwinia amylovora is a regulated/notifiable organism in the EU.

• American brown rot of stone fruit

  How to tell them apart: Both fungi cause brown rot of apricot fruit with concentric rings of tan-to-buff cushion-like spore tufts (sporodochia) on the rotting surface, so the fruit symptom alone cannot tell them apart. Common Monilinia fructigena tends to produce buff to ochre-grey sporodochia, usually progresses more slowly, and is most damaging on ripe and wounded fruit late in the season; mummified fruit stay on the tree. The quarantine Monilinia fructicola is typically more aggressive: it causes rapid, expanding fruit rot, abundant fine grey-to-tan spore masses, and blossom blight with gummy cankers and dieback on flowering twigs, often early in the season. Because the visible signs overlap heavily, the two CANNOT be reliably separated in the field — laboratory confirmation (culture morphology or PCR) is required, and a suspected M. fructicola finding is a notifiable quarantine event.

• European brown rot / blossom blight

  How to tell them apart: M. fructigena is mainly a fruit-rot pathogen. The hallmark is a rapidly enlarging brown rot on ripening fruit covered with prominent buff-to-tan spore cushions arranged in conspicuous CONCENTRIC RINGS. Affected fruit shrivels into a hard, dark 'mummy' that often stays attached to the tree over winter. Blossom and twig blight are far less common than with M. laxa, and its spore tufts are warmer ochre/tan rather than mouse-grey. M. laxa is mainly a blossom and twig pathogen. Look for sudden wilting and browning of flowers and young shoot tips in spring, often with greyish (mouse-grey) tufts of spores on the dead blossoms. It causes elongated, sunken twig cankers, frequently with a gummy ooze, and the wilted blossoms and leaves cling to the shoot (a 'shepherd's-crook' dieback). On fruit the rot is firmer and brownish, with smaller, irregular grey-buff spore pustules that are NOT in neat rings.

Common questions

How do I recognise apricot brown rot (fructigena) on apricot?

Soft brown rot of ripening fruit, buff-coloured spore tufts in concentric rings, mummies stuck to twigs through winter, rapid spread on touching fruit in dense clusters.

Do I have to report apricot brown rot (fructigena)?

No. apricot brown rot (fructigena) is not a notifiable organism, so there is nothing to report to an authority. Treat it as a normal garden problem.

How is apricot brown rot (fructigena) treated?

Mainly with biological and cultural measures — removing affected material, changing the conditions that favour it, and treating with agents approved in your country. The exact steps and their timing depend on the plant, the season and where you live: Dr. Phyto works them out in a free diagnosis.