Black rot and frogeye leaf spot: how to recognise and treat it

Disease

Black rot and frogeye leaf spot — Photo: Clemson University, CC BY 3.0 us, Wikimedia Commons

Symptoms

Small purple leaf spots grow into round "frogeye" spots with a purple rim and a brown or tan centre.
Fruit rots from the blossom end, usually one spot per fruit, with alternating brown and black rings.
Rotted fruit dries into a shrivelled black mummy.
Sunken reddish-brown cankers on limbs, where the bark later loosens and peels off.

Organic treatment

Prune out cankers, dead branches and twigs.
Remove all mummified fruit from the tree and the ground.
Cut out fire blight strikes promptly, because the fungus enters through them.

Chemical treatment

Fungicide with captan applied early and regularly through the season; follow the label dose and pre-harvest interval.

Reference information, not a guarantee. Read and follow the label of any product: dose, safety and the days to wait before harvest.

Prevention

Keep the tree free of dead wood, which carries the fungus.
Do not leave prunings and rotted fruit near the trees.
Control fire blight, which opens the way for this disease.

Plants it affects

Sources

Figures checked against these sources.