Fruit rots
Symptoms caused by the three fungal species on fruit are similar and symptoms are similar on all cultivars.
- The fungus usually enters via a lenticel producing a cheek rot, but it may also occur around the stalk or calyx where it enters via a wound or small crack.
- The rot is mid-brown (possibly darker on Egremont Russet), circular, moderately firm and frequently, but not always, forms concentric zones of different colours as the tissue is invaded.
- Lesions usually have yellow centres on Cox, progressing to dark brown at the interface between healthy and infected tissue.
- On Egremont Russet the rots are often uniform brown.
- Cream-coloured slimy pustules may be produced during storage on rots caused by Gloeosporium spp.
- Pink/orange slimy pustules may be present on rots caused by Colletotrichum spp., particularly after they have been in the rot bin for a day or two.
- The rot is rarely seen in the orchard.
Cankers
Cankers caused by Gloeosporium spp. (perennial canker) resemble those caused by Nectria galligena.
- They are elliptical, sunken and, in older cankers, the bark sloughs off.
- Black pinhead-sized fruiting bodies (acervuli) may be present which ooze opaque slimy spore masses in wet weather in the summer.