Mucor rot can occasionally be seen on fallen fruit on the orchard floor prior to harvest, but is more common in the orchard on fallen fruits in the 1-2 months after harvest. It is also common as a store rot.
- Mucor invades fruit through wounds or cracks anywhere on the fruit surface causing a pale to mid-brown, very soft wet rot.
- Rapid softening of the tissues occurs leading to a slimey disintegration of the flesh.
- Although the skin remains present it is very weak and collapses under the slightest pressure.
- On Bramley, and other open calyx varieties, it can also invade through the open calyx entering during the drenching operation.
- The apple tissue then rots internally leaving the peel parchment-like and intact and forming a fragile sack of almost liquid flesh.
- The Mucor fungus cannot penetrate the peel but emerges through any damaged area to produce a profuse growth of white coarse mycelium bearing black pin-shaped spore heads.
- Mucor rot can spread by contact but more usual are individual soft rotted fruits.