Fig. 27.—Canker fungus spreading down from a branch. 
This was photographed troma living specimen. The dark- 
coloured cortex near the branch is dead. The lighter 
coloured, above and below this, is alive. 
Fig. 28.—Spread of fungus down the branches. This 
stem was taken from a young tree which had been felled 
and allowed to lie in the wood for a few months. 
