Grey mould has appeared on bark of my lilac tree

Q: A grey mould has appeared on the bark of my white lilac tree at ground level. Can you tell me what it is and whether it can be treated? Should I get someone to dig it out?


A: The bark sample you sent was perfectly healthy, with nothing more on its surface than lichens and algae. These are harmless and need not be treated.
Pale, grey-green growths like these can often be mistaken for fungal infections and that can cause concern. After two moist summers, lichens have been more widespread than usual, particularly on the trunks and branches of mature shrubs. But their presence makes no difference to plant health.
Serious diseases such as honey fungus or phytophthera are usually first spotted when plants begin to die. The white fungal sheet with honey fungus grows beneath the bark as rule, rather than on the surface. So if your lilac looks healthy and has plump buds for next year, there’s no need to worry.