We thought we would use this post to focus on a relatively common plant pathogen - Kretzschmaria deusta or Brittle Cinder fungus, formerly known as Ustulina deusta.
This fungus has the potential to severely weaken trees by causing deep seated decay within the lower stem and roots.
It can be a difficult fungus to detect due to the size and location of the fruiting bodies. These tend to develop between the root buttresses at ground level forming initially as small, grey discs with a distinct white margin before maturing into black, tarmac like clumps.
We were recently commissioned to dismantle and remove a large 90 year old Lime on the outskirts of Newbury in Berkshire. The tree had been condemned by the local authority Tree Officer on the grounds of structural instability following the discovery of Kretzschmaria deusta around the base.
Although on the face of it the tree appeared healthy from the outside, the cross section of wood through the remaining stump told a different story; 90% of the wood was structurally unsound and significantly decayed.
The fungus forms grey then black tarmac like clumps, is easily overlooked or hidden by undergrowth and causes extensive decay in the stem base with little visual indication of the disease in tree vitality.