Armillaria spp.: attack of the deadly bootlaces!

Even as the days become shorter, there’s always time to admire other forms of biodiversity out there on campus. Take these fungi, for example…

I found these last month by Creighton Court (off Northcourt Avenue). I think it could be one or several species of honey fungus (Armillaria spp.), here growing saprobically on a tree stump. There are seven species of Armillaria in the UK, the most common species in gardens being A. mellea and A. gallica.

To check whether a plant is infected with honey fungus, peel away the bark at the base, as shown here with a Fraxinus sp. root. (Photo: Down Garden Services)

Armillaria is a genus of fungi that attack and kill the roots of many woody and perennial plants. In fact, it is the most destructive fungal disease in UK gardens! One characteristic symptom of honey fungus is a thin, white-ish layer of fungal tissue (mycelium hyphae) between the bark and wood, usually at ground level.

The fungus spreads underground by direct contact between the roots of infected and healthy plants. In addition, black, root-like structures called rhizomorphs (often known as “bootlaces“), can spread from infected roots through soil. An ability to proliferate over long distances makes honey fungus a very destructive pathogen, often attacking plants up to 30m (100ft) away from the source of infection!


This year has been (and indeed continues to be!) particularly good for fungi – so happy hunting!

About Waheed

Botanist at Reading University, twitcher and wildlife photographer...
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