What is Armillaria?

Armillaria mellea, also known as honey fungus or Bootlace fungus, causes Armillaria root rot on many types of trees. It is a serious problem because there is no cure.

How does Armillaria damage fruit trees?

The honey-coloured mushrooms can be seen at the base of infected trees, but the major part of the fungus is underground. Its mycelial threads can extend for great distances and spread from one tree to another. The mycelial threads become larger rhizomorphs which enter the tree roots and grow up the cambium, blocking the nutrient channels, causing reduced growth, rot and the death of the tree. The fungus may also colonize a healthy tree by means of its spores which can germinate on the bark and enter the nutrient channels through a wound.

Armillaria mellea Honey Fungus
By Stu’s Images, CC BY-SA 3.0

How to treat Armillaria root rot

If you notice the appearance of honey fungus on one of your trees, unfortunately the only solution is to immediately cut down the tree and remove the stump and as much as possible of its roots.

Go back to the pests and diseases page.