Divisi
Armillaria root rot
Armillaria spp. · Fungal
Photo: Antrodia · CC BY-SA 3.0
Armillaria root rot (also called honey fungus) is a soil fungus that lives for years in buried stumps, dead roots and woody debris. It travels from dead wood to living plants along black, bootlace-like strands, then grows in a white sheet under the bark at the base of the trunk and rings the root collar — cutting off the plant's food and water until it dies. It kills perennial tree crops such as coffee, tea, banana, avocado, citrus and mango in slowly expanding patches.
Craig L. Schmitt, Michael L. Tatum (US Forest Service) · Public domain 
Rosser1954 · CC BY-SA 4.0
Why it matters
Armillaria root rot is a killer, not just a spoiler. Once it rings the base of a tree it cuts off all the food and water going up and down, so you lose the whole tree — up to 100%, not just one season's fruit. Worse, it spreads underground from tree to tree along black, root-like strands, so one sick tree quietly infects its neighbours down the row. And it is very hard to stop once it takes hold, because the fungus hides deep in the roots and dead wood where no spray can reach it — the only cure is to dig the infected tree out and burn it. Catching the very first declining tree early is what saves the rest of your orchard.
When to act
Investigate as soon as isolated trees wilt or decline; act on the first confirmed tree to stop spread to neighbours.
This guidance is general, compiled from published agronomic references including FAO and CABI. Thresholds and timing shift with your crop, your variety and the season.
In much of the region a spray is simply called mushonga — medicine. But a chemical group you cannot name is one you cannot rotate, and a product you did not write down has no pre-harvest interval you can observe. Mushonga, and other farming words →
The full armillaria root rot field guide
- Identify it
- Scout for it
- Control it
18 field-guide sections in the app
The full guide to armillaria root rot — every symptom to check, how and when to walk your field looking for it, and the controls that actually work, ranked. Built into your crop plan, so you are told to look before it costs you a harvest.
Crops it affects
Frequently asked questions
How do I identify armillaria root rot?
First sign — one tree looks sick while its neighbours stay healthy. Its leaves turn pale and yellow, the canopy thins out, new growth is stunted and small, and branches begin dying back from the tips. Some trees fade slowly over a season or two; others suddenly wilt and collapse in a dry spell with the dull, dead leaves still hanging on. Because the fungus travels root-to-root, the dying trees form a patch or gap that creeps down the row — that spreading patch is the biggest giveaway.
When should I take action against armillaria root rot?
Investigate as soon as isolated trees wilt or decline; act on the first confirmed tree to stop spread to neighbours.
How do I control armillaria root rot?
Prevent it (your strongest defence) — clear old wood before you plant. Dig out and burn old stumps, big dead roots and buried wood before you establish an orchard. That rotting wood is the fungus's food store; leave it in the ground and you feed the disease for years. This single step does more than anything else you can do.
Which crops does armillaria root rot affect?
Among the crops covered here: Avocado, Mango, Tea.
Catch it before it costs you a harvest
Divisi builds scouting into your crop plan — it tells you when to walk your field, what to look for at that stage, and what to do when you find it. Free for farmers, works offline.
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