Pacific Pests, Pathogens & Weeds - Mini Fact Sheet Edition

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Citrus butt & root rot (004)

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Photo 1. Ganoderma sp. growing from the base of an orange tree, which is still alive. Note the dark upper surface with the distinctive white margin.

Photo 2. Another Ganoderma species. The young backets can be seen on the left of the trunk. In this case the tree is dead.

Photo 3. Underside of Photo 1, showing the light grey colour of this active spore producing-bracket.

Photo 4. Tremetes on a dead citrus trunk showing stacks of brackets, one on top of the other.

Summary

• Worldwide distribution. The fungi that cause these diseases (commonly, Ganoderma and Trametes) have a very wide host range, including many forest, fruit and plantation trees, including palms. Important diseases.
• The fungi cause white rots in roots and trunks, causing slow dieback and death. The brackets that develop remain for many years, producing millions of spores.
• Spread is either root-to-root or spores infect through wounds. Spores travel long distances on the wind.
• Cultural control: make regular checks for brackets and, if found, dig out infected trees, with the main roots, and burn; seek the source of infection, e.g., old stump of forest tree; plant ground legumes to hasten decay of stumps; do not damage healthy trees: stop people cutting the bark with bush knives!
• Chemical control: none recommended.

Common Name

Butt and root rot

Scientific Name

Ganoderma and Trametes. There are many species of both, and not all are plant pathogens, especially those belonging to Trametes. Also, see Casuarina butt rot caused by Ganoderma applanatum (Fact Sheet no. 195).

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