Defoliation, drooping and yellowing of noni leaves associated
with stem blight disease. |
Yellowing and drooping of noni leaves associated with stem blight
disease.
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Rotten roots and blackened basal stem associated with stem blight
disease. A white tuft of fungal mycelium (the fungus, Sclerotium
rolfsii) forms just above the soil line. |
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Disease: Noni
stem blight.
Pathogen: Pathogens associated
with this disease are a fungus Sclerotium rolfsii, and
root-knot nematodes. Apparently, the disease occurs when plants
are greatly stressed from nematode attack and/or flooding.
Symptoms: Foliar chlorosis and wilting; stem girdling
at or near soil line; internal stem necrosis; stem rot; defoliation;
plant death.
Signs: White fluffy fungal mycelium;
brown sclerotia at soil line.
Disease distribution:
The fungus associated with noni stem blight has a world wide
distribution, although the disease has only been observed in
the Puna district on the island of Hawaii.
Epidemiology:
Noni stem blight is an opportunistic disease favored by predisposing
stresses (flooding, poor drainage, wounding of stems, infection
by root knot nematodes).
Control: |
- Avoid planting in low-lying areas with poor drainage.
- Avoid plant-parasitic nematodes.
- Avoid injuring stems with weed-whackers.
- Do not pile rocks around the base of noni plants, as they
may injure the stem.
- Avoid undue plant stresses.
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| Notes:
Noni stem blight has not been reported previously to occur in
Hawaii or elsewhere in the world. |
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