Pests and Diseases 
Noni shot hole
Noticeable ?shot hole? appearance and yellowing of noni leaf
with shot hole disease. |
Tiny, pinpoint maroon-colored flecks on noni bracts. |
Tiny maroon-colored flecks and shot hole lesions scattered over
the surface of a diseased noni leaf. Chlorotic (yellow) halos
are visible around lesions. |
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Disease: Noni
shot hole
Pathogen: Noni shot hole is a leaf
spot disease that is associated with an unidentified fungus.
Symptoms: Initial spots are tiny, maroon-colored
specks on leaves and bracts. Specks develop into lesions (2-10
mm diameter) with bleached or tan centers and maroon margins,
often surrounded by or accompanied by yellowing of leaf tissue
around lesions. As the lesions mature the centers drop out,
leaving the typical “shot hole” appearance. Infected
leaves may abscise (drop) prematurely. Stems and fruits display
no symptoms.
Disease distribution: Noni shot
hole was first observed in the Puna district on the island of
Hawaii in 2001, and has since been observed in the Hilo/Panaewa
area. This disease is likely to become established wherever
noni is grown in areas that receive high or frequent rainfall.
Noni shot hole is common in noni plant nurseries, where plant
crowding is common and overhead irrigation is used.
Epidemiology: Noni shot hole is favored by warm, wet,
windy weather and high relative humidity. The fungal spores
are dispersed by wind and by splashing rain water.
Control: |
- Sanitation (removal of severely diseased leaves for the
plant; removal and destruction of fallen infected leaves)
- Moisture and humidity management (ensure good drainage,
control weeds, adequate plant spacing, pruning, minimize
leaf wetness and reduce overhead irrigation).
- Protective spray applications of approved fungicides.
- Avoid spreading the pathogen on hands and tools during
harvesting operations.
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| Notes: Noni
shot hole has not been previously reported to occur in Hawaii
or elsewhere in the world. |
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