Pests and Diseases 
Thrips (Heliothrips haemorrhoidalis)
Damage to noni leaf caused by feeding injury due to the greenhouse
thrips, Heliothrips haemorrhoidalis |
Close-up of thrips damage on the underside of a noni leaf. Adult
thrips and black fecal specks may be visible to the unaided
eye. |
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Pest: Thrips, the greenhouse thrips (Heliothrips haemorrhoidalis).
Damage: Thrips feed on noni leaves with their mouth parts. Injured tissue takes on a silvery or bleached appearance and eventually turns a bleached and then dark brown color. Large lesions may develop on leaves, with bleached centers and irregular margins. Feeding on leaf tips may result in wilting and curling. Severely affected leaves may defoliate prematurely. Yellow, chlorotic areas may surround or be associated with visible lesions. The undersides of affected leaves also may have large necrotic areas and silvery bleached regions that are spotted with small black fecal specks.
Distribution: The greenhouse thrips is widely distributed throughout Hawaii. However, significant damage to noni is usually found only where noni seedlings are grown in shadehouses or greenhouses.
Impact: Thrips are not a significant problem for noni in outdoor, field plantings. Thrips have the most negative impacts on the growth of noni seedlings in nurseries in covered shadehouse or greenhouses.
Control:
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- Leaf pruning. Detach and remove severely diseased leaves and destroy them.
- Spay applications of approved insecticides. At this time, no insecticides are registered for use on noni that are effective for thrips management.
- Move affected noni plants to an outdoor location. The thrips populations will then decline due to the presence of their natural enemies and a less conducive and protected environment.
- Weed control, and/or elimination of any alternate hosts for thrips.
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| Notes:
Thrips were not previously reported as a pest of noni in Hawaii
or elsewhere in the world. Be advised that heavy use of insecticides
may eliminate populations of beneficial insects. |
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