Pacific Pests, Pathogens and Weeds

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Summary

• Worldwide distribution. In tropics and sub-tropics. On many crops when colonised by insects that produce honeydew, e.g., coconut, guava, mango, soursop and ornamentals.
• Black moulds grow on honeydew discharged by sap-sucking insects – aphids, planthoppers, whiteflies, scales - onto leaves and fruits.
• The fungi do not infect the leaves, but shut out sunlight, weakening growth, causing leaves to die early, and reducing fruit quality.
• Cultural control: aim to control the insects producing honeydew. If they are protected by ants, destroy nests (use hot water); prune low hanging branches and remove weeds to stop ants reaching the insects.
• Chemical control: soaps or oils to kill sap-sucking insects; use synthetic pyrethroids against ants.