Pacific Pests, Pathogens and Weeds

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Summary

• Worldwide distribution. On lemon, rough lemon and mandarin. Other species of citrus - grapefruit, orange and pomelo - are also susceptible, but less so. An important disease.
• The fungus distorts the leaves and makes the fruit unsightly. It stunts common rootstocks in the nursery, so they are difficult to bud.
• Similar to citrus canker (see Fact Sheet no. 091), except leaves are stunted, wrinkled with torn margins.
• Spread is by wind and rain, by insects, on nursery plants, and fruits.
• Cultural control: make nurseries at distance from production areas; prune to keep open canopy, and improve air circulation.
• Chemical: in the nursery, use copper or chlorothalonil at the beginning of leaf flushes.