Citrus Canker

Lesions appear as raised, corky spots, often tan to brown with a water-soaked margin and a yellow halo, on leaves, twigs, and fruit. Under severe infection, lesions can coalesce, causing defoliation and blemished fruit that affects marketability even when the interior is unaffected.

Bacteria ooze from existing lesions in wet conditions and are dispersed mainly by wind-driven rain over short distances within and between nearby trees. The bacteria enter host tissue through stomata or wounds, including wounds created by leaf-mining insects, which substantially increase infection success.

• Wind-driven rain, especially during storms, is the main driver of local spread
• Leaf-miner damage creates wounds that greatly increase infection efficiency
• Long-distance spread occurs mainly through movement of infected nursery stock, fruit, or contaminated equipment and clothing

Orange and many other citrus species and hybrids are susceptible to citrus canker, though susceptibility varies among citrus types and cultivars.

• Windy, rainy, or humid weather, especially during storms
• Presence of leaf-miner damage creating entry wounds
• Movement of infected nursery stock or contaminated equipment between groves
• Dense plantings with overlapping canopies

Because citrus canker is a regulated pest in many regions and spreads readily through wind-driven rain and contaminated material, prevention combines clean planting material, physical barriers, sanitation, and compliance with local regulations.

• Use certified, disease-free nursery stock
• Manage leaf-miner populations as part of an integrated approach
• Establish windbreaks where practical to reduce wind-driven rain spread
• Sanitise equipment and restrict movement between groves, and follow official reporting protocols where citrus canker is a regulated pest