Pacific Pests, Pathogens and Weeds

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Summary

• Worldwide distribution. In Australia, New Caledonia, New Zealand.
• Serious fungal disease of Myrtaceae causing spots, distortions, defoliation, dieback and death depending on species. Major threat to native environments.
• Pustules (uredinia) on foliage and flowers, sometime purplish borders, producing masses of vivid yellow spores (urediniospores); occasionally, another thick-walled survival spore (teliospores) forms in the pustules on underside of leaves.
• Spread: spores on the wind; rain splash; on clothing, vehicles, animals, and the trade in wood and live plants.
• Biosecurity: difficult because wind dispersed, but regulation of movement of plant hosts important.
• Cultural control: regulate plant nurseries; avoid replanting susceptible species; hygiene measure (clothing, tools, vehicles) avoiding transfer of spores to healthy areas.
• Chemical control: strobilurin and sterol biosynthesis inhibitor (SBI) fungicides registered in Australia. Copper and mancozeb fungicides also likely effective.