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Disease - a rusty problem

Updated: Jan 15, 2022

Rust (Coleosporium plumeriae)

A recent fungal problem (within the last 15 years) is the occurrence of rust.

  • The rust (Coleosporium plumeriae) fungus is the small orange pustules that appear on the back of the leaves in late summer.

  • Rust is an unsightly problem but will not kill the tree but can lead to premature defoliation.

  • Once rust pustules appear under the leaves those leaves need to be removed and can't be treated.

  • To prevent rust, treatment must be made prior to the rust appearing on the plant. We recommend using a systemic fungicide formulated for flowering ornamentals - this can either be sprayed onto the foilage to runoff or mixed into a slurry and watered directly into the roots. Best to follow the directions provided with the fungicide. In early summer, or at the first sign of a few rust pustules, start spraying the leaves and continue this on a fortnightly basis through to Autumn. This will inhibit the rust pustules from blooming and keep the plant clean from rust. If watering in with a slurry do this on a monthly basis.

  • Organically you can treat rust with a horticultural plant based oil which will reduce the rust but some rust will still appear and leaves will need to removed on a regular basis.

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