Troubleshooting
Canna 'Yellow King Humbert' problems — and how to fix them
Canna 'Yellow King Humbert' (Canna 'Yellow King Humbert') is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Canna leaf roller
Very common; caterpillars roll leaves and feed inside. Check growing tips weekly; remove manually or apply a Bt spray.
Rust (Puccinia thaliae)
Orange, powdery pustules on leaf undersides during humid summers. Remove affected leaves and avoid wetting foliage.
Slugs and snails
Damage young emerging shoots in spring. Use iron phosphate bait or copper tape around containers.
Botrytis on stored rhizomes
Mould develops if rhizomes are stored too cold and damp. Allow to dry thoroughly before placing in ventilated storage.
Virus mosaic
Irregular light-and-dark green mottling; aphid-transmitted. Control aphids; remove and destroy infected plants.
Prevent canna 'yellow king humbert' problems before they start
Most canna 'yellow king humbert' issues are care-mismatch, not bad luck. Dial in the basics:
Canna 'Yellow King Humbert' problems — FAQ
Why is my canna 'yellow king humbert' canna leaf roller?
Very common; caterpillars roll leaves and feed inside. Check growing tips weekly; remove manually or apply a Bt spray.
Why is my canna 'yellow king humbert' rust (puccinia thaliae)?
Orange, powdery pustules on leaf undersides during humid summers. Remove affected leaves and avoid wetting foliage.
Why is my canna 'yellow king humbert' slugs and snails?
Damage young emerging shoots in spring. Use iron phosphate bait or copper tape around containers.
Why is my canna 'yellow king humbert' botrytis on stored rhizomes?
Mould develops if rhizomes are stored too cold and damp. Allow to dry thoroughly before placing in ventilated storage.
Why is my canna 'yellow king humbert' virus mosaic?
Irregular light-and-dark green mottling; aphid-transmitted. Control aphids; remove and destroy infected plants.