Initial disease symptoms will result in scattered sori (clustered sporangia), eventually covering the entirety of the leaf with coalescing postulates.

[1] When canna rust first appears, the affected foliage should be removed and discarded, otherwise the fungi will propagate and destroy the whole plant.

This practice can increase the aeration of the canopy, permitting more light and allowing fungicide sprays (if used) to reach the plant.

Puccinia thaliae is a systemic pathogen, in that symptoms will affect a greater part or all of the plant.

[4] The teliospores range from cylindrical, clavate to club shaped, with rounded apex and sized from 50−83 × 14−21 μm.

The canna rust fungus grows best under high relative humidity and extended periods of leaf wetness (roughly ≥20 °C).

[7][8] In North America, P. thaliae has been reported to cause rust in Canna indica in Florida and C. × generalis in Texas.

The rust lowers the value of lilies for sale and can kill canna plants that home gardeners are trying to grow themselves.