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Stage 3 outdoor water restrictions are in effect. Learn more about how City services are impacted and what you can do during this stage.

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Bronze leaf disease

Bronze leaf disease is a fungus that infects various poplar species and hybrids, including Swedish columnar aspens and tower poplars.


Symptoms of bronze leaf disease typically appear in late summer or early fall and may only be on a few branches or leaves.

  • Infected leaves turn orange-brown to reddish-brown; colouration starts at the edges of the leaf and moves inward toward the base.
  • Dieback may occur on infected branches.
  • Browning may be observed under the bark of diseased branches.
  • Leaf veins often remain a bright green in stark contrast to the rest of the leaf.

What you can do

  • Prune out affected branches 20-30 cm into healthy wood while still attempting to maintain the tree's shape. Often, this is back to the trunk. Between each cut, sanitize your tools with a bleach-water solution (25% bleach, 75% water). Removal of dead and or dying trees is important as they will infect nearby trees as well.
  • Pick up leaf litter from under the trees as soon as they drop. Fallen leaves and pruned wood should be bagged and disposed of in the garbage only. Do not bring infected leaves and wood to Leaf and Pumpkin Composting drop-off locations. Dispose of it in the garbage or take directly to the landfill.
  • Check out What Goes Where for details on how to dispose of diseased trees and shrubs.
  • If you are unsure about how/where to prune, we recommend hiring an International Society of Arboriculture-certified arborist.
  • If you suspect bronze leaf disease in a City-owned tree, contact 311.

Good sanitation is the best method of controlling the disease. Early detection and treatment is important. Visit for healthy tree care tips.​​​​​

Learn more about tree pests and diseases in Calgary​