Septoria canker
- Found on a variety of poplars across North America
- Hybrids and non natives hit worse
- Also present in natives and aspens
- Leaf infections occur soon after attaining full size
- More conspicuous on lower branches
- Leaf spots approximately two months later, pencil size black spots
- Cankers on leaf affected trees
- Canker diseased bark is black, often brown toward center of canker
- Shoots may be girdled, lower branches mostly affected.

(Photo credit: “Septoria apiicola a1 (2)" by Jerzy Opiola (Selso), licensed under CC BY-SA 4.0.)