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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Annuals and Perennials > Iris > Spots on leaves

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Iris > Spots on leaves

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  • Image: iris leaf spot 1
  • Image: iris leaf spot 2
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Iris Leaf Spot
Didymellina macrospora

  • Light yellow to tan spots with a light colored center, about 1/4 inch across
  • Tiny black dots are often visible in the light colored center of the leaf spot
  • Leaf tissue around spots may turn yellow or brown
  • In severe cases, leaf tips turn brown and bend downward
  • More information on Iris Leaf Spot...
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  • Image: iris borer 3
  • Image: iris borer 2
  • Image: iris borer 1

Iris Borer

  • Damaged rhizomes occur mid summer through fall
  • Water-soaked looking streaks in leaves may be noticed in spring
  • Yellow or brown streaks especially near the base of the leaf mid to late summer
  • Ragged brown leaf tissue at the base of the leaf, may look tattered or have sawdust like frass
  • Pinkish or whitish larva with a dark colored head, up to 1 1/2 to 2 inches long inside rhizome
  • More information on Iris Borer...
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  • Image: soft rot 1
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  • Image: soft rot 3

Bacterial Soft Rot
Erwinia carotovora

  • Leaves turn brown from the tip down with a yellow border between green and brown leaf tissue
  • Browning leaves may wilt and fall over
  • Rhizome is soft when pressed on and may smell bad
  • Inside of the rhizome is soft, mushy and smells bad
  • Common in heavy wet soils, and in rhizomes damaged by borer
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  • Image: freeze injury 1
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Freezing injury

  • Yellow to tan leaf tips of large spots on leaves
  • Affected leaf tissue turns papery thin and dry
  • Symptoms show up over night
  • Occurs early spring with a late frost
  • After cold period, new growth is healthy and normal looking

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