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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Oak > Brown spots or blotches on leaves

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Oak > Leaves > Brown spots or blotches on leaves

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  • Image: Oak anthracnose 1
  • Image: Oak anthracnose 2
  • Image: Oak anthracnose 3

Oak anthracnose
Discula quercina

  • Leaves have scattered brown, irregular spots that can coalesce into nearly completely brown leaves
  • Affected leaves become wrinkled, cupped or curled especially around leaf edges
  • On severely infected trees, leaves fall off early in the season, trees soon sends out new leaves
  • Damage is most common on lower and interior branches
  • Damage most common in spring as leaves are growing during wet weather
  • Most affected are trees within white oak group (white oak, bur oak, swamp white oak)
  • More information on Oak anthracnose
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Bur oak blight
Tubakia iowensis

  • Infects only bur oaks - small acorn variety
  • Spring and early summer, leaf veins on lower leaf surface have dark brown dots or short lines
  • Mid-summer and fall, random lengths of leaf vein turn brown; some expand into brown wedge shaped areas on leaves
  • Leaves may turn completely brown, some drop early
  • Small raised black dots form on the petiole (stem) of infected leaves
  • Some leaves remain attached through winter
  • Symptoms appear in lower, inner canopy first. Disease progresses upward and outward over multiple seasons
  • More information on Bur oak blight
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  • Image: Jumping oak gall wasp 1
  • Image: Jumping oak gall wasp 2

Jumping oak gall wasp
Neuroterus saltatorius

  • Leaf upper surface has brown spots, 1/16 to 1/8 inch diameter, encircled by yellow halo
  • Growths the size of BBs or small seeds on leaf undersides
  • Foliage can be discolored or turn brown when leaves heavily infested
  • Can cause premature leaf loss
  • Commonly associated with white oaks
  • More information on Jumping oak gall wasp
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  • Image: Oak leaf miner 1
  • Image: Oak leaf miner 2
  • Image: Oak leaf miner 3

Oak leaf miner
Cameraria spp.

  • Larvae feed between leaf surfaces creating blotch-like mines
  • Canopy looks brown when heavily infested; defoliation can occur
  • Larvae 1/4 inch long with bodies that taper to rear, although larvae are rarely seen
  • Primarily attacks white oak
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  • Image: Oak slug sawfly 1
  • Image: Oak slug sawfly 2
  • Image: Oak slug sawfly 3

Oak slug sawfly
Caliroa quercuscoccineae

  • Larvae windowpane feed underside of leaf, i.e. chew leaf one layer of leaf tissue between the veins creating a lacelike appearance
  • Larvae is dark green to black and covered in slime; adult is non-stinging wasp that is rarely seen
  • Damage first visible early summer
  • Pin oak and black oak are preferred hosts
  • More information on Oak slug sawfly
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  • Image: Oak leaf blister 1
  • Image: Oak leaf blister 2
  • Image: Oak leaf blister 3

Oak leaf blister
Taphrina caerulescens

  • Raised blister-like leaf spots; appear sunken from the underside of the leaf
  • Leaf blisters are initially pale green to orange, but turn brown with age
  • Blister areas range from 1/16 to 1/2 inch in length
  • Heavy infestation will cause leaf to curl after the blisters have merged together
  • Leaves do not drop
  • Damage most common in spring as leaves are growing during wet weather
  • More information on Oak leaf blister
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  • Image: Tubakia leaf spot 1
  • Image: Tubakia leaf spot 2
  • Image: Tubakia leaf spot 3

Tubakia leaf spot
Tubakia dryina

  • ¼ to ½ inch sized leaf spots or blotches that are dark brown or reddish-brown
  • Spots often restricted by leaf veins; defoliation occurs if infection is severe
  • In severe cases, the canopy appears full of brown leaves
  • Symptoms first present mid-summer but become most obvious late summer
  • All oaks are susceptible
  • More information on Tubakia leaf spot

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