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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Prunus > Leaves discolored yellow to brown

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Prunus > Leaves > Leaves discolored yellow to brown

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  • Image: Black knot 1
  • Image: Black knot 2
  • Image: Black knot 3

Black knot
Apiosporina morbosa

  • Lumpy olive to black elongate swellings along all sizes of twigs
    and branches
  • Gall formation may cause leaves to wilt or not leaf out showing branch dieback
  • Rough black cracked swelling can occur on the main trunk
  • Most common on choke and pin cherry
  • More information on Black knot...
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  • Image: Branch cankers 1
  • Image: Branch cankers 2
  • Image: Branch cankers 3

Branch cankers
Valsa leucostoma, Leucostoma spp.

  • Leaves on random branches wilt, turn yellow then brown
  • Cankers are brown to black sunken areas on branch that may have cracked bark and discolored reddish brown sapwood
  • Sticky gum exudes from branch cankers
  • Infected branches don't leaf out in spring
  • Random dead branches seen throughout canopy
  • Raised black pimple like fungal structures form on cankers and dead branches, exude orange tendrils of spores in wet weather
  • Common on trees stressed by drought, winter injury, wounds, insect feeding or other factors
  • More information on Branch cankers...
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  • Image: Leaf spot 1
  • Image: Leaf spot 2

Leaf spot
Blumeriella jaapii

  • Leaves with multiple spots turn yellow and fall off prematurely
  • Spots grow together, causing large parts of the leaf to turn brown
  • Purple to reddish brown spots that are up to 1/10th inch diameter
  • Leaf spots dry up and fall out, leaving holes in the leaf, leave appear to have shot holes
  • Damage first seen in late spring, early summer
  • More information on Leaf spot...
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  • Image: Brown rot 1
  • Image: Brown rot 2
  • Image: Brown rot 3

Brown rot
Monilinia fructicola

  • Sudden browning of blossoms or wilting of leaves
  • Sunken, darkened areas on twigs from which gums are exuded, also known as gummosis
  • Part or all of the ripening fruit develop a soft brown rot, then become shriveled and dusted with powdery tufts of tan to gray spores
  • Rotten fruit may remain attached to the tree or fall to the ground
  • More information on Brown rot...
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  • Image: Leaf curl 1
  • Image: Leaf curl 2

Leaf curl
Taphrina wiesneri

  • Leaves have thick puckered to curled spots that are yellow to reddish brown
  • Diseased leaves droop, turn brown and die as the disease progresses
  • Witches brooms, clusters of small twigs arising from a swollen area of the branch, form on some infected trees
  • Common on wild cherry trees
  • More information on Leaf curl...
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  • Image: Verticillium Wilt 1
  • Image: Verticillium Wilt 2
  • Image: Verticillium Wilt 3

Verticillium Wilt
Verticillium dahliae

  • Leaves turn brown from the edges and tips, then wilt and die in severe infections
  • Leaf symptoms are often seen on only one or a few random branches in the canopy
  • Leaves are small and yellowed in chronic infections
  • Dark streaks can be seen in the sapwood if the bark is peeled back, appearing as rings or arcs in a cross cut
  • Symptoms may develop over a single growing season, or over several years
  • More information on Verticillium Wilt...

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