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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Elm > Leaves partially or completely brown

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Elm > Leaves > Leaves partially or completely brown

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  • Image: Dutch elm disease 1
  • Image: Dutch elm disease 2
  • Image: Dutch elm disease 3

Dutch elm disease
Ophiostoma ulmi and Ophiostoma novo-ulmi

  • Leaves turn yellow, wilt or shrivel, turn brown, then fall off the branch
  • Initial infection occurs on one branch; disease may quickly progress to all branches
  • Peel back bark on symptomatic branch to reveal brown streaking on wood
  • Healthy elms neighboring infected elms soon show symptoms due to spread through root grafts
  • Wood pecker holes with bark loss is common on trees killed by Dutch Elm Disease
  • American, red or slippery and rock elm are highly susceptible
  • More information on Dutch elm disease...
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  • Image: Elm leafminer 1
  • Image: Elm leafminer 2
  • Image: Elm leafminer 3

Elm leafminer
Kaliofenusa ulmi

  • Feed inside leaves, first appearing as serpentine mines and gradually coalescing to give the appearance of brown blotch-like mines between leaf veins
  • Damaged leaves may remain on the tree throughout the growing season
  • Larvae are translucent white, legless, and are present inside leaves in late spring
  • Siberian and red elm are most commonly affected
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  • Image: Elm yellows 1
  • Image: Elm yellows 2
  • Image: Elm yellows 3

Elm yellows or Elm phloem necrosis
Elm yellows group or clover proliferation group

  • Occasionally, leaves can shrivel, turn brown and remain attached to branches for several weeks
  • Leaves in the entire canopy turn yellow, droop and fall off, often all in a few weeks time
  • When bark is peeled back, the inner bark is yellow brown and smells of wintergreen (American elm) or maple syrup (red elm)
  • Witches’ broom or dense leaf clusters at branch ends, common on red elms
  • Damage appears mid to late summer; infected trees die within a year or two
  • All Minnesota elm species are susceptible
  • More information on Elm yellows...
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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, wilt and die in severe infections
  • Leaves are small and yellowed in chronic infections
  • Leaf symptoms are often seen on only one branch in the canopy
  • Dark brown to black streaks often 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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  • Image: Stem girdling roots 1
  • Image: Stem girdling roots 2
  • Image: Stem girdling roots 3

Stem girdling roots

  • Affected trees commonly exhibit excessive and abnormal winter damage including frost cracks and dieback
  • Affected trees are often stunted, exhibit poor summer color, change color and lose their leaves early in the fall
  • A root circling the trunk of the tree may be seen at the soil line
  • Trunk may become sunken in or compressed where it contacts the root
  • If girdling root is below ground, the trunk will lack the natural widening or flare at the soil line so will go straight into the earth like a telephone pole; trees often exhibit an abnormal lean
  • Affected trees commonly exhibit water-stress symptoms such as marginal leaf scorch, wilting, sudden leaf fall
  • More information on Stem girdling roots...
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  • Image: Elm leaf beetle 1
  • Image: Elm leaf beetle 2
  • Image: Elm leaf beetle 3

Elm leaf beetle
Pyrrhalta luteola

  • Entire leaf canopy can be affected so may look brown from a distance
  • During late spring larvae windowpane feed, i.e. eat one layer of leaf tissue between the veins leaving the upper leaf surface intact
  • Adults eat small, nearly circular holes in the leaves during spring
  • Adults are ¼ to 3/8 inch long and yellow with black stripes along length of wing covers
  • Larvae up to 1/2 inch long; dull yellow with lateral black stripes
  • Siberian elms are most preferred host followed by American elms
  • More information on Elm leaf beetle...
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  • Image: Deicing salt injury 1

Deicing salt injury

  • Soil salt damage causes leaf edges or margins to appear burnt or scorched progressing toward the mid-vein
  • Salt spray causes branches to become tuft-like (a.k.a. witches’ broom)
  • Run-off salt kills roots which results in die-back of most branches
  • Affected trees leaf out later than other non-infected trees
  • More severe on branches that face the road
  • Damage most noticeable in spring
  • More information on Deicing salts...
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  • Image: Elm flea weevil 1
  • Image: Elm flea weevil 2
  • Image: Elm flea weevil 3

Elm flea weevil
Orchestes alni

  • Larvae create blotch mines at tips of leaves
  • Adults eat on leaf undersides creating small holes in leaves
  • Adults are brown with black heads, black spots on wings, long snout, 1/8 inch long
  • Preferred hosts are Siberian and hybrid elms
  • Currently only known in St. Paul
  • More information on Elm flea weevil...

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