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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous > Cotoneaster > Leaves discolored white, yellow or pale green

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Cotoneaster > Leaves > Leaves discolored white, yellow or pale green

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  • Image: Codling moth 1
  • Image: Codling moth 2
  • Image: Apple Scab 3

Two-spotted spider mite
Tetranychus urticae

  • White to yellow stippling on foliage
  • Heavy infestations will cause leaves to turn white, yellow and ultimately grayish bronze
  • Premature leaf drop may occur
  • Mites usually appear in late June to August; they are more prevalent in hot, dry weather
  • Adult spider mites are small (approximately 1/50 inch long) and are hard to see; they are yellow to dark red with dark spots (need magnification to see)
  • Shake leaves over white paper or plate to detect mites- adults are dark and move slowly
  • More information on powdery mildew...
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  • Image: Codling moth 1
  • Image: Codling moth 2
  • Image: Apple Scab 3

Powdery Mildew
Podosphaera clandestina

  • Patches of white, powdery or felt-like fungal patches on leaf surfaces
  • Leaves and shoots may be puckered or distorted
  • New leaves and shoots may be smaller than normal
  • Powdery white fungal growth may be present on ripened berries
  • Symptoms may develop over a single season, or over several years
  • More information on powdery mildew...
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  • Image: Fire Blight 1
  • Image: Fire Blight 2
  • Image: Fire Blight 3

Hawthorn Lacebug
Corythuca cydoniae

  • Feed on underside of leaves causes yellowish pin-prick stippling on upper surface
  • Small drops of varnish-like excrement is found on underside of leaves
  • Heavy feeding may cause damaged areas to coalesce forming blotches
  • Active throughout the growing season, although damage is most noticeable during late summer
  • Adults are .125 to .25 inches long, have light colored bodies with black bands with ornately sculptured wings that are flat and lacey from above.
  • More information on Hawthorn Lacebug...
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  • Image: Black Rot 1
  • Image: Black Rot 2
  • Image: Black Rot 3

Oystershell scale
Lepidosaphes ulmi

  • Light to moderate infestations show little or no symptoms
  • Severe infestations can cause chlorotic, stunted foliage
  • Dieback and cracked bark can result from heavy infestations
  • Light to dark brown, elongated, 1/10 to 1/8 inch long oyster-shell shaped scales found on bark
  • More information on Oystershell scale...

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