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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Annuals and Perennials > Bee Balm (Monarda) > Spots on leaves

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Bee Balm (Monarda) > Spots on leaves

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  • Image: Powdery Mildew 1
  • Image: Powdery Mildew 2
  • Image: Powdery Mildew 3

Powdery mildew
Erysiphe cichoracearum

  • Powdery, fluffy white spots and blothces on leaves, stems, and flower parts
  • Tiny black round spheres may be visible within white spots late in the season
  • Spots typically start on lower leaves but can spread to cover the entire plant
  • Severely infected leaves may be completely covered in white or grayish white fungi
  • In some cases, leaves become curled or twisted or turn yellow due to the infection
  • More information on Powdery mildew...
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  • Image: fourline bug 1
  • Image: fourline bug 2
  • Image: fourline bug 3

Fourlined plant bug

  • Occurs May to early July
  • Feeding causes brownish or sunken spot on leaves
  • Nymphs are red or red and black; Adults are greenish yellow with 4 black stripes, 1/4 to 1/3 inch long
  • More information on Fourlined plant bug...
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  • Image: rust 1
  • Image: rust 2
  • Image: rust 3

Puccina angustata and Puccinia menthae

  • Small yellow spots that merge to form large yellow areas on upper side of leaf
  • Dead brown blotches on severely infected areas
  • Raised orange pustules on the underside of the leaves
  • Powdery orange spores rub off of the underside of infected leaves and can be seen with a white tissue paper
  • Spots typically start on lower leaves but can spread to cover the entire plant
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  • Image: southern blight 1
  • Image: southern blight 2
  • Image: southern blight 3

Southern Blight
Sclerotium rolfsii

  • Leaves turn yellow then brown from the edges inward and wilt
  • The base of the stem may be brown or discolored
  • Tiny tan to reddish brown hard spheres and white cottony growth can be seen at the base of infected leaves or in the soil around infected plants
  • Often seen after warm wet weather
  • More information on Southern Blight...

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