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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Annuals and Perennials > Marigold > Leaves discolored brown to black

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Marigold > Leaves > Leaves discolored brown to black

1 of 4
  • White mold 1
  • White mold 2
  • White mold 3

White Mold
Sclerotinia sclerotiorum

  • Entire plant or single branch wilts, leaves turn brown and die
  • Wilted stems are discolored, tan to off-white
  • Fluffy, white cotton-like fungal growth may been seen on infected plants when humidity is high
  • Black hard spheres ranging in size from 1/16 to ½ inch can be found clinging to the outside an infected stem or embedded inside the dead stem
  • Entire plant or single branch wilts, leaves turn brown and die
  • More information on white mold
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  • Root rot 1
  • Root rot 2
  • Root rot 3

Root rot
Rhizoctonia solani and Pythium spp.

  • Leaves turn yellow and wilt
  • Plants are stunted
  • The base of the stem may turn brown and crack
  • Roots have brown sunken areas and lack root hairs
  • The outer root tissue may be easily removed leaving behind thin, stringy root cores
  • Disease favors cool, wet soil with poor drainage
  • Lab test necessary to distinguish between Rhizoctonia and Pythium Root Rot
  • More information about Rhizoctonia root rot
  • More information about Pythium root rot
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  • Gray mold 1
  • Gray mold 2
  • Gray mold 3

Gray Mold
Botrytis cinerea

  • Irregular brown spots on leaves
  • Brown blossoms or petals; flowers drop off prematurely
  • Gray fuzzy mold develops on rotted tissue under humid conditions
  • Disease develops during cool, wet weather
  • More information on gray mold
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  • Cold damaged plant 1
  • Cold damaged flowers 2
  • Cold damaged plant 3

Cold Damage

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