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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Vegetable > Onion > Leaves yellow then wilt

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Onion > Leaves > Leaves yellow then wilt

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  • Image: Fusarium Basal Rot 1
  • Image: Fusarium Basal Rot 2

Fusarium basal rot
Fusarium oxysporum f.sp. cepae

  • Leaves turn yellow to brown from the tip down and wilt
  • Onion bulb has watery brown decay starting at the base and extending up into the bulb
  • Roots are rotted or absent and the bulb is often easily pulled from the ground
  • A white fuzzy growth can often be seen on the rotted basal plate
  • More information Fusarium Basal Rot ...
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  • Image: White Rot 1

White rot
Sclerotium cepivorum

  • In severely infected plants, leaves may be stunted, yellow from the tip down, and die
  • Bulb has white, fluffy fungal growth
  • Small, hard, black poppy seed like fungal structures form on infected bulbs
  • More information White Rot ...
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  • Image: Soft Rot 1
  • Image: Soft Rot 2
  • Image: Soft Rot 3

Soft rot
Erwinia carotovora pv. Carotovora

  • Leaves of onions become pale and wilt
  • One or several bulb scales may appear water soaked, gray and soft
  • The entire bulb may be soft and watery
  • A foul smell may be present
  • Common on plants injured by onion maggot or other means
  • Disease develops in warm wet weather, often at the end of the season
  • More information on Soft Rot ...
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  • Image: Pink Rot 1
  • - CLICK PHOTO TO ENLARGE -

Pink root
Phoma terrestris

  • Leaves turn yellow with a reddish tinge from the tip down due to root damage
  • Sunken dark pink to maroon areas on roots
  • Infected roots break off easily
  • Plants are stunted and may produce no to very small bulbs
  • Commonly occurs mid to late season, in areas with poor soil
  • More information on Pink Root ...
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  • Image: Onion Maggot 3
  • Image: Onion Maggot 1
  • Image: Onion Maggot 2

Onion maggot
Delia antiqua

  • Onions yellow and wilt, sometimes rapidly
  • Holes in onion bulbs are present
  • Maggots may be present; they are carrot-shaped, legless, and cream colored
  • More information on Onion Maggot ...
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  • Image: : Bot Leaf Blight 2
  • Image: : Bot Leaf Blight 1

Botrytis leaf blight
Botrytis squamosa

  • Leaves develop small white circular to elliptical spots surrounded by a light green to silvery white halo
  • Centers of the spots usually become sunken, straw colored, and may break apart in a lengthwise slit
  • Bulbs are not directly infected but may be smaller on plants with severe leaf damage
  • In cool (54-75F) wet weather, disease develops rapidly, entire plants dieback starting with the oldest leaves first
  • More information on Botrytis Leaf Blight ...
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  • Image: Downy Mildew 2
  • Image: Downy Mildew 3
  • Image: Downy Mildew 1

Downy mildew
Peronospora destructor

  • Leaves develop elongated pale green to tan spots
  • Purplish gray fuzzy growth develops on leaves
  • Severely infected leaves collapse and die
  • Plants may produce small bulbs
  • Disease is most severe in cool wet weather
  • More information Downy Mildew ...
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  • Image: Stem and Bulb Nematode 1
  • Image: Stem and Bulb Nematode 2

Stem and bulb nematode
Ditylenchus dipsaci

  • In severe infestations, plant may wilt and die
  • Leaves are twisted and stunted
  • Bulbs are often desiccated and light weight, secondary rot organisms like soft rot may invade and rot the bulb
  • Outer layer of bulb is split or has cracks
  • More information on Stem and Bulb Nematode ...
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  • Image: Northern Root Knot Nematode

Northern root knot nematode
Meloidogyne hapla

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