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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Vegetable > Cauliflower > Discolored head

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Cauliflower > Head > Discolored head

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  • Image: Downy Mildew 1
  • Image: Downy Mildew 2
  • Image: Downy Mildew 3

Downy Mildew
Peronospora parasitica

  • Numerous black sunken spots can form on infected heads
  • Gray-white sunken leaf spots which are often angular and restricted by the leaf veins
  • Leaf tissue around the spots turns yellow
  • Fuzzy gray growth can be seen on the underside of the leaves
  • Disease is common in cool wet weather
  • More information on Downy Mildew...
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  • Image: Black Rot 1
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  • Image: Black Rot 2

Black Rot
Xanthomonas campestris

  • Yellow V-shaped lesions develop on margin of leaves, the point of the v follows a vein towards the base of the leaf
  • As infection continues, leaves wilt, turn yellow and eventually turn brown and die
  • Black veins can be seen in infected leaves, petioles and stems
  • Sticky yellowish liquid bacterial ooze may be seen if infected veins are cut
  • Disease favored by hot, humid conditions
  • Cauliflower head turns uniformly brown when infected
  • More information on Black rot...
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  • Image: Black Leaf Spot/Gray Leaf Spot 1
  • Image: Black Leaf Spot/Gray Leaf Spot 2

Black Leaf Spot/Gray Leaf Spot
Alternaria spp.

  • Gray to black round leaf spots with concentric rings
  • Leaf tissue becomes dry, brittle and often falls out, resulting in a ‘shot hole’ appearance
  • Leaf spots often appear first on lower older leaves
  • Broccoli and cauliflower heads may develop dark brown irregular sunken areas
  • More information on Leaf Spot...
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  • Image: Calcium Deficiency 1

Boron Deficiency

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