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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Vegetable > Summer Squash and Zucchini > Spots on fruit

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Summer Squash and Zucchini > Fruit > Spots on fruit

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  • Image: Anthracnose 1
  • Image: Anthracnose 2
  • Image: Anthracnose 2

Anthracnose
Colletotrichum obriculare

  • Circular sunken dark spots on fruit up to ½” across
  • Salmon colored spores form in the center of fruit spots when wet
  • Irregular brown leaf spots
  • Commonly appears mid to late season
  • Also common on melons and cucumber
  • More information on Anthracnose...
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  • Image: Scab 1
  • Image: Scab 2
  • Image: Scab 4

Scab
Cladosporium cucumerinum

  • Cucumber, summer squash, zucchini, & pumpkin have sunken fruit spots are covered with greenish black velvety fungal growth
  • Winter squash have raised corky areas around fruit infections, internal rot varies depending on resistance of variety
  • Irregular gray leaf spot with a yellow halo
  • Center of leaf spot falls out, leaves look shot holed or ragged
  • Watermelon is very resistant
  • More information on Scab...
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  • Image: Virus 1
  • Image: Virus 2
  • Image: Virus 3

Virus
Squash mosaic, cucumber mosaic, watermelon mosaic

  • Fruit may have unusual color patterns, blotches or rings but are not rotten
  • Fruit are often deformed and distorted
  • Irregular, blotchy to wavy patterns of yellows and greens on leaves
  • Plants may be stunted
  • Leaves may be distorted (sometimes fern-like), wrinkled, and curled
  • More information on Virus...
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  • Image: Angular Leaf Spot 1
  • Image: Angular Leaf Spot 2
  • Image: Angular Leaf Spot 3

Angular Leaf Spot
Pseudomonas syringae pv. Lachrymans

  • Water soaked to tan small circular spots on fruit
  • Leaves develop small, angular, brown or straw-colored spots with a yellow halo
  • Leaf spots dry and drop out, leaving irregularly shaped holes in the leaves
  • Sticky drops of whitish liquid for on the underside of the leaf when wet, dry to a crust when dry
  • More information on Angular Leaf Spot...
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  • Image: Powdery Mildew 1
  • Image: Powdery Mildew 2
  • Image: Powdery Mildew 3

Powdery Mildew
Podosphaera xanthii

  • Fruit may be blotchy or have sunscald
  • Initially pale yellow spots develop on the oldest leaves
  • White to gray powdery felt in spots, blotches or complete covering of leaves
  • Lesions develop on underside of leaves, or on shaded leaves first
  • Older leaves infected first
  • Severe infection can cause leaves and vines to wither and die
  • More information on Powdery Mildew...
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  • Image: Phytophthora Blight 1
  • Image: Phytophthora Blight 2
  • Image: Phytophthora Blight 3

Phytophthora Blight
Phytophthora capsici

  • Fruit develop soft, water-soaked lesions which expand to large sections of the fruit
  • Infected fruit are soft, easily punctured and often collapse
  • Infected fruit are covered with white fungal growth
  • Large irregular brown spots on leaves
  • Stem and leaf petiole lesions are light to dark brown, water soaked and irregular
  • The entire plant may collapse if root and crown rot occurs
  • More information on Phytophthora Blight...

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