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

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Summer Squash and Zucchini > Fruit > Rotten 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: Choanephora Rot 1
  • Image: Choanephora Rot 2
  • Image: Choanephora Rot 3

Choanephora Rot
Choanephora cucurbitarum

  • Blossom end of squash is soft, rotted and covered in fluffy purplish black fungal growth
  • Flowers are covered with first white then purplish black fungal growth
  • Occurs after wet weather
  • Most common in squash
  • More information on Choanephora Rot...
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  • Image: Gummy Stem Blight and Black Rot 1
  • Image: Gummy Stem Blight and Black Rot 3
  • Image: Gummy Stem Blight and Black Rot 4

Gummy Stem Blight and Black Rot
Didymella bryoniae

  • Fruit rot initially looks water soaked and eventually turns completely black
  • Tiny black dots can be seen in fruit infections
  • Fruit infection often starts on the side of the fruit touching the soil
  • Fruit often collapse due to other rotting organisms
  • Leaf symptoms vary from browning at leaf edges and between veins to circular tan to brown spots
  • Yellow halos may occur around leaf spots and older spots are often dry and cracked
  • Tan lesion on stems, often with black spots and dark gummy exudate
  • More information on Gummy Stem Blight and Black Rot...
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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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  • Image: White Mold 1
  • Image: White Mold 2
  • Image: White Mold 3

White Mold
Sclerotinia sclerotiorum

  • Fruit becomes rotted and watery
  • White cottony mold on squash
  • Small hard, black raisin like fungal structures embedded in cottony mold
  • Most common on pumpkin and some winter squash
  • More information on White Mold...

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