Squash, Winter
Symptom Cause  
Water-soaked spots on leaves
Angular Leaf Spots
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Small, dark spots on leaves; eventually leaves turn black; fruits may blacken and drop
Anthracnose (on plants)
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Plants wilt quickly; white, sticky material might be seen when a stem is cut
Bacterial Wilt
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Holes in leaves; stalks; and stems
Cucumber Beetles
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Downy purple spots on leaves
Downy Mildew
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Yellowing of the leaf margins (chlorosis) is an early symptom on the plant, and light- to dark-brown spots (necrosis) can appear, plus water-soaked regions on the stem.
Gummy Stem Blight (black rot)
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Yellow-green mottling of leaves
Mosaic Viruses
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Flowers and new fruits damaged
Pickleworms
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White spots on leaves; eventually entire leaf is covered with powder; fruits ripen prematurely/poor flavor and texture
Powdery Mildew
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Sunken green spots on squash
Scab
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Large ragged holes in leaves, often in middle
Slugs
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Wilted; dried-up leaves
Squash Bugs
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Sudden wilting of plants
Squash Vine Borers
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