Diagnostic Key:Diseases of Cucurbit Leaves |
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| Diseases causing symptoms on cucurbit leaves | |
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Bacteria Phytoplasma |
Fungi/oomycete
Miscellaneous |
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Angular leaf spot: Leaves |
Leaf Symptoms Present |
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Brown spots, angular in shape (restricted by small veins), often with yellow haloes. Young spots are water-soaked. Older spots have holes in center. Scab causes similar symptoms on leaves. Stems, petioles and fruits develop water-soaked spots that become covered with a white crust. |
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Bacterial leaf spot: Leaves |
Leaf Symptoms Present |
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Leaf spots much smaller than those of Angular leaf spot, and initially may be over looked. The veins do not define the lesion shape, and the yellow margin is indefinite. Fruit lesions vary in size, and may progress into flesh of fruit, causing them to rot. | ||||||||||||
Bacterial Wilt: Leaves |
Leaf Symptoms Present |
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Alternaria leaf blight: Leaves |
Leaf Symptoms Present |
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Brown spots, 0.5-5 mm or larger in diameter, with yellow halo. Spots often have concentric rings (target appearance). Uncommon. | ||||||||||||
Anthracnose: Leaves |
Leaf Symptoms Present |
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Tan to brown oval spots with pycnidia. Spots may have light centers. Spots on stems and petioles (shallow, elongated, tan) and also on fruit. | ||||||||||||
Downy mildew: Leaves |
Leaf Symptoms Present |
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Brown spots, angular in shape (restricted by small veins). Young spots are pale-green then yellow on upper surface. Purplish or gray spores form on under leaf surfaces. Leaves turn brown and die but remain erect, resembling frost injury. | ||||||||||||
Gummy stem blight: Leaves |
Leaf Symptoms Present |
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Leaf spots are uncommon on pumpkin. Occasional marginal necrosis and large, wedge-shaped necrotic areas. Yellow haloes may occur. Older spots are often dry and cracked. Spots and streaks on stems, sometimes with gummy exudate. Pycnidia on leaves and stems. Fruit rot phase called black rot. Localized occurrence in region. | ||||||||||||
Phytophthora crown rot: Leaves |
Leaf Symptoms Present |
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Dark brown leaf spots, up to 5 cm in diameter. Plant decline and fruit rot are more common symptoms. Localized occurrence in field and in region. | ||||||||||||
Plectosporium blight: Leaves |
Leaf Symptoms Present |
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Light tan spots, small, spindle-shaped, sunken, dry, scabby. Spots on main leaf veins and sometimes leaf blades, also on stems, petioles, fruit handles, and sometimes fruit.
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Powdery mildew: Leaves |
Leaf Symptoms Present |
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White, powdery-like spots appearing first on the under surface of older leaves. Also on upper leaf surfaces. | ||||||||||||
Septoria leaf spot: Leaves |
Leaf Symptoms Present |
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White or beige spots, circular, 1-2 mm or larger in diameter, with narrow brown border. Brown water-soaked spots under wet conditions. Older spots usually are cracked and have a few pycnidia. Fruit symptoms also. | ||||||||||||
Scab: Leaves |
Leaf Symptoms Present |
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Brown spots, angular in shape (restricted by small veins), often with yellow haloes. Young spots are pale-green and water-soaked. Older spots have holes in center. Angular leaf spot causes similar symptoms. Symptoms also occur on petioles, stems and fruit. | ||||||||||||
Ulocladium: Leaves |
Leaf Symptoms Present |
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Miscellaneous: Leaves |
Leaf Symptoms Present |
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Ozone injury: Leaves |
Leaf Symptoms Present |
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PHOTO Symptoms shown on pumpkin |
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White spots, circular, 1-3 mm in diameter, distributed throughout the crop on mid-aged leaves. Localized to regions near source of ozone (e.g. large urban areas) | ||||||||||||
Unknown: Leaves |
Leaf Symptoms Present |
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Aster yellows: Leaves |
Leaf Symptoms Present |
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Yellowing of young leaves, proliferation of secondary shoots, and rigid, erect growth habit. Fruit symptoms also. Uncommon. | ||||||||||||
Viruses: Leaves |
Leaf Symptoms Present |
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Leaves mottled, distorted (sometimes fern-like), wrinkled, curled, dwarfed. Plant stunted. Fruit symptoms also. | ||||||||||||
Diagnostic Key —Cucurbit: Wilt and General Plant Decline and Crown Area
Diagnostic Key —Cucurbit: Diseases of Fruit
