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Cucurbits

Note Pest Damage For Future Management–Vegetative Through Fruit

On this page
  • Charcoal rot
  • Fusarium wilt (in cantaloupe and watermelon)
  • Root knot nematodes
  • Root rot diseases
  • Sudden wilt
  • Verticillium wilt
  • Vine decline caused by Monosporascus (in melons), Macrophomina, Pythium
  • Viruses–Cucumber mosaic, Cucurbit aphid-borne yellows,
    Potyviruses, Squash mosaic virus

If you see symptoms or damage from the following, make note and manage prior to future planting.

Names link to information on identification and management.

Click on photos to enlarge
Stem damaged by charcoal rot.
Charcoal rot
Identification tip: Crown leaves yellow. As disease progresses, stem of infected plant eventually becomes dry and tan to brown. If lesion girdles the stem, the plant dies. First disease symptoms occur late in the growing season, usually within 1 to 2 weeks of harvest.
CRed-brown vascular discoloration in melon stems caused by the Fusarium wilt pathogen.
Fusarium wilt (cantaloupe)
Identification tip: Symptoms include the yellowing of a runner on one side of the plant followed rapidly by wilting of the runner.
Brown vascular discoloration in the crown of a watermelon plant caused by the Fusarium wilt pathogen.
Fusarium wilt (watermelon)
Identification tip: Symptoms are more readily seen after fruit set and may consist of dark vascular discoloration inside stems and yellowing and wilting of one runner or one side of the plant (not shown here).
Swollen, galled roots infested with root knot nematodes.
Root knot nematodes
Identification tip: Feeding causes plant roots to enlarge into galls that can be seen with the naked eye.
Brown lesions and stolon pruning (right) resulting from Rhizoctonia stem and stolon canker.
Root rot disease
Identification tip: Stem collapses and turns tan to brown, roots die, and leaves wilt.
Symptoms of sudden wilt begin with the yellowing of crown leaves.
Sudden wilt (Pythium species)
Identification tip: Symptoms typically occur from fruit set onward and consist of yellowing crown leaves that die prematurely followed by a rapid collapse of entire plants.
Wilting and discoloration of cucumber plant infected with Verticillium wilt.
Verticillium wilt
Identification tip: Wilting and yellowing of crown leaves, which eventually dry up. Gradually the wilting progresses to runner tips.

First symptoms of vine decline caused by Monosporascus cannonballus include chlorosis and necrosis of older crown leaves followed by canopy collapse.
Vine disease decline
Identification tip: Characterized by the sudden and generally uniform canopy collapse of entire fields 1 to 2 weeks before harvest.
 
Viruses
A pepper plant infected with Cucumber mosaic virus showing leaf curling and mosaic.
Cucumber mosaic
Identification tip: First symptom is clearing of veins, followed by development of mosaic patterns or mottling (alternating zones of dark green, light green, and yellow).
Cucurbit aphid-borne yellows luteovirus causes a general yellowing and eventual thickening of the older leaves with the major leaf veins remaining green.
Cucurbit aphid-borne yellows
Identification tip: This disease causes a general yellowing of older leaves, which become thick and leathery while their major veins remain green.
The first symptom of cucurbit yellow stunting disorder is a yellow spotting of leaves.
Cucurbit yellow stunting disorder
Identification tip:
First yellow spots appear on leaves, which develop into interveinal chlorosis (veins remain more or less green but the rest of the leaf turns bright yellow).
TLeaf mottling caused by watermelon mosaic virus.
Potyvirus (caused by Watermelon mosaic virus or Papaya ringspot virus)
Identification tip: The first symptom is a vein clearing, followed by development of mosaic patterns or mottling (alternating zones of dark green, light green, and yellow).
Zucchini yellow mosaic virus typically causes leaf lobes to become long and narrow.
Potyvirus (caused by Zuchinni Yellow Mosaic Virus)
Identification tip: This virus can cause leaf lobes to grow long and narrow.

Photo unavailable

Squash mosaic virus
Identification tip: Leaves may have mosaic patterns or mottling.

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