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Cucurbits

Identify Pests and Their Damage—Vegetative Stage

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Arthropods Diseases
  • Cabbage looper
  • Cucumber beetle adults (especially in honeydew, crenshaw, and casaba melons)
  • Cutworms (in honeydew, crenshaw, and casaba melons)
  • Green peach aphid
  • Leafminers
  • Melon aphid
  • Spider mites
  • Squash bugs (in squash, pumpkin, and melon)
  • Whiteflies
  • Downy mildew
  • Powdery mildew

Monitor for the following pests or their damage. Manage as needed according to the Cucurbits Pest Management Guidelines.

Names link to information on identification and management.

Click on photos to enlarge
Arthropods
Cabbage looper larva.
Cabbage looper
Identification tip: A green caterpillar with a narrow white stripe along each side and several narrow lines down the back; has a characteristic arch as it crawls.
Monitoring tip: Monitor adult flights with pheromone traps and observe egg laying to time treatments.
Chewing damage to cotyledons and leaves of a honeydew melon seedling caused by western striped cucumber beetle.
Cucumber beetle damage
Identification tip: Adults chew leaves.
Black cutworm larva.
Cutworm
Identification tip: The mature larva is robust, about 1-1/2 inches long, with brown or gray mottled skin. It tends to curl into a C-shape when disturbed.
Green peach aphids.
Green peach aphid adults
Identification tip: Adults are slender in form and light green or yellowish. The winged form is pale or bright green and black, with a large dusky blotch on top of the abdomen.
Adult leafminer feeding punctures (bottom) and mines (top).
Leafminer damage
Identification tip: Larvae mines between the upper and lower leaf surfaces, creating winding white tunnels that widen as the larva grows.
Adult cotton aphid (melon aphid).
Melon aphid adults
Identification tip: Adults are round and yellowish (right) or greenish black with ridges (left). There are winged and wingless forms.
Crop damaged by twospotted spider mites.
Spider mite damage
Identification tip: Feeding causes leaves to become pale and stippled. As feeding progresses leaves dry up and die.
Squash bug feeding causes parts of vines to wilt and die.
Squash bug damage
Identification tip: Under heavy squash bug feeding, plants begin to wilt, and the point of attack becomes black and brittle (not shown here).
Healthy squash leaf (left) and silvering leaf caused by whitefly feeding.
Whitefly damage (silverleaf whitefly) Identification tip: Feeding frequently causes leaves to turn whitish or silver. It is important to distinguish silverleaf whiteflies from other species.
Diseases/Nematodes
Downy mildew on cucurbits, caused by Pseudoperonospora cubensis, appears as pale green to yellow angular spots.
Downy mildew
Identification tip: First appears as small, pale green to yellow, angular spots between the veins. Eventually the spots coalesce and the leaf will turn brown.
Powdery mildew on melon leaves.
Powdery mildew
Identification tip: This disease first appears as pale yellow spots. Spots enlarge as white, fluffy mycelium grows over plant surfaces producing spores and giving lesions a powdery appearance.
 

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