Cucurbits

Identify Pests and Their Damage—Fruit Development

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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)
  • Darkling beetles
  • European earwig
  • Stink bugs
  • Squash bugs (in squash, pumpkin, and melon)
  • Whiteflies
  • Armyworms
 
  • Downy mildew
  • Powdery mildew

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.
Damage to zucchini caused by western spotted cucumber beetle.
Cucumber beetle damage
Identification tip: Beetles chew holes in young fruit.
Darkling beetle adult.
Darkling beetle adult
Identification tip: Adults vary from black or bluish black to rusty brown. Do not confuse with predatory ground beetles, which prey on various soil dwelling pests.
European earwig..
European earwig
Identification tip: Adult is a slender brown insect, about 1/2 to 3/4 inch long; has pair of pincers attached to the back end of the abdomen.
Green stink bug adult and feeding injury on an immature peach.
Stink bugs
Identification tip: Adult stink bugs are distinctly shield shaped, about 1/2 inch long and either brown or long; has pair of pincers attached to the back end of the abdomen.
Adults and nymphs on squash fruit.
Squash bug (squash, pumpkin, melon)
Identification tip: Adults and nymphs suck plant juices.
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.
Larva of western yellowstriped armyworm.
Armyworms
Identification tip: The larva is almost black, with two prominent and many fine, bright yellow stripes on the side.
 
Diseases
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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