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Pests and their Damage—Planting to Rosette (Central Valley)

On this page
  • Green peach aphid
  • Beet armyworm
  • Corn earworm
  • Loopers
  • Silverleaf whitefly
  • Corky root
  • Fusarium
  • Lettuce drop
  • Damping off (Rhizoctonia diseases)
  • Ammonium toxicity
  • Tomato spotted wilt

See also, pests of other regions: Central Coast and Desert. Names link to more information on identification and management.

Click on photos to enlarge

Green peach aphids
Green peach aphids
Identification tip: Green peach aphids are dark green to yellow and have no waxy covering.

Beet armyworm larva feeding on lettuce crown
Beet armyworm
Identification tip: Larva feeds in the crown area of a young lettuce plant (in August/September plantings).

Green peach aphids
Corn earworm
Identification tip: Larvae have discrete rows of tubercles with one or two protruding hairs along their backs. As larvae mature they develop distinct stripes, but the overall color is variable.

Looper damage to lettuce
Looper damage
Identification tip: Larvae feed primarily on the undersides of lower leaves, skeletonizing them and contaminating them with frass.

Silverleaf whiteflies
Silverleaf whiteflies
Identification tip: Adults are tiny (less than 1/10 inch), yellowish insects with white wings (in Aug/Sept. plantings).

Corky root
Corky root damage
Identification tip: Young corky root infected lettuce plant showing banding of green to tan areas on tap and lateral roots.

No photo available.

Fusarium wilt
Identification tip: Leaves turn yellow and develop tipburn. The vascular system is brown to black in the leaves and a reddish brown discoloration develops in the cortex of the crown and upper root. Plants may be stunted and fail to form heads.
Ammonium toxicity
Ammonium toxicity
Identification tip: Discolored vascular tissue caused by ammonium toxicity.
Lettuce drop
Lettuce drop
Identification tip: Plant death with white mycelium and sclerotia at the base of the plant.
No photo available.

Damping-off (Rhizoctonia diseases)
Identification tip: Infected seedlings exhibit decayed roots and brown lesions on stems. When seedlings are infected, the stem tissue collapses and plants fall over and die.
Tomato spotted wilt virus
Tomato spotted wilt
Identification tip: Iceberg lettuce develops necrotic lesions on leaves.

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