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Pests and their Damage—Planting to Rosette (Desert)

On this page
  • Green peach aphids
  • Beet armyworm
  • Cutworms
  • Seedcorn maggot
  • Silverleaf whitefly
  • Damping-off
  • Corky root
  • Lettuce dieback
  • Lettuce drop
  • Fusarium wilt
  • Herbicide damage
  • Ammonium toxicity

See also, pests of other regions: Central Valley and Central Coast.

Check for stand uniformity and wilted plants and inspect plants for pests and pest or abiotic damage. 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).

Adult cutworm
Identification tip: Larvae frequently roll into a C-shape when disturbed.

Seedcorn maggot
Seedcorn maggot
Identification tip: Larvae range from 1/5 to 1/4 of an inch in length, are white to whitish yellow, cylindrical, and taper anteriorly.

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

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.

Lettuce dieback
Lettuce dieback
Identification tip: Outermost leaves are extensively yellowed. Younger, inner leaves often remain dark green in color, but can be rough and leathery.

Powdery mildew
Lettuce drop
Identification tip: Plant death with white mycelium and sclerotia at the base of plant.

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.

Pronamide herbicide damage
Herbicide damage
Identification tip: Pronamide herbicide damage to seedlings causes yellow leaf margins.

Herbicide damage
Herbicide damage
Identification tip: Alachlor herbicide injury can result in curling and stunting of leaves.

Ammonium toxicity
Ammonium toxicity
Identification tip: Discolored vascular tissue caused by ammonium toxicity.


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Statewide IPM Program, Agriculture and Natural Resources, University of California
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