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 Identification tip: Green peach aphids are dark
green to yellow and have no waxy covering.
Beet armyworm Identification tip: Larva feeds in the crown area
of a young lettuce plant (in August/September plantings).
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 Identification
tip: Larvae feed primarily on the undersides
of lower leaves, skeletonizing them and contaminating them
with frass.
Silverleaf whiteflies Identification tip: Adults are tiny (less than
1/10 inch), yellowish insects with white wings (in
Aug/Sept. plantings).
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.
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.
