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Lettuce
> Year-Round IPM Program > Heading
to Harvest > Pest
Damage (Central Valley)
Lettuce
Pests and their Damage—Heading to Harvest (Central Valley)
On this page
- Armyworms
- Loopers
- Corn earworm
- Green peach aphids
- Botrytis crown rot
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- Big vein
- Lettuce dieback
- Powdery mildew
- Lettuce drop
- Tip burn
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- Anthracnose
- Corky root
- Lettuce chlorosis
- Tomato spotted wilt
- Varnish spot
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See also, pests of other regions: Central
Coast and Desert. Names link
to more information on identification and management.
Click on photos to enlarge
Beet armyworm larvae
Identification tip: Newly hatched larvae
are small, green worms that often feed in groups. |
Armyworm
Identification tip: Larvae are variable in color but are usually dark green or gray, with three thick stripes running down each side.
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Looper damage
Identification tip: Larvae feed primarily on
the undersides of lower leaves, skeletonizing them
and contaminating them with frass. |
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Corn earworm
Identification tip: As larvae mature they develop distinct stripes, but the overall color is variable.
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Green peach aphids
Identification tip: Green peach aphids are dark
green to yellow and have no waxy covering.
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Botrytis rot damage
Identification tip: Damaged heads show gray spores on
wilted, outermost leaves.
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Tip burn (warm weather)
Identification tip: Leaf tips turn brown. |
Big vein damage
Identification tip: Veins in leaves become enlarged
and clear; easily seen if leaf is examined with the light source
behind it. Enlarged veins cause the rest of the leaf to be
ruffled and malformed.
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Lettuce dieback
Identification tip: Outermost leaves are extensively
yellowed. The younger, inner leaves often remain dark green
in color, but can be rough and leathery in texture. |
Powdery mildew damage
Identification tip: Appears as a white, powdery
growth on both upper and lower sides of lettuce leaves.
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Powdery mildew damage
Identification tip: Severe powdery mildew infection.
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Lettuce drop
Identification tip: Older leaves wilt; eventually
the entire plant wilts and collapses, making it unharvestable.
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Anthracnose damage
Identification tip: Small, water-soaked spots (less
than 3 mm) on outer leaves eventually enlarge, turn yellow,
and become irregular and angular in shape.
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Corky root damage
Identification tip: Roots show reduced feeder
roots and a rough, pitted taproot.
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Tomato spotted wilt
Identification tip: Iceberg lettuce develops necrotic
lesions on leaves.
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Varnish spot (Pseudomonas
cichorii) damaged head
Identification tip: Leaves exhibit dark brown spots
that are firm and shiny. |
Lettuce chlorosis
Identification tip: Symptoms of lettuce chlorosis
and lettuce infectious yellows are virtually identical. Leaves
exhibit severe yellowing, rolling, brittleness, and vein-clearing. |
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