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Lettuce
> Year-Round IPM Program > Heading
to Harvest > Pest
Damage (Central Coast)
Lettuce
Pests and their Damage—Heading to Harvest (Central Coast)
On this page
- Botrytis crown rot
- Corky root
- Tip burn
- Downy mildew
- Lettuce dieback
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- Powdery mildew
- Lettuce chlorosis
- Tomato spotted wilt
- Varnish spot
- Leafminer
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- Green peach aphids
- Lettuce aphid
- Loopers
- Thrips
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See also, pests of other regions: Central
Valley and Desert. Names link
to more information on identification and management.
Click on photos to enlarge
Botrytis rot damage
Identification tip: Damaged heads show gray spores on
wilted, outermost leaves.
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Corky root damage
Identification tip: Roots show reduced feeder roots
and a rough, pitted taproot.
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Tip burn (warm weather)
Identification tip: Leaf tips turn brown.
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Downy mildew damage
Identification tip: Light green to yellow angular
spots develop on the upper surface of the leaf. |
Downy mildew damage
Identification tip: Underneath the leaf, immediately below these angular
spots, white fluffy fungal masses grow. With time lesions turn brown and dry
up. |
Powdery mildew
Identification tip: Appears as a white, powdery
growth on both upper and lower sides of lettuce leaves. |
Powdery mildew
Identification tip: Severe powdery mildew infection.
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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.
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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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Tomato spotted wilt
Identification tip: Iceberg lettuce develops necrotic
lesions on leaves. |
Varnish spot (Pseudomonas
cichorii) damaged head
Identification tip: Leaves exhibit dark brown spots
that are firm and shiny. |
Leafminers (Liriomyza spp.)
damage
Identification tip: A larva mines between upper
and lower leaf surfaces, creating winding tunnels that
widen as the larva grows. |
Green peach aphids
Identification tip: Green peach aphids are dark
green to yellow and have no waxy covering.
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Lettuce aphid
Identification tip: The adult has black markings
on leg joints and antennae. They may have dark bands across
their abdomen. |
Looper damage
Identification tip: Larvae feed primarily on the
undersides of lower leaves, skeletonizing them and contaminating
them with frass. |
Western flower thrips damage
Identification tip: Leaves have feeding punctures
and small, black, fecal deposits. |
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