Check for stand uniformity and wilted
plants and inspect plants for pests and pest damage.
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.
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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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Cutworms
Identification tip: Larvae frequently roll into
a C-shape when disturbed. |
Corn earworm damage
Identification tip: As larvae mature they develop distinct stripes, but the overall color is variable.
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Looper damage
Identification tip: Larvae feed primarily on the
undersides of lower leaves, skeletonizing them and contaminating
them with frass. |
Saltmarsh caterpillar
Identification tip: Early instars are various
shades of yellow-brown with long, dark hairs. |
Silverleaf whiteflies
Identification tip: Adults are tiny 0.06 inch (1.5 mm) long, yellowish insects
with white wings. |
Corky root damage
Identification tip: Roots show reduced feeder
roots and a rough, pitted taproot.
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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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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. |
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
drop
Identification tip: Older leaves wilt; eventually the
entire plant wilts and collapses, making it unharvestable.
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Lettuce mosaic
Identification tip: Symptoms of lettuce mosaic vary greatly based on the lettuce variety and the stage of lettuce at time of infection. One symptom is the development of a mottling pattern on leaves.
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Downy mildew damage
Identification tip: Light green to yellow angular spots
develop on the upper surface of the leaf.
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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.
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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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Bottom rot (Rhizoctonia diseases)
Identification tip: Brown sunken lesions form on
midribs in contact with soil. Lesions may expand to rot
lower leaves.
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Ammonium toxicity
Identification tip: Discolored vascular tissue caused by ammonium toxicity. |
Powdery mildew damage
Identification tip: Appears as a white, powdery growth
on both upper and lower sides of lettuce leaves. |
Powdery mildew damage
Identification tip: Severe powdery mildew infection
on iceberg lettuce. |
Lettuce chlorosis
Identification tip: Symptoms of lettuce chlorosis
and lettuce infectious yellows are virtually identical. Leaves
exhibit severe yellowing, rolling, brittleness, and vein-clearing. |
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. |
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