Lettuce

Visual Description:

Plants rapidly develop a central flowering stalk that elongates above the main leaf rosette. Leaves become more pointed, tough, and increasingly bitter. The stem stretches upward, often reaching 2-3 feet tall. Once bolting begins, the plant focuses energy on flower and seed production rather than leaf development. The entire plant becomes unusable as the bitterness increases.

Visual Description:

The edges of inner, younger leaves turn brown and appear scorched or burned. The affected tissue becomes dry and papery. In head lettuce, the damage may not be visible until the head is cut open. The condition often develops rapidly during periods of fast growth. While the rest of the leaf remains green, the brown edges make the lettuce less marketable.

Visual Description:

Rot begins on leaves in contact with the soil, appearing as brown, water-soaked spots that quickly enlarge. The affected tissue becomes mushy and may develop a reddish-brown color. The disease can progress rapidly up the plant, especially in wet conditions. In severe cases, the entire head may collapse and rot. A thin layer of white fungal growth may be visible in humid conditions.

Visual Description:

Yellow to light green spots appear on upper leaf surfaces, while the corresponding lower surface shows white to gray fuzzy growth. The spots may merge, causing entire leaves to yellow and die. The disease typically starts on older, outer leaves and moves inward. In humid conditions, the fuzzy growth is most visible in the morning.

Visual Description:

Small (1/8 inch) green, white, or gray insects cluster on leaf undersides and in growing points. Leaves may curl or become distorted. Sticky honeydew secreted by aphids can lead to black sooty mold growth. Heavy infestations cause yellowing and stunting. The presence of aphids can make lettuce unmarketable.

Visual Description:

Leaves show mottled patterns of light and dark green, often with distorted or puckered areas. Growth is stunted, and heads may not form properly. Veins may appear cleared or yellowed. The virus can cause internal browning in head lettuce. Infected plants are usually stunted and produce unmarketable heads.