Lettuce: Anthracnose Categories: Lettuce Lettuce Diseases Vegetables Last review date: 2026-07-30 09:35 Lettuce anthracnose magnified Photo by: R.S. Byther Biology Anthracnose of lettuce is a fungal disease favored by cool, wet weather. The disease is also known as shothole because of the characteristic symptoms. Lower leaves develop small, water-soaked spots which quickly darken and enlarge. […]
Lettuce: Aster yellows Categories: Lettuce Lettuce Diseases Vegetables Last review date: 2026-07-31 11:59 Lettuce plant displaying symptoms of infection with a phytoplasma. Photo by: William M. Brown Jr., Bugwood.org Biology Aster yellows is caused by a phytoplasma which is a microorganism found in the phloem tissue of a plant. The phytoplasma is spread by leafhoppers […]
Lettuce: Beet western yellows virus Categories: Lettuce Lettuce Diseases Vegetables Last review date: 2026-07-31 01:57 Oldest leaves turn yellow prematurely, typically beginning at the margins and progressing in; veins and midribs tend to remain green. Photo by: Melodie Putnam, 1992, PNW Pest Management Handbooks Biology Beet Western Yellows is a virus which affects many garden […]
Lettuce: Bottom rot Categories: Lettuce Lettuce Diseases Vegetables Last review date: 2026-07-31 12:47 Lettuce bottom rot Photo by: R.S. Byther Biology Bottom rot of lettuce is caused by a soil-borne fungus that is common in wet soils. Head lettuces, particularly the ‘Big Boston’ types, are attacked as they near maturity. The stems and midrib/midvein of […]
Lettuce: Damping-off Categories: Lettuce Lettuce Diseases Vegetables Last review date: 2026-07-31 01:46 Damping-off of cucumber seedlings Photo by: R.S. Byther Biology Damping-off is caused by fungi that remain in the soil for long periods of time. Seeds decay without germinating. Seedlings may be infected and fail to emerge from the soil. Emerged seedlings are also […]
Lettuce: Downy mildew Categories: Lettuce Lettuce Diseases Vegetables Last review date: 2026-07-31 01:53 Lettuce leaf infected with downy mildew fungus Photo by: R.S. Byther Biology Lettuce downy mildew is caused by a fungus which survives the winter on wild hosts and weeds. Light green or yellowish areas on the upper leaf surface are in places […]
Lettuce: Lettuce big vein virus Categories: Lettuce Lettuce Diseases Vegetables Last review date: 2026-07-31 02:02 Lettuce big vein virus symptoms Photo by: R.S. Byther Biology Lettuce Big Vein Virus is transmitted by a fungus which inhabits the roots. Virus infection causes tissues next to veins to become clear, resulting in an enlarged appearance of the […]
Lettuce: Aphids Categories: Lettuce Lettuce Insects Vegetables Last review date: 2026-07-31 11:11 Aphid colony on leaf Photo by: A.L. Antonelli Biology Aphids are small, soft-bodied, pear-shaped insects. They may vary in color from yellow to green to dark. Aphids typically feed in colonies on the leaves, often preferring the newer growth. Infested leaves turn yellow […]
Lettuce: Slugs Categories: Lettuce Lettuce Insects Vegetables Last review date: 2026-07-31 02:08 Slug damage and slime Photo by: R.S. Byther Biology Slugs are common garden pests in western Washington. They resemble snails, but lack shells. They may vary from as little as 1⁄4″ up to several inches in length, depending on age and species. Slugs […]