Diseases of Lettuce
(Lactuca sativa L.)

Bacterial leaf spot and head rot: Xanthomonas campestris pv. vitians (Brown) Dye
Bacterial soft rot: Erwinia carotovora (Jones) Bergey et al.; Pseudomonas marginalis (Brown) Stevens
Corky root: Rhizomonas spp.; R. suberifaciens van Bruggen et al.
Varnish spot: Pseudomonas cichorii (Swingle) Stapp

Alternaria leaf spot: Alternaria sonchi J.J. Davis in J.A. Elliott
Anthracnose: Microdochium panattonianum (Berl.) Sutton et al. in Galea
et al.; = Marssonina panattoniana (Berl.) Magnus
Bottom rot: Rhizoctonia solani Kühn; (teleomorph: Thanatephorus cucumeris (A.B. Frank) Donk)
Cercospora leaf spot: Cercospora longissima Sacc.
Damping-off, Pythium: Pythium spp.; P. ultimum Trow
Damping-off, Rhizoctonia: Rhizoctonia solani Kühn
Downy mildew: Bremia lactucae Regel; Plasmopara lactucae-radicis Stanghellini & Gilbertson
Drop (Sclerotinia rot): Sclerotinia sclerotiorum (Lib.) de Bary; S. minor Jaggar
Gray mold: Botrytis cinerea Pers.:Fr.; (teleomorph: Botryotinia fuckeliana (de Bary) Whetzel)
Phymatotrichum root rot (cotton root rot): Phymatotrichopsis omnivora (Duggar) Hennebert; = Phymatotrichum omnivorum Duggar
Powdery mildew: Erysiphe cichoracearum DC.
Rust: Puccinia dioicae Magnus; = P. extensicola Plowr. var. hieraciata (Schwein.) Arthur
Septoria leaf spot: Septoria lactucae Pass.
Southern blight: Sclerotium rolfsii Sacc.; (teleomorph: Athelia rolfsii (Curzi) Tu & Kimbrough)
Stemphylium leaf spot: Stemphylium botryosumWallr.; (teleomorph: Pleospora tarda E. Simmons)
Wilt and leaf blight: Pythium tracheiphilum Matta

(Also mycoplasmalike organism [MLO])

Big vein: Lettuce big vein virus
Calico: Alfalfa mosaic virus; Tobacco ringspot virus
Internal rib necrosis: Lettuce mosaic virus
Mosaic: Lettuce mosaic virus; Biden mosaic virus; Cucumber mosaic virus; Turnip mosaic virus
Necrotic yellows: Lettuce necrotic yellows virus
Ring necrosis: Presumed viral agent (not identified)
Rusty brown discoloration: Accentuated by lettuce mosaic virus
Speckles: Lettuce speckles virus and beet western yellows virus
Stunt: Beet yellow stunt virus
Virescence: Aster yellows MLO; Beet leafhopper-transmitted virescence MLO
Wilt: Broadbean wilt virus; Tomato spotted wilt virus
Yellow spot: Tobacco rattlevirus
Yellows: Beet western yellows virus
Other: Sow thistle yellow vein virus

**Calcium

Diseases of Lettuce(Lactuca sativa L.)