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Diseases of Lettuce (Lactuca sativa L.)

K. V. Subbarao, R. M. Davis, R. L. Gilbertson, and R. N. Raid, primary collators (last update: 7/1/2017)

BACTERIAL DISEASES

Bacterial leaf spot (BLS)

Xanthomonas campestris pv. vitians (Brown) Dye

Bacterial soft rot

Pectobacterium carotovorum subsp. carotovorum (Jones) Hauben et al.

       (syn. Erwinia carotovora subsp. carotovora (Jones) Bergey et al.)

Bacterial soft rot (Postharvest)

Pectobacterium carotovorum subsp. carotovorum (Jones) Hauben et al.

       (syn. Erwinia carotovora subsp. carotovora (Jones) Bergey et al.)

Pseudomonas marginalis pv. marginalis

Corky root

Rhizorhapis suberifaciens et al.

Marginal leaf blight

Pseudomonas marginalis pv. marginalis(Brown) Stevens

Varnish spot

Pseudomonas cichorii (Swingle) Stapp

FUNGAL AND OOMYCETE DISEASES

Alternaria leaf spot

Alternaria sonchi Davis

Anthracnose

Microdochium panattonianum (Berl.) Sutton, Galea & Price

       (syn. Marssonina panattoniana (Berl.) Magnus)

Black rot

Ceratocystis fimbriata Ellis & Halst.

Black root rot

Thielaviopsis basicola (Berk. & Broome) Ferraris

       (syn. Chalara elegans Nag Raj & W. B. Kendr.)

Bottom rot

Rhizoctonia solani J. G. Kühn

       (syn. Thanatephorus cucumeris (A. B. Frank) Donk)

Cercospora leaf spot

Cercospora apii Fresen.

C. lactucae-sativae Sawada

       (syn. C. longissima Cugini ex Trav., illeg. hom.)

Damping-off, Pythium

Pythium dissotocum Drechsler

P. irregulare Buisman

P. myriotylum Drechsler

P. sylvaticum W. A. Campb. & F. F. Hendrix

P. ultimum Trow

P. uncinulatum Plaats-Niterink & I. Blok

P. violae Chesters & Hickman

Damping-off, Rhizoctonia

Rhizoctonia solani J. G. Kühn

Downy mildew

Bremia lactucae Regel

Plasmopara lactucae-radicis Stangh. & Gilb.

Drop (Sclerotinia rot)

Sclerotinia minor Jaggar

S. sclerotiorum (Lib.) de Bary

Fusarium wilt (Fusarium root rot)

Fusarium oxysporumf. sp. lactucae Matuo & Motohashi

Gray mold (Pre- and postharvest)

Botrytis cinerea Pers.:Fr.

       (syn. Botryotinia fuckeliana (de Bary) Whetzel)

Phoma leaf spot and basal rot

Boeremia exigua (Desm.) Aveskamp, Gruyter & Verkley

       (syn. Phoma exigua Desm.)

P. tropica R. Schneid. & Boerema

Phytophthora stem and root rot

Phytophthora cryptogea Pethybr. & Laff.

P. drechsleri Tucker

P. lactucae Bertier, H. Brouwer & DeCock

P. pseudolactucae M. Z. Rahman et al.

Powdery mildew

Golovinomyces cichoracearum (DC.) V. P. Heluta

       (syn. Erysiphe cichoracearum DC.)

Pythium wilt and leaf blight

Pythium aphanidermatum (Edson) Fitzp.

P. megalacanthum de Bary

P. polymastum Dreschsler

P. spinosum Sawada

P. tracheiphilum Matta

P. ultimum Trow

P. uncinulatum Plaats-Niterink & I. Blok

Rust

Puccinia dioicae Magnus

       (syn. P. extensicola Plowr. var. hieraciata (Schwein.) Arthur)

Septoria leaf spot

Septoria birgitae Bedlan

S. lactucae Pass.

Southern blight

Athelia rolfsii (Curzi) C. C. Tu & Kimbr.

       (syn. Sclerotium rolfsii Sacc.)

Stemphylium leaf spot

Stemphylium botryosum f. sp. lactucum Padhi & Snyder

       (syn. Pleospora tarda E. G. Simmons)

S. solani G. F. Weber

Texas root rot (Phymatotrichum root rot, Cotton root rot)

Phymatotrichopsis omnivora (Shear) Hennebert

       (syn. Phymatotrichum omnivorum (Shear) Duggar)

Verticillium wilt

Verticillium dahliae Kleb.

V. isaacii Inderb. et al.

V. klebahnii Inderb. et al.

NEMATODES, PARASITIC

False root-knot

Nacobbus aberrans (Thorne) Thorne & Allen

Lesion

Pratylenchus penetrans (Cobb) Filipjev & Schuurmans Stekhoven

Needle

Longidorus africanus Merny

Root-knot

Meloidogyne arenaria (Neal) Chitwood

M. hapla Chitwood

M. incognita (Kofoid & White) Chitwood

M. javanica (Treub) Chitwood

Spiral

Rotylenchus robustus (de Man) Filipjev

Stunt

Tylenchorhynchus clarus Allen

NONINFECTIOUS DISEASES, DISORDERS, AND DAMAGE

Ammonium toxicity

Physiological; excess ammonium levels during cool soil temperatures (<10–15^○C)

Bird damage

Brown-headed cowbird (Molothrus ater Boddaert)

Great-tailed grackle (Quiscalus mexicanus Gmelin)

Horned lark (Eremophila alpestris L.)

House finch (Carpodacus mexicanus Statius Müller)

Red-winged blackbird (Agelaius phoeniceus L.)

White-crowned sparrow (Zonotrichia leucophrys J. R. Forster)

Bolting

Physiological; prolonged high temperatures (35/25^○C, day/night)

Brown stain

Physiological; excess carbon dioxide; occurs postharvest

Cold injury

Environmental; low temperatures (–2^○ to 1^○C)

Hail injury

Environmental; hail storm during the early seedling stage or just before harvest

Heat injury

Environmental; high temperatures (>32^○C) during seedling stages

Herbicide injury

Chemical; various classes of herbicides used in excess or under adverse environmental conditions

Lightning injury

Environmental; lightning strike at any crop stage

Pink rib

Physiological; rapid growth and/or higher than optimal postharvest storage temperatures (1.1–2.2^○C); occurs postharvest

Rib discoloration

Physiological; high temperatures after the onset of heading

Russet spotting

Physiological; excess ethylene; occurs postharvest

Tipburn

Physiological; localized calcium deficiency and insufficient water uptake, high light intensity, warm temperatures, and high fertilization rates

Wind injury

Environmental; wind whipping followed by girdling of seedlings or soil particles in the heads at harvest

PARASITIC HIGHER PLANT

Broomrape

Orobanche cernua Loefl.

O. crenata Forssk.

O. minor Sm.

O. palaestina Reut.

Phelipanche aegyptiaca (Pers.) Pomel

       (syn. O. aegyptiaca Pers.)

P. ramosa (L.) Pomel

       (syn. O. ramosa L.)

PHYTOPLASMA DISEASES

Australian lettuce phyllody

Faba bean phyllody phytoplasma group

Lettuce phyllody

Pigeon pea witches’-broom phytoplasma group

Lettuce yellows (Aster yellows)

 ‘Candidatus Phytoplasma asteri’

       (syn. Aster yellows phytoplasma)

VIRUS DISEASES

Alfalfa mosaic

Genus Alfamovirus; Alfalfa mosaic virus (AMV)

Beet western yellows

Genus Polerovirus; Beet western yellows virus (BWYV)

Beet yellow stunt

Genus Closterovirus; Beet yellow stunt virus (BYSV)

Bidens mottle

Genus Potyvirus; Bidens mottle virus (BiMoV)

Broad bean wilt

Genus Fabavirus; Broad bean wilt virus (BBWV)

Cucumber mosaic

Genus Cucumovirus; Cucumber mosaic virus (CMV)

Dandelion yellow mosaic

Genus Sequivirus; Dandelion yellow mosaic virus (DaYMV)

Impatiens necrotic spot

Genus Tospovirus; Impatiens necrotic spot virus (INSV)

Lettuce big vein

Genus Ophiovirus; Mirafiori lettuce big-vein virus (MLBVV)

Genus Varicosavirus; Lettuce big-vein associated virus (LBVaV)

Lettuce chlorosis

Genus Crinivirus; Lettuce chlorosis virus (LCV)

Lettuce dieback

Genus Tombusvirus; Tomato bushy stunt virus (TBSV), Moroccan pepper virus (MPV)

Lettuce mosaic

Genus Potyvirus; Lettuce mosaic virus (LMV)

Lettuce mottle

Genus Sequivirus; Lettuce mottle virus (LeMoV)

Lettuce necrotic yellows

Genus Cytorhabdovirus; Lettuce necrotic yellows virus (LNYV)

Sonchus yellow net

Genus Nucleorhabdovirus; Sonchus yellow net virus (SYNV)

Sowthistle yellow vein

Genus Nucleorhabdovirus; Sowthistle yellow vein virus (SYVV)

Tobacco rattle

Genus Tobravirus; Tobacco rattle virus (TRV)

Tobacco ringspot

Genus Nepovirus; Tobacco ringspot virus (TRSV)

Tobacco streak

Genus Ilarvirus; Tobacco streak virus (TSV)

Tomato spotted wilt

Genus Tospovirus; Tomato spotted wilt virus (TSWV), Groundnut ringspot virus (GRSV), Impatiens necrotic spot virus (INSV), Tomato chlorotic spot virus (TCSV)

Turnip mosaic

Genus Potyvirus; Turnip mosaic virus (TuMV)