Diseases of Poinsettia
(Euphorbia pulcherrima Willd. ex Klotzsch)

G. W. Simone, primary collator (last update 11/08/00)

BACTERIAL DISEASES

Bacterial leaf spot

Curtobacterium flaccumfaciens (Hedges 1922) Collins and
    Jones 1984

= Corynebacterium flaccumfaciens pv. poinsettiae
    (Starr & Pirone 1942) Dye & Kemp 1977

Pseudomonas cichorii (Swingle 1925) Stapp 1928

Ps. marginalis (Brown 1918) Stevens 1925

Ps. syringae subsp. syringae van Hall 1902

Xanthomonas campestris pv. poinsettiaecola (Patel et al.
    1951) Dye 1978

Bacterial stem rot

Erwinia carotovora subsp. carotovora (Jones 1901) Bergey
    et al. 1923

Erwinia chrysanthemi Burkholder et al. 1953

Crown gall

Agrobacterium tumefaciens (Smith and Townsend 1907) Conn 1942

Greasy center

Pseudomonas viridiflava (Burkholder 1930) Dowson 1939

FUNGAL DISEASES

Anthracnose

Colletotrichum capsici (Syd.) E.J. Butler & Bisby

Colletotrichum dematium (Pers.) Grove

Glomerella cingulata (Stoneman) Spauld. & H. Schrenk

    C. gloeosporioides (Penz.) Penz. & Sacc. in Penz.
    [anamorph]

Aerial blight

Ceratobasidium ramicola Tu, D.A. Roberts & Kimbrough

    Rhizoctonia ramicola G.F. Weber & D.A. Roberts
    [anamorph]

Basal stem and crown rot

Sclerotinia sclerotiorum (Lib.) deBary

Basal stem and root rot

Ceratocystis sp.

    Thielaviopsis basicola (Berk. & Broom) Ferraris
        [anamorph]

    Chalara elegans Nag Raj & Kendrick [synanamorph]

Black rot

Botryodiplodia sp.

Bract, flower and leaf blight

Phytophthora drechsleri Tucker

Bract spot

Corynespora cassiicola (Berk. & M.A. Curtis) C.T. Wei

Crown and stem rot

Fusarium oxysporum Schlechtend.:Fr.

Nectria haematococca Berk. & Broome

    Fusarium solani (Mart.) Sacc. [anamorph]

Cutting rot

Cylindrocladium scoparium Morgan

Dieback

Lasiodiplodia theobromae (Pat.) Griffon & Maubl.

=Botryosphaeria theobromae Pat.

Gray mold

Botryotinia ricini (Godfrey) Whetzel

    Amphobotrys ricini (Buchwald) Hennebert [anamorph]

=Botrytis ricini

Botryotinia fuckeliana (deBary) Whetzel

    Botrytis cinerea Pers.:Fr. [anamorph]

Leaf necrosis

Cladosporium sp.

Macrophoma sp.

Leaf spot

Alternaria euphorbiicola E. Simmons & Engelhard

Ascochyta sp.

Cercospora pulcherrimae Tharp

Curvularia sp.

Drechslera sp.

Myrothecium roridum Tode:Fr.

Phyllosticta sp.

Syspastospora parasitica (Tul.) P. Cannon & D. Hawksworth

= Melanospora parasitica (Tul.) Tul. & C. Tul.

Stemphylium sp.

Mushroom root rot

Armillaria tabescens (Scop.) Dennis, Orton & Hora

Powdery mildew

Oidium sp.

Erysiphe sp.

Microsphaera euphorbiae Berk. & M.A. Curtis

Root rot

Phytophthora nicotianae Breda de Haan

= P. nicotianae var. parasitica (Dastur) G.M. Waterhouse

Pythium aphanidermatum (Edson) Fitsp.

P. debaryanum Auct. non R. Hesse

P. myriotylum Drechs.

P. perniciosum Serbinow

P. splendens H. Braun

P. ultimum Trow

Root and stem rot

Thanatephorus cucumeris (A.B. Frank) Donk

    Rhizoctonia solani Kühn [anamorph]

Rust

Puccinia sp.

Uromyces euphorbiae Cooke & Peck in Peck

= U. proeminens Pass. In Rabenh. var. poinsettiae
    (Tranzschel) Arth.

Scab

Sphaceloma poinsettiae Jenk. & Ruehle

Stem gall

Nectriella pironii Alfieri & Samuels

    Kutilakesa pironii Alfieri [anamorph]

Stem rot

Botryosphaeria ribis Gross. & Duggar

Diplodia sp.

Leptothyrium sp.

Phoma sp.

Phomopsis sp.

NEMATODES, PARASITIC

Root knot nematode

Meloidogyne spp.

VIRAL and VIROID DISEASES

Mosaic

genus Bigeminivirus, Euphorbia mosaic virus (EuMV)

Poinsettia mosaic virus (possible tymovirus) (PnMV)

(symptomless)

Poinsettia (?) alphacryptovirus (PnCV)

MISCELLANEOUS DISEASES and DISORDERS

Bleaching necrosis

Air pollutant injury from either chlorides (> 0.5 ppm), nitrogen dioxide (> 2-3 ppm) or sulfur dioxide (> 0.5 ppm)

Bract necrosis

Physiological disorder favored by high humidity, heavy watering and high (ammoniacal) fertility rates in the last 4 weeks of production

Chlorosis

Nitrogen deficiency producing a general foliar yellowing

Molybdenum deficiency affecting mature young leaves and
    producing upward leaf roll

Sulfur deficiency causing young leaf yellowing

Zinc deficiency producing general yellowing and stunting of
    new leaves

Cyathia drop

Response to low light conditions, dryness and/or high temperatures at the end of the production cycle

Dropping (epinasty)

Ethylene toxicity (< 1 ppm) or low temperature chilling

Edema

Physiological

Interveinal chlorosis

Magnesium deficiency, initiating on older leaves

Manganese deficiency, initiating on young mature leaves

Ammonium toxicity produces V-shaped chlorotic bands
    starting at the leaf tip and accompanied by downward leaf
    cupping

Latex eruption

High internal turgor pressure associated with certain cultivars, high humidity, high moisture availability, low temperatures and/or mechanical abrasion

Leaf glazing (bronzing)

Peroxyacetyl nitrate (PAN) injury to the lower epidermis

(> 0.2 ppm)

Marginal necrosis

Potassium deficiency

Fluoride toxicity on tips and margins of young leaves and bracts
    (0.4 ppm in water)

Lithium toxicity on older leaves (2 ppm)

Stem splitting

Physiological expression of flower initiation

Stippling

Ozone injury (> 4 ppm)

Terminal shoot necrosis

Excessive soluble salts (> 800 EC X 10²)

White bract

Chilling injury occurring between 0-10°C (32-50°F)