Diseases of Pear (Pyrus communis L.)

Robert A. Spotts, primary collator (last update 3/13/93)

BACTERIAL DISEASES

Crown gall

Agrobacterium tumefaciens (Smith & Townsend) Conn

Fire blight

Erwinia amylovora (Burrill) Winslow et al.

Pseudomonas blossom blast and canker

Pseudomonas syringae pv. syringae van Hall

FUNGAL DISEASES

Alternaria fruit rot

Alternaria spp.

Anthracnose canker and bull's-eye rot

Pezicula malicorticus (H. Jacks) Nannf.

(anamorph: Cryptosporiopsis curvispora (Peck) Gremmen in
    Boerema & Gremmen)

Armillaria root rot (shoestring root rot)

Armillaria mellea (Vahl:Fr.) P. Kumm.

(anamorph: Rhizomorpha subcorticalis Pers.)

Bitter rot

Glomerella cingulata (Stoneman) Spauld. & Schrenk

(anamorph: Colletotrichum gloeosporioides (Penz.) Penz. &
    Sacc. in Penz.

Black rot, leaf spot and canker

Botryosphaeria obtusa (Schwein.) Shoemaker

(anamorph: Sphaeropsis malorum Berk.)

Black spot (of Japanese pear)*

Alternaria alternata (Fr.:Fr.) Keissl.

Blister canker

Helminthosporium papulosum Berg.

Blister disease*

Coniothecium chromatosporum Corda

Blue mold rot

Penicillium spp.

P. expansum Link

Botrytis spur and blossom blight

Botrytis cinerea Pers.:Fr.

(teleomorph: Botryotinia fuckeliana (de Bary) Whetzel)

Brown rot

Monilinia fructicola (Wint.) Honey

M. laxa (Aderh. & Ruhl.) Honey

Cladosporium fruit rot

Cladosporium herbarum (Pers.:Fr.) Link

(teleomorph: Mycosphaerella tassiana (De Not.) Johans.)

Clitocybe root rot (mushroom root rot)

Armillaria tabescens (Scop.) Dennis et al.

= Clitocybe tabescens (Scop.) Bres.

Coprinus rot

Coprinus psychromorbidus Redhead & Traquair

Dematophora root rot (Rosellinia root rot)

Rosellinia necatrix Prill.

(anamorph: Dematophora necatrix R. Hartig)

Diplodia canker

Botryosphaeria stevensii Shoemaker

= Physalospora malorum Shear et al.

(anamorph: Diplodia mutila (Fr.:Fr.) Mont.)

Elsinoe leaf and fruit spot

Elsinoe piri (Woronichin) Jenk.

(anamorph: Sphaceloma pirinum Jenk.)

European canker

Nectria galligena Bres. in Strass.

(anamorph: Cylindrocarpon heteronemum (Berk. &
    Broome) Wollenweb.)

Fabraea leaf and fruit spot

Diplocarponmespili (Sorauer) Sutton

= Fabraea maculata Atk.

(anamorph: Entomosporium mespili (DC.) Sacc.)

Fly speck

Schizothyrium pomi (Mont.:Fr.) Arx

(anamorph: Zygophiala jamaicensis E. Mason)

Gibberella canker

Gibberella baccata (Wallr.) Sacc.

(anamorph: Fusarium lateritium Nees:Fr.)

Gray mold rot

Botrytis cinerea Pers.:Fr.

Late leaf spot

Cercospora minima Tracy & Earle

Mucor fruit rot

Mucor spp.

M. piriformis E. Fischer

Mycosphaerella leaf spot (ashy leaf spot and fruit spot)

Mycosphaerella pyri (Auersw.) Boerema

= M. sentina (Fr.:Fr.) Schrot.

(anamorph: Septoria pyricola (Desmaz.) Desmaz.)

Nectria twig blight (coral spot)

Nectria cinnabarina (Tode) Fr.

(anamorph: Tubercularia vulgaris Tode)

Pear scab

Venturia pirina Aderh.

(anamorph: Fusicladium pyrorum (Lib.) Fuckel)

Perennial canker

Neofabrae perennans Kienholz

(anamorph: Cryptosporiopsis perennans (Zeller & Childs)
    Wollenweb.)

Phyllosticta leaf spot

Phyllosticta sp.

Phytophthora crown and root rot (sprinkler rot)

Phytophthora cactorum (Lebert & Cohn) J. Schrot.

Pink mold rot

Trichothecium roseum (Pers.:Fr.) Link

= Cephalothecium roseum Corda

Powdery mildew

Podosphaera leucotricha (Ellis & Everh.) E.S. Salmon

Pythium dieback

Pythium spp.

Rhizopus rot

Rhizopus stolonifer (Ehrenb.:Fr.)Vuill.

Rust, American hawthorne

Gymnosporangium globosum (Farl.) Farl.

Rust, Kern's pear

Gymnosporangium kernianum Bethel

Rust, Pacific Coast pear

Gymnosporangium libocedri (C. Henn.) F. Kern

Rust, pear trellis (European pear rust)

Gymnosporangium fuscum R. Hedw. in DC.

Rust, Rocky Mountain pear

Gymnosporangium nelsonii Arth.

Side rot

Phialophora malorum (M.N. Kidd & A. Beaumont) McColloch

Silver leaf

Chondrostereum pupureum (Pers.:Fr.) Pouzar

Sooty blotch

Gloeodes pomigena (Schwein.) Colby

Thread blight (Hypochnus leaf blight)

Corticiumstevensii Burt

= Pellicularia koleroga Cooke

= Hypochnus ochroleucus Noack

Valsa canker

Valsa ceratosperma (Tode:Fr.) Maire

(anamorph: Cytospora sacculus (Schwein.) Gvritischvili)

Wood rot

Trametes versicolor (L.:Fr.) Pilat and various basidiomycetes

Xylaria root rot

Xylaria spp.

MISCELLANEOUS DISEASES OR DISORDERS

Alfalfa greening (green stain)

Unknown

Bitter pit

Localized calcium deficiency

Black end

Water imbalance

Black speck (skin speckling)

Associated with low oxygen in storage

Blossom blast

Boron deficiency

Brown core

High CO2

Core breakdown (Bartlett)

Senescence

Core spot

Associated with calcium deficiency

Green stain

Unknown

Internal bark necrosis

Unknown

Mealy core (d`Anjou)

Senescence

Pink end (Bartlett)

Preharvest low temperature

Rosette

Unknown

Scald

Senescence

NEMATODES, PARASITIC

Dagger, American

Xiphinema americanum Cobb.

Dagger

X. riveri Dalmasso

X. vuittenezi Luc et al.

Lesion

Pratylenchus spp.

P. penetrans (Cobb) Filipjev & Schuurmans-Stekhoven

Pin

Paratylenchus spp.

Root-knot

Meloidogyne spp.

VIRUSLIKE DISEASES

Flemish beauty corky pit

Virus suspected

Pear blister canker

Virus suspected

Pear decline

MLO

Pear freckle pit

Virus suspected

Pear red mottle

Virus suspected

Pear ring pattern mosaic

Virus suspected

Pear rough bark

Virus suspected

Pear stony pit

Virus suspected

Pear vein yellows

Virus suspected

Quince bark necrosis

Virus suspected

Quince sooty ring spot

Virus suspected

Quince stunt

Virus suspected

Quince yellow blotch

Virus suspected

*Not known to occur naturally on pear in the United States.