The following is a list of diseases of pears (Pyrus communis).
Bacterial diseases Bacterial diseasesCrown gallAgrobacterium tumefaciensFire blight Erwinia amylovoraPseudomonas blossom blast and canker Pseudomonas syringae pv. syringaePear declinePhytoplasma
Fungal diseases Fungal diseasesAlternaria fruit rot Alternaria spp. Anthracnose canker and bull's-eye rot Pezicula malicorticus Cryptosporiopsis curvispora [anamorph] Armillaria root rot (shoestring root rot) Armillaria mellea Rhizomorpha subcorticalis [anamorph]Bitter rot Glomerella cingulata Colletotrichum gloeosporioides [anamorph]Black rot, leaf spot and canker Botryosphaeria obtusa Sphaeropsis malorum [anamorph]Black spot (of Japanese pear)Alternaria alternataBlister canker Helminthosporium papulosum Blister diseaseConiothecium chomatosporumBlue mold rot Penicillium spp. Penicillium expansumBotrytis spur and blossom blight Botrytis cinerea Botryotinia fuckeliana [teleomorph] Brown rot Monilinia fructicola Monilinia laxaCladosporium fruit rot Cladosporium herbarum Mycosphaerella tassiana [teleomorph] Clitocybe root rot (mushroom root rot) Armillaria tabescens Clitocybe tabescensCoprinus rot Coprinopsis psychromorbidaDematophora root rot (Rosellinia root rot) Rosellinia necatrix Dematophora necatrix [anamorph]Diplodia canker Botryosphaeria stevensii Physalospora malorum Diplodia mutila [anamorph]Elsinoe leaf and fruit spot Elsinoe piri Sphaceloma pirinum [anamorph]European canker Nectria galligena Cylindrocarpon heteronemum [anamorph]Fabraea leaf and fruit spot Diplocarpon mespili Fabraea maculata Entomosporium mespili [anamorph]Fly speck Schizothyrium pomi Zygophiala jamaicensis [anamorph]Gibberella canker Gibberella baccata Fusarium lateritium [anamorph]Gray mold rot Botrytis cinereaLate leaf spot Cercospora minimaMucor fruit rot Mucor spp. Mucor piriformisMycosphaerella leaf spot (ashy leaf spot and fruit spot) Mycosphaerella pyri Mycosphaerella sentina Septoria pyricola [anamorph]Nectria twig blight (coral spot) Nectria cinnabarina Tubercularia vulgaris [anamorph]Pear scab Venturia pyrina Fusicladium pyrorum [anamorph]Perennial canker Neofabraea perennans Cryptosporiopsis perennans [anamorph]Phyllosticta leaf spot Phyllosticta sp. Phytophthora crown and root rot (sprinkler rot) Phytophthora cactorumPink mold rot Trichothecium roseum Cephalothecium roseumPowdery mildew Podosphaera leucotrichaPythium dieback Pythium spp. Rhizopus rot Rhizopus stoloniferRust, American hawthorne Gymnosporangium globosumRust, Kern's pear Gymnosporangium kernianumRust, Pacific Coast pear Gymnosporangium libocedriRust, pear trellis (European pear rust) Gymnosporangium fuscumRust, Rocky Mountain pear Gymnosporangium nelsoniiSide rot Phialophora malorumSilver leaf Chondrostereum purpureumSooty blotch Gloeodes pomigenaThread blight (Hypochnus leaf blight) Corticium stevensii Pellicularia koleroga Hypochnus ochroleucusValsa canker Valsa ceratosperma Cytospora sacculus [anamorph]Wood rot Trametes versicolor and various basidiomycetes Xylaria root rot Xylaria spp.
Miscellaneous diseases and disorders Miscellaneous diseases and disordersAlfalfa 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 Cork 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 Nematodes, parasiticDagger, American Xiphinema americanum Dagger Xiphinema riveri Xiphinema vuitteneziLesion Pratylenchus spp. Pratylenchus penetransPin Paratylenchus spp. Root-knot Meloidogyne spp.
Viruslike diseases Viruslike diseasesFlemish beauty corky pit Virus suspected Pear blister canker Virus suspected Pear decline PhytoplasmaPear 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
References Common Names of Diseases, The American Phytopathological Society