Glossary of phytopathology explained

This is a glossary of some of the terms used in phytopathology.

Phytopathology is the study of plant diseases. It is a multi-disciplinary science since prerequisites for disease development are the presence of a susceptible host species, a pathogen and the appropriate environmental conditions. This is known as the disease triangle. Because of this interaction, the terminology used in phytopathology often comes from other disciplines including those dealing with the host species (botany / plant science, plant physiology), the pathogen (bacteriology, mycology, nematology, virology), the environment and disease management practices (agronomy, soil science, meteorology, environmental science, ecology, plant breeding, pesticides, entomology), and areas of study that apply to both the host and pathogen (molecular biology, genetics, molecular genetics). The result is that most phytopathological glossary include terms from these other disciplines in addition to terms (disease incidence, horizontal resistance, gene-for-gene relationship, blast, scab and so on) that are specific to, or which have a unique meaning in phytopathology. This glossary is no exception. However, for the sake of brevity, it has, for the most part, restricted terms from other disciplines to those that pertain to the pathogen. At some point, these terms should be moved to other glossaries (e.g. glossary of mycology, glossary of nematology, and so on).

A

abiotic

Disease not caused by living organisms

acceptable daily intakeacervulus (pl. acervuli)

The acervulus is an erumpent, cushionlike fruiting body bearing conidiophores, conidia, and sometimes setae. It is distinguished from a stroma in not having a peridium or covering of fungal tissue of any kind.

acid precipitationacid rainacropetalActinomycetes

The Actinobacteria or Actinomycetes are a group of Gram-positive bacteria.

acuteacute toxicityaeciosporeaeciumaflatoxinagaraggressivenessair pollutionalkaloidsalleleallelopathyalternate hostalternative hostsalternation of generationsamphidamphigynousamphimixisamphimobileanaerobicanamorph (adj. anamorphic; syn. imperfect state)anastomosis (pl. anastomoses)anthracnoesantibioticantibodyantigenantisepticapothecium

The apothecium is an open, cuplike, or saucer-shaped sexual fungal fruiting body (ascocarp) containing asci.

antisepticappressorium (pl. appressoria)arbuscular mycorrhiza (abbr. AM; syn. endomycorrhiza) arbusculeascocarp (syn. ascoma)ascogenousascogonium (pl. ascogonia)ascoma (pl. ascomata; syn. ascocarp)Ascomycetesasciascosporeascostroma (pl. ascostromata) ascus (pl. asci) aseptateasexualasexual reproductionatrophyAUDPC (abbr. for Area Under Disease Progress Curve)autotrophavirulence (avr) geneavirulent (syn. nonpathogenic)axenicautoecious

B

bacilliformbacterial streamingbactericidebacteriocinbacteriophagebacterium (pl. bacteria)bactericidebasal knob (syn. stylet knob)basidiocarp (syn. basidioma)Basidiomyctes

The Division Basidiomycota is a large taxon within the Kingdom Fungi that includes those species that produce spores in a club-shaped structure called a basidium.

basidiosporebasidium (pl. basidia)basidiosporebasidium (pl. basidia; adj. basidial)binary fissionbinucleatebioassaybiocidebiocontrol (syn. biological control)biotic

A disease caused by a living organism

biotroph (syn. obligate parasite)biotypebitunicateblastingblightblotchbreakingbroadcast applicationbroomingbrown rot (of wood)burnbursa

C

cankercapsid (syn. coat protein)carcinogencarriercastingcausal agentcertificationcfu (abbr. for colony forming unit)chemotaxis (syn. chemotropism) chemotherapychlamydosporechlamydospore

A chlamydospore is the thick-walled big resting spore of several kinds of fungi.

chlorosischronic toxicitychytridiomycetescirculative-propagative transmission (syn. propagative transmission) circulative transmission (syn. persistent transmission) cirruscleistotheciumclamp connectionclavate (or claviform)coalescecoat protein (syn. capsid) coccus (pl. cocci)coelomycetescolonizationcolonycolony forming unit (abbr. cfu)compartmentalizationconidiogenesisconidiogenousconidioma (pl. conidiomata)conidiophoreconidium (pl. conidia) conjugationconkconstitutivecontact fungicide (syn. protectant fungicide)coremium (pl. coremia; syn. synnema)cross-protectioncroziercryptobiosis (hidden life)curlcystcytopathology

D

damping-offdays to harvestdecaydegree-daydemicyclicdeuteromycetes (syn. Fungi Imperfecti)diagnosticantigendiploid

Diploid (2x) cells have two copies (homologs) of each chromosome, usually one from the mother and one from the father.

diapausedieback (v. die back)differential host (syn. differential cultivar)differential mediumdifferentiationdikaryon (adj. dikaryotic)dilution platingdilution streakingdimorphicdirect penetrationDiscomycetesdiseasedisease cycledisease incidencedisease progress curvedisease pyramiddisease severitydisease triangledisinfectdisinfestdispersal (syn. dissemination) dissemination (syn. dispersal)dolipore septumdormancy (adj. dormant)downy mildewdrift (of pesticides)drought durable resistancedwarfing

E

echinulateeconomic thresholdectomycorrhiza (pl. ectomycorrhizae) ectoparasite ectotrophicelicitorenationencapsidateencystendemicendogenousendophyticendoconidium (pl. endoconidia)endomycorrhiza (pl. endomycorrhizae; syn. arbuscular mycorrhiza) endoparasiteendosporeepidemicepidemiologyepinastyepiphytotic

The epidemic condition of a disease, in a plant population. Compare with enphytotic

eradicanteradicationergotergotismerumpentescapeetiolationetiologyexclusionexogenousexudate

F

f. sp. (abbr. for forma specialis)facultative parasitefacultative saprotrophfasciationfastidiousfilamentous (syn. filiform) flagellumflaggingfleckfocus (pl. foci) forest declineforma specialis (abbr. f.sp.; pl. formae speciales) fructificationfruiting bodyfumigant (v. fumigate)Fungi Imperfecti (syn. Deuteromycetesfungicide (adj. fungicidal)

Chemical designed to kill fungi

fungus (pl. fungi)fungistat (adj. fungistatic)

Inhibits growth of some fungi.

fungistasisfusiform

G

gallgametangium (pl. gametangia)gametophytegene-for-gene hypothesisgeneral resistance (syn. horizontal resistance, race non-specific resistance)genotypegerm theorygiant cellgirdlegiant cellsgram-negative

Gram-negative bacteria are those that do not retain crystal violet dye in the Gram staining protocol.

gram-positive

Gram-positive bacteria are classified as bacteria that retain a crystal violet dye during the Gram stain process.

gram staingrowth regulator (syn. hormone) gummosis (pl. gummoses)

H

haploidhardinesshaustorium (pl. haustoria)

The haustorium is the hyphal tip of a parasitic fungus

hemiparasitehermaphrodite (adj. hermaphroditic) heteroeciousheterokaryon (adj. heterokaryotic) heterothallicheterotrophholomorphholoparasitehomokaryon (adj. homokaryotic) homothallism (adj. homothallic)horizontal resistance (syn. general resistance, race non-specific resistance)host planthost rangehyalinehymeniumhyperparasitehyperplasiahypertrophyhypersensitivehypersensitive reaction and pathogenicity (hrp) genehypersensitive response (HR) hyphahyphal sheath (syn. mantle)hyphomyceteshyphopodiumhypoplasiahypovirulence

hypovirulence is reduced virulence of a pathogen. Hypovirulence in fungi can be caused by a virus within the fungus. The virus reduces virulence and sporulation. A hypovirus-fungus can be used in biological control.

I

immuneimmunityimperfect fungi (syn. Fungi Imperfecti, deuteromycetes)imperfect state (syn. anamorph)in plantain situin vitroin vivoincubation periodindicator plantindirect penetrationinducedinduced systemic resistance (ISR)infection courtinfection cushioninfection focusinfection peg (syn. penetration peg) infection periodinfectiousinfectiveinfest (n. infestation) initial inoculum (syn. primary inoculum)injuryinoculate (n. inoculation)inoculum (pl. inocula)inoculum densityintegrated pest management (abbr. IPM)intumescence (syn. edema or oedema) IPM (abbr. for integrated pest management) isolate

K

klendusityThe disease-escaping ability of plants.Koch's postulatesknot

L

latent infectionlatent periodleaf dipleaf spotleafrolllesionlife cyclelignificationlocal lesionlocal necrosislodge

M

maceratemacroconidium (pl. macroconidia) macrocyclicmacronutrientmantle (syn. hyphal sheath) mating typesmechanical injurymechanical transmissionmedium (pl. media) melaninmicrobialmicroclimatemicroconidium (pl. microconidia) microcyclicmicrofloramicronutrientmicroorganism (syn. microbe)microsclerotium mildewMLO (syn. mycoplasmalike organism) moldmollicutemonocyclicmonoeciousmonogenicmonogenic resistance (syn. single gene resistance)monotrichousmonoxenic culturemosaicmotilemottlemovement proteinmultigenic resistance (syn. polygenic resistance)multilinemultinucleatemultiparticulate virusmultipartite virusmultiseptatemummificationmummymushroommutagenMycelia steriliamycelium (pl. mycelia)

Mycelium is the vegetative part of a fungus consisting of a mass of branching, threadlike hyphae that exists below the ground or within another substrate.

mycologymycoparasitemycoplasmalike organism (syn. MLO) mycorrhiza (pl. mycorrhizae; adj. mycorrhizal) mycotoxinmycovirusMyxomycetes (syn. slime molds)

N

necrosis (adj. necrotic) necrotrophneedle cast (of conifers) nematicide

A nematicide is a type of chemical pesticide used to kill parasitic nematodes.

nematode

Nematodes are unsegmented, bilaterally symmetric and triploblastic protostomes with a complete digestive system.

nitrogen oxidesnoninfectious diseasenonpathogenic (syn. avirulent) nonpersistent transmission (syn. stylet-borne transmission)nonseptate

O

obligate parasite (syn. biotroph)occlusionoedema (also edema; syn. intumescence) oligogenic resistanceoogonium (pl. oogonia)

An oogonium is a female gametogonium.

oomycetes (adj. oomycetous)oosporeoozeostiole (adj. ostiolate)overwinter

P

pandemicpapillaparagynousparasexualismparasite (adj. parasitic)parasitismparthenogenesis (adj. parthenogenetic)partial resistancepasteurizationpathogen (adj. pathogenic) pathogenicitypathologypathotypepathovar (abbr. pv.) penetrationpenetration peg (syn. infection peg) perfect (see teleomorph)perithecium (pl. perithecia)peritrichatepersistent transmission (syn. circulative transmission) pestpesticidephenological synchronyphenotypephloem necrosisPhycomycetephyllodyphylloplane-competentphysiogenic diseasephytoalexinphytopathogenicphytopathology (syn. plant pathology) phytoplasma (syn. mycoplasmalike organism, MLO) phytosanitary certificatephytotoxicplant pathology (syn. phytopathology) plasmodiophoromycetesplasmodium (pl. plasmodia) polycyclicpolyeticpolygenic resistance (syn. multigenic resistance)polymorphismpolyproteinpowdery mildewpredispose (n. predisposition)primary inoculum (syn. initial inoculum) proinhibitinprokaryotepromycelium (pl. promycelia) propagative transmission (syn. circulative propagative transmission) propaguleprotectantprotectant fungicide (syn. contact fungicide)pseudothecium (pl. pseudothecia)Puccinia pathwaypustulepv. (abbr. for pathovar)pycnidiosporepycnium (pl. pycnia; syn. spermagonium)

Q

qualitative resistancequantitative resistancequarantinequiescentquiescentdormant or inactivequorum sensing

R

racerace non-specific resistance (syn. general resistance, horizontal resistance)receptive hyphareniformresinosisresistant (n. resistance) rhizomorphrhizosphererhizosphere-competentringspotrosetterotroundwormrugoserussetrust

S

sanitationsap transmissionsaprobe (syn. saprotroph)saprotroph

A saprotroph (or saprobe) is an organism that obtains its nutrients from non-living organic matter, usually dead and decaying plant or animal matter, by absorbing soluble organic compounds.

scabscaldsclerenchyma (adj. sclerenchymatous)sclerotium (pl. sclerotia)

A sclerotium is a compact mass of hardened mycelium (as an ergot) stored with reserve food material that in some higher fungi becomes detached and remains dormant until a favorable opportunity for growth occurs.

scorchsecondary infectionsecondary inoculumsecondary metabolitesecondary organismseed treatmentseedborneselective medium septateserratesessileseta (pl. setae)sexual sporesexually compatibleshot-holesignsingle gene resistance (syn. monogenic resistance)slime molds (syn. Myxomycetes)smutsoft rotsoil drenchsoilbornesoil pasteurizationsoil sterilizationsolarizationsooty moldsorus (pl. sori)sp. (abbr. for species; pl. spp.)speciesspecific resistance (syn. vertical resistance)spermagonium (pl. spermagonia; syn. pycnium for rust fungi) spermatium (pl. spermatia; syn. pycniospore for rust fungi)spiculespiroplasma – helical, motile, cell wall-less bacterium; member of genus Spiroplasma in class Mollicutessporangiophoresporangiosporesporangium (pl. sporangia)sporesporidium (pl.sporidia)sporocarpspore-bearing fruiting bodysporodochium (pl.sporodochia)sporogenoussporophoresporophytesporulatespotstabilizing selectionstagheadstem pittingsterigma (pl. sterigmata)sterilantsterile fungussterilization (adj. sterilized)stipplingstrainstreakstriate (n. striations)stroma (pl. stromata)stuntingstylet knob (syn. basal knob)stylet-borne transmission (syn. nonpersistent transmission)subspeciessubstratesunscald or sunburnsuppressive soilsusceptible (n. susceptibility)symptomsymptomless carriersyncytium (pl. syncytia)synergism (adj. synergistic)synnema (pl. synnemata; syn. coremium)systematicssystemicsystemic acquired resistance (SAR) systemic fungicide

T

teleomorph (syn. perfect state)teliospore (sometimes called teleutospore, teleutosporodesm)

Teliospore (sometimes called teleutospore) is the thick-walled resting spore of some fungi (rusts and smuts), from which the basidium arises.

telium (pl. telia)temporary wiltthallusthermotherapytolerance (adj. tolerant) toxicitytoxintransmit (n. transmission)trap croptransmit (n. transmission)trenching tumor (syn. gall)type

U

urediniospore (also urediospore, uredospore) uredinium (also uredium; pl. uredinia)

V

vascular wilt diseasevectorvein bandingvein clearingvermiformvertical resistance (syn. specific resistance)viable (n. viability)virescencevirionviroidviroplasmvirulencevirulentviruliferousvirus-laden, usually applied to insects or nematodes as vectorsvirus

A virus is a microscopic particle (ranging in size from 20 – 300 nm) that can infect the cells of a biological organism.

viscin

W

walling-offwater-soakedwhite rot (of wood)white rustwild typewiltwinterburnwitches' broomwound

X

XLB (xylem-limited fastidious bacteria)xylem-limited fastidious bacteria (XLB)

Y

yellowingyellows

Z

zonatezoosporangiumzoospore

A zoospore is a motile asexual spore utilizing a flagellum for locomotion.

Zygomyceteszygospore

A zygospore is a sexual part of a fungus, a chlamydospore that is created by the nuclear fusion of haploid hyphae of different mating types.

Glossary of phytopathology explained

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B

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I

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M

N

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References