glossary of phytopathology glossary of phytopathology 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 intake acervulus (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 precipitation acid rain acropetal actinomycetes the actinobacteria or actinomycetes are a group of gram-positive bacteria. acute acute toxicity aeciospore aecium aflatoxin agar aggressiveness air pollution alkaloids allele allelopathy alternate host alternative hosts alternation of generations amphid amphigynous amphimixis amphimobile anaerobic anamorph (adj. anamorphic; syn. imperfect state) anastomosis (pl. anastomoses) anthracnoes antibiotic antibody antigen antiseptic apothecium the apothecium is an open, cuplike, or saucer-shaped sexual fungal fruiting body (ascocarp) containing asci. antiseptic appressorium (pl. appressoria) arbuscular mycorrhiza (abbr. am; syn. endomycorrhiza) arbuscule ascocarp (syn. ascoma) ascogenous ascogonium (pl. ascogonia) ascoma (pl. ascomata; syn. ascocarp) ascomycetes asci ascospore ascostroma (pl. ascostromata) ascus (pl. asci) aseptate asexual asexual reproduction atrophy audpc (abbr. for area under disease progress curve) autotroph avirulence (avr) gene avirulent (syn. nonpathogenic) axenic autoecious b bacilliform bacterial streaming bactericide bacteriocin bacteriophage bacterium (pl. bacteria) bactericide basal 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. basidiospore basidium (pl. basidia) basidiospore basidium (pl. basidia; adj. basidial) binary fission binucleate bioassay biocide biocontrol (syn. biological control) biotic a disease caused by a living organism biotroph (syn. obligate parasite) biotype bitunicate blasting blight blotch breaking broadcast application brooming brown rot (of wood) burn bursa c canker capsid (syn. coat protein) carcinogen carrier casting causal agent certification cfu (abbr. for colony forming unit) chemotaxis (syn. chemotropism) chemotherapy chlamydospore chlamydospore a chlamydospore is the thick-walled big resting spore of several kinds of fungi. chlorosis chronic toxicity chytridiomycetes circulative-propagative transmission (syn. propagative transmission) circulative transmission (syn. persistent transmission) cirrus cleistothecium clamp connection clavate (or claviform) coalesce coat protein (syn. capsid) coccus (pl. cocci) coelomycetes colonization colony colony forming unit (abbr. cfu) compartmentalization conidiogenesis conidiogenous conidioma (pl. conidiomata) conidiophore conidium (pl. conidia) conjugation conk constitutive contact fungicide (syn. protectant fungicide) coremium (pl. coremia; syn. synnema) cross-protection crozier cryptobiosis (hidden life) curl cyst cytopathology d damping-off days to harvest decay degree-day demicyclic deuteromycetes (syn. fungi imperfecti) diagnostic antigen diploid diploid (2x) cells have two copies (homologs) of each chromosome, usually one from the mother and one from the father. diapause dieback (v. die back) differential host (syn. differential cultivar) differential medium differentiation dikaryon (adj. dikaryotic) dilution plating dilution streaking dimorphic direct penetration discomycetes disease disease cycle disease incidence disease progress curve disease pyramid disease severity disease triangle disinfect disinfest dispersal (syn. dissemination) dissemination (syn. dispersal) dolipore septum dormancy (adj. dormant) downy mildew drift (of pesticides) drought durable resistance dwarfing e echinulate economic threshold ectomycorrhiza (pl. ectomycorrhizae) ectoparasite ectotrophic elicitor enation encapsidate encyst endemic endogenous endophytic endoconidium (pl. endoconidia) endomycorrhiza (pl. endomycorrhizae; syn. arbuscular mycorrhiza) endoparasite endospore epidemic epidemiology epinasty epiphytotic the epidemic condition of a disease, in a plant population. compare with enphytotic eradicant eradication ergot ergotism erumpent escape etiolation etiology exclusion exogenous exudate f f. sp. (abbr. for forma specialis) facultative parasite facultative saprotroph fasciation fastidious filamentous (syn. filiform) flagellum flagging fleck focus (pl. foci) forest decline forma specialis (abbr. f.sp.; pl. formae speciales) fructification fruiting body fumigant (v. fumigate) fungi imperfecti (syn. deuteromycetes fungicide (adj. fungicidal) chemical designed to kill fungi fungus (pl. fungi) fungistat (adj. fungistatic) inhibits growth of some fungi. fungistasis fusiform g gall gametangium (pl. gametangia) gametophyte gene-for-gene hypothesis general resistance (syn. horizontal resistance, race non-specific resistance) genotype germ theory giant cell girdle giant cells gram-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 stain growth regulator (syn. hormone) gummosis (pl. gummoses) h haploid hardiness haustorium (pl. haustoria) the haustorium is the hyphal tip of a parasitic fungus hemiparasite hermaphrodite (adj. hermaphroditic) heteroecious heterokaryon (adj. heterokaryotic) heterothallic heterotroph holomorph holoparasite homokaryon (adj. homokaryotic) homothallism (adj. homothallic) horizontal resistance (syn. general resistance, race non-specific resistance) host plant host range hyaline hymenium hyperparasite hyperplasia hypertrophy hypersensitive hypersensitive reaction and pathogenicity (hrp) gene hypersensitive response (hr) hypha hyphal sheath (syn. mantle) hyphomycetes hyphopodium hypoplasia hypovirulence 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 immune immunity imperfect fungi (syn. fungi imperfecti, deuteromycetes) imperfect state (syn. anamorph) in planta in situ in vitro in vivo incubation period indicator plant indirect penetration induced induced systemic resistance (isr) infection court infection cushion infection focus infection peg (syn. penetration peg) infection period infectious infective infest (n. infestation) initial inoculum (syn. primary inoculum) injury inoculate (n. inoculation) inoculum (pl. inocula) inoculum density integrated pest management (abbr. ipm) intumescence (syn. edema or oedema) ipm (abbr. for integrated pest management) isolate k klendusity the disease-escaping ability of plants. koch's postulates knot l latent infection latent period leaf dip leaf spot leafroll lesion life cycle lignification local lesion local necrosis lodge m macerate macroconidium (pl. macroconidia) macrocyclic macronutrient mantle (syn. hyphal sheath) mating types mechanical injury mechanical transmission medium (pl. media) melanin microbial microclimate microconidium (pl. microconidia) microcyclic microflora micronutrient microorganism (syn. microbe) microsclerotium mildew mlo (syn. mycoplasmalike organism) mold mollicute monocyclic monoecious monogenic monogenic resistance (syn. single gene resistance) monotrichous monoxenic culture mosaic motile mottle movement protein multigenic resistance (syn. polygenic resistance) multiline multinucleate multiparticulate virus multipartite virus multiseptate mummification mummy mushroom mutagen mycelia sterilia mycelium (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. mycology mycoparasite mycoplasmalike organism (syn. mlo) mycorrhiza (pl. mycorrhizae; adj. mycorrhizal) mycotoxin mycovirus myxomycetes (syn. slime molds) n necrosis (adj. necrotic) necrotroph needle 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 oxides noninfectious disease nonpathogenic (syn. avirulent) nonpersistent transmission (syn. stylet-borne transmission) nonseptate o obligate parasite (syn. biotroph) occlusion oedema (also edema; syn. intumescence) oligogenic resistance oogonium (pl. oogonia) an oogonium is a female gametogonium. oomycetes (adj. oomycetous) oospore ooze ostiole (adj. ostiolate) overwinter p pandemic papilla paragynous parasexualism parasite (adj. parasitic) parasitism parthenogenesis (adj. parthenogenetic) partial resistance pasteurization pathogen (adj. pathogenic) pathogenesis-related (pr) proteins pathogenicity pathology pathotype pathovar (abbr. pv.) penetration penetration peg (syn. infection peg) perfect (see teleomorph) perithecium (pl. perithecia) peritrichate persistent transmission (syn. circulative transmission) pest pesticide phenological synchrony phenotype phloem necrosis phycomycete phyllody phylloplane-competent physiogenic disease phytoalexin phytopathogenic phytopathology (syn. plant pathology) phytoplasma (syn. mycoplasmalike organism, mlo) phytosanitary certificate phytotoxic plant pathology (syn. phytopathology) plasmodiophoromycetes plasmodium (pl. plasmodia) polycyclic polyetic polygenic resistance (syn. multigenic resistance) polymorphism polyprotein powdery mildew predispose (n. predisposition) primary inoculum (syn. initial inoculum) proinhibitin prokaryote promycelium (pl. promycelia) propagative transmission (syn. circulative propagative transmission) propagule protectant protectant fungicide (syn. contact fungicide) pseudothecium (pl. pseudothecia) puccinia pathway pustule pv. (abbr. for pathovar) pycnidiospore pycnium (pl. pycnia; syn. spermagonium) q qualitative resistance quantitative resistance quarantine quiescent quiescent dormant or inactive quorum sensing r race race non-specific resistance (syn. general resistance, horizontal resistance) receptive hypha reniform resinosis resistant (n. resistance) rhizomorph rhizosphere rhizosphere-competent ringspot rosette rot roundworm rugose russet rust s sanitation sap transmission saprobe (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. scab scald sclerenchyma (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. scorch secondary infection secondary inoculum secondary metabolite secondary organism seed treatment seedborne selective medium septate serrate sessile seta (pl. setae) sexual spore sexually compatible shot-hole sign single gene resistance (syn. monogenic resistance) slime molds (syn. myxomycetes) smut soft rot soil drench soilborne soil pasteurization soil sterilization solarization sooty mold sorus (pl. sori) sp. (abbr. for species; pl. spp.) species specific resistance (syn. vertical resistance) spermagonium (pl. spermagonia; syn. pycnium for rust fungi) spermatium (pl. spermatia; syn. pycniospore for rust fungi) spicule spiroplasma - helical, motile, cell wall-less bacterium; member of genus spiroplasma in class mollicutes sporangiophore sporangiospore sporangium (pl. sporangia) spore sporidium (pl.sporidia) sporocarp spore-bearing fruiting body sporodochium (pl.sporodochia) sporogenous sporophore sporophyte sporulate spot stabilizing selection staghead stem pitting sterigma (pl. sterigmata) sterilant sterile fungus sterilization (adj. sterilized) stippling strain streak striate (n. striations) stroma (pl. stromata) stunting stylet knob (syn. basal knob) stylet-borne transmission (syn. nonpersistent transmission) subspecies substrate sunscald or sunburn suppressive soil susceptible (n. susceptibility) symptom symptomless carrier syncytium (pl. syncytia) synergism (adj. synergistic) synnema (pl. synnemata; syn. coremium) systematics systemic systemic 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 wilt thallus thermotherapy tolerance (adj. tolerant) toxicity toxin transmit (n. transmission) trap crop transmit (n. transmission) trenching tumor (syn. gall) type u urediniospore (also urediospore, uredospore) uredinium (also uredium; pl. uredinia) v vascular wilt disease vector vein banding vein clearing vermiform vertical resistance (syn. specific resistance) viable (n. viability) virescence virion viroid viroplasm virulence virulent viruliferous virus-laden, usually applied to insects or nematodes as vectors virus 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-off water-soaked white rot (of wood) white rust wild type wilt winterburn witches' broom wound x xlb (xylem-limited fastidious bacteria) xylem-limited fastidious bacteria (xlb) y yellowing yellows z zonate zoosporangium zoospore a zoospore is a motile asexual spore utilizing a flagellum for locomotion. zygomycetes zygospore 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.