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).
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abiotic
acceptable daily intake
acervulus (pl. acervuli)
acid precipitation
acid rain
acropetal
Actinomycetes
acute
acute toxicity
aeciospore
aecium
aflatoxin
agar
aggressiveness
air pollution
alkaloids
allele
allelopathy
alternate host
alternative hosts
alternation of generations
amphid
amphimixis
amphimobile
anaerobic
anamorph (adj. anamorphic; syn. imperfect state)
anastomosis (pl. anastomoses)
anthracnoes
antibiotic
antibody
antigen
antiseptic
apothecium
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
bacilliform
bacterial streaming
bactericide
bacteriocin
bacteriophage
bacterium (pl. bacteria)
bactericide
basal knob (syn. stylet knob)
basidiocarp (syn. basidioma)
Basidiomyctes
basidiospore
basidium (pl. basidia)
basidiospore
basidium (pl. basidia; adj. basidial)
binary fission
binucleate
bioassay
biocide
biocontrol (syn. biological control)
biotic
biotroph (syn. obligate parasite)
biotype
bitunicate
blasting
blight
blotch
breaking
broadcast application
brooming
brown rot (of wood)
burn
bursa
canker
capsid (syn. coat protein)
carcinogen
carrier
casting
causal agent
certification
cfu (abbr. for colony forming unit)
chemotaxis (syn. chemotropism)
chemotherapy
chlamydospore
chlamydospore
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
damping-off
days to harvest
decay
degree-day
demicyclic
deuteromycetes (syn. Fungi Imperfecti)
diagnostic
antigen
diploid
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
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
eradicant
eradication
ergot
ergotism
erumpent
escape
etiolation
etiology
exclusion
exogenous
exudate
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)
fungus (pl. fungi)
fungistat (adj. fungistatic)
fungistasis
fusiform
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-positive
gram stain
growth regulator (syn. hormone)
gummosis (pl. gummoses)
haploid
hardiness
haustorium (pl. haustoria)
hemiparasite
hermaphrodite (adj. hermaphroditic)
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
hypoplasia
hypovirulence
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
klendusity The disease-escaping ability of plants.
Koch's postulates
knot
latent infection
latent period
leaf dip
leaf spot
leafroll
lesion
life cycle
lignification
local lesion
local necrosis
lodge
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)
mycology
mycoplasmalike organism (syn. MLO)
mycorrhiza (pl. mycorrhizae; adj. mycorrhizal)
mycotoxin
mycovirus
Myxomycetes (syn. slime molds)
necrosis (adj. necrotic)
necrotroph
needle cast (of conifers)
nematicide
nematode
nitrogen oxides
noninfectious disease
nonpathogenic (syn. avirulent)
nonpersistent transmission (syn. stylet-borne transmission)
nonseptate
obligate parasite (syn. biotroph)
occlusion
oedema (also edema; syn. intumescence)
oligogenic resistance
oogonium (pl. oogonia)
oomycetes (adj. oomycetous)
oospore
ooze
ostiole (adj. ostiolate)
overwinter
pandemic
papilla
parasexualism
parasite (adj. parasitic)
parasitism
parthenogenesis (adj. parthenogenetic)
partial resistance
pasteurization
pathogen (adj. pathogenic)
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)
pycnium (pl. pycnia; syn. spermagonium)
qualitative resistance
quantitative resistance
quarantine
quiescent
quiescent
dormant or inactive
quorum sensing
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
sanitation
sap transmission
saprobe (syn. saprotroph)
saprotroph
scab
scald
sclerenchyma (adj. sclerenchymatous)
sclerotium (pl. sclerotia)
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
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
teleomorph (syn. perfect state)
teliospore (sometimes called teleutospore, teleutosporodesm)
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
urediniospore (also urediospore, uredospore)
uredinium (also uredium; pl. uredinia)
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
walling-off
water-soaked
white rot (of wood)
white rust
wild type
wilt
winterburn
witches' broom
wound
XLB (xylem-limited fastidious bacteria)
xylem-limited fastidious bacteria (XLB)
yellowing
yellows
zoosporangium
zoospore
Zygomycetes
zygospore
Fusarium ear blight (FEB), is a fungal disease of cereals, including wheat, barley, oats, rye and triticale. FEB is caused by a range of Fusarium fungi, which infects the heads of the crop, reducing grain yield. The disease is often associated with contamination by mycotoxins produced by the fungi already when the crop is growing in the field. The disease can cause severe economic losses as mycotoxin-contaminated grain cannot be sold for food or feed.
Botrytis cinerea is a necrotrophic fungus that affects many plant species, although its most notable hosts may be wine grapes. In viticulture, it is commonly known as "botrytis bunch rot"; in horticulture, it is usually called "grey mould" or "gray mold".
Powdery mildew is a fungal disease that affects a wide range of plants. Powdery mildew diseases are caused by many different species of ascomycete fungi in the order Erysiphales. Powdery mildew is one of the easier plant diseases to identify, as the signs of the causal pathogen are quite distinctive. Infected plants display white powdery spots on the leaves and stems. This mycelial layer may quickly spread to cover all of the leaves. The lower leaves are the most affected, but the mildew can appear on any above-ground part of the plant. As the disease progresses, the spots get larger and denser as large numbers of asexual spores are formed, and the mildew may spread up and down the length of the plant.
Black sigatoka is a leaf-spot disease of banana plants caused by the ascomycete fungus Mycosphaerella fijiensis (Morelet), also known as black leaf streak. It was discovered in 1963 and named for its similarities with yellow Sigatoka, which is caused by Mycosphaerella musicola (Mulder), which was itself named after the Sigatoka Valley in Fiji. In the same valley an outbreak of this disease reached epidemic proportions from 1912 to 1923.
Fusarium wilt is a common vascular wilt fungal disease, exhibiting symptoms similar to Verticillium wilt. This disease has been investigated extensively since the early years of this century. The pathogen that causes Fusarium wilt is Fusarium oxysporum. The species is further divided into formae speciales based on host plant.
Plant diseases are diseases in plants caused by pathogens and environmental conditions. Organisms that cause infectious disease include fungi, oomycetes, bacteria, viruses, viroids, virus-like organisms, phytoplasmas, protozoa, nematodes and parasitic plants. Not included are ectoparasites like insects, mites, vertebrates, or other pests that affect plant health by eating plant tissues and causing injury that may admit plant pathogens. The study of plant disease is called plant pathology.
Apple scab is a common disease of plants in the rose family (Rosaceae) that is caused by the ascomycete fungus Venturia inaequalis. While this disease affects several plant genera, including Sorbus, Cotoneaster, and Pyrus, it is most commonly associated with the infection of Malus trees, including species of flowering crabapple, as well as cultivated apple. The first symptoms of this disease are found in the foliage, blossoms, and developing fruits of affected trees, which develop dark, irregularly-shaped lesions upon infection. Although apple scab rarely kills its host, infection typically leads to fruit deformation and premature leaf and fruit drop, which enhance the susceptibility of the host plant to abiotic stress and secondary infection. The reduction of fruit quality and yield may result in crop losses of up to 70%, posing a significant threat to the profitability of apple producers. To reduce scab-related yield losses, growers often combine preventive practices, including sanitation and resistance breeding, with reactive measures, such as targeted fungicide or biocontrol treatments, to prevent the incidence and spread of apple scab in their crops.
Uncinula necator is a fungus that causes powdery mildew of grape. It is a common pathogen of Vitis species, including the wine grape, Vitis vinifera. The fungus is believed to have originated in North America. European varieties of Vitis vinifera are more or less susceptible to this fungus. Uncinula necator infects all green tissue on the grapevine, including leaves and young berries. It can cause crop loss and poor wine quality if untreated. The sexual stage of this pathogen requires free moisture to release ascospores from its cleistothecia in the spring. However, free moisture is not needed for secondary spread via conidia; high atmospheric humidity is sufficient. Its anamorph is called Oidium tuckeri.
Venturia inaequalis is an ascomycete fungus that causes the apple scab disease.
Eyespot is an important fungal disease of wheat caused by the necrotrophic fungus Tapesia yallundae and Tapesia acuformis. It is also called Strawbreaker. Eyespot is more severe where wheat is grown continuously and when the weather is cool and moist. Treating crops against eyespot with fungicide costs millions to farmers and is complicated by the pathogen becoming resistant to the more commonly used fungicides. Severe cases of the disease can reduce yield by up to 40%. It is most common in temperate regions such as North and South America, Europe, Australia, New Zealand and Africa.
Thielaviopsis basicola is the plant-pathogen fungus responsible for black root rot disease. This particular disease has a large host range, affecting woody ornamentals, herbaceous ornamentals, agronomic crops, and even vegetable crops. Examples of susceptible hosts include petunia, pansy, poinsettia, tobacco, cotton, carrot, lettuce, tomato, and others. Symptoms of this disease resemble nutrient deficiency but are truly a result of the decaying root systems of plants. Common symptoms include chlorotic lower foliage, yellowing of plant, stunting or wilting, and black lesions along the roots. The lesions along the roots may appear red at first, getting darker and turning black as the disease progresses. Black root lesions that begin in the middle of a root can also spread further along the roots in either direction. Due to the nature of the pathogen, the disease can easily be identified by the black lesions along the roots, especially when compared to healthy roots. The black lesions that appear along the roots are a result of the formation of chlamydospores, resting spores of the fungus that contribute to its pathogenicity. The chlamydospores are a dark brown-black color and cause the "discoloration" of the roots when they are produced in large amounts.
Zymoseptoria tritici, synonyms Septoria tritici, Mycosphaerella graminicola, is a species of filamentous fungus, an ascomycete in the family Mycosphaerellaceae. It is a wheat plant pathogen causing septoria leaf blotch that is difficult to control due to resistance to multiple fungicides. The pathogen today causes one of the most important diseases of wheat.
Peronospora manshurica is a plant pathogen. It is a widespread disease on the leaves of soybeans and other crop plants. The fungi is commonly referred to as downy mildew, "leafspot", or "leaf-spot".
Phytophthora megakarya is an oomycete plant pathogen that causes black pod disease in cocoa trees in west and central Africa. This pathogen can cause detrimental loss of yield in the economically important cocoa industry, worth approximately $70 billion annually. It can damage any part of the tree, causing total yield losses which can easily reach 20-25%. A mixture of chemical and cultural controls, as well as choosing resistant plant varieties, are often necessary to control this pathogen.
Sporisorium reilianum Langdon & Full., (1978), previously known as Sphacelotheca reiliana, and Sporisorium reilianum, is a species of biotrophic fungus in the family Ustilaginaceae. It is a plant pathogen that infects maize and sorghum.
Helminthosporium solani is a fungal plant pathogen responsible for the plant disease known as silver scurf. Silver scurf is a blemish disease, meaning the effect it has on tubers is mostly cosmetic and affects "fresh market, processing and seed tuber potatoes." There are some reports of it affecting development, meaning growth and tuber yield. This is caused by light brown lesions, which in turn change the permeability of tuber skin and then it causes tuber shrinkage and water loss, which finally causes weight loss. The disease has become economically important because silver scurf affected potatoes for processing and direct consumption have been rejected by the industry. The disease cycle can be divided into two stages: field and storage. It is mainly a seed borne disease and the primary source of inoculum is mainly infected potato seed tubers. Symptoms develop and worsen in storage because the conditions are conducive to sporulation. The ideal conditions for the spread of this disease are high temperatures and high humidity. There are also many cultural practices that favor spread and development. There are multiple ways to help control the disease.
Botrytis fabae is a plant pathogen, a fungus that causes chocolate spot disease of broad or fava bean plants, Vicia faba. It was described scientifically by Mexican-born Galician microbiologist Juan Rodríguez Sardiña in 1929.
Peach scab, also known as peach freckles, is a disease of stone fruits caused by the fungi Cladosporium carpophilum. The disease is most prevalent in wet and warm areas especially southern part of the U.S. as the fungi require rain and wind for dispersal. The fungus causes scabbing, lesions, and defoliating on twig, fruit, and leaf resulting in downgrade of peach quality or loss of fruits due to rotting in severe cases.
Black pod disease is a fungal disease from Cocoa trees. The pathogen, if left untreated can destroy all yields; annually the pathogen can cause a yield loss of up to 1/3 and up to 10% of total trees can be lost completely.
Gnomoniopsis castaneae is a fungus of the order Diaporthales that is the most important cause of brown chestnut rot, an emerging disease that damages the fruit of chestnuts. It also causes cankers and necrosis on leaves and on chestnut galls caused by the gall wasp, Dryocosmus kuriphilus. Additionally, it can cause cankers on other chestnut species, red oak, hazelnut trees, less severe damage to some nut trees, and lives as an endophyte on other nut trees. The disease has been reported in Europe, Oceania, and has recently been found in North America; for this reason, the fungus is considered a potential threat to the reintroduction of the American chestnut.