Small Grain Disease Vocabulary

Glossary from: Common Diseases of Small Grain Cereals - A Guide to Identification, F.J Zillinksy, CIMMYT

Acervulus

Saucer-shaped, exposed fruiting structure that produces conidia from a compact layer of conidiophores, often surrounded by spines

Aeciospores

Spores in a chainlike series within an aecium

Aecium

the fruiting body of rust fungi

Alternate host

a second host species required by some rusts and other organisms to complete their life cycle

Apical cell

the cell located at the tip or apex

Apices

plural of apex

Ascocarp

a mature fungal fruiting body containing asci and ascospores

Ascomyete

a class of fungi that produces ascospores within a saclike ascus

ascospore

a spore produced within a saclike structure (the ascus)

ascus

an oval or rubular spore sac containing ascospores

aseptate

without cross walls (septa)

asecual spores

a spore produced by cell division, which is capable of developing without conjugation into a new individual

avirulent

nonpathogenic

basal cell

the cell at the foot or basof a conidium or conidiophore

basidial state

the part of the life cycle of basidiomycetes during which haploid spores are formed

Basidiomycete

a class of fungi that produce sexual spores on a basidium

basidiospore

a haploid secual spore produced on a basidium

basidium

a short threadlike structure, produced by germinating teliospores, which gives rise to basidiospores or sporidia; also called promycelium in the smut fungi

chlamydospores

a thick-walled, resiting spore

chlorosis

yellowing or whitening of the normally green tissue of plants

cirgus

a ribbonlike column of spores extruded from the ostioles of pycnidia or perithecia

clavate

club shaped

cleistothecium

a closed fruiting structure containing asci

conidiophore

a threadlike stalk upon which conidia are produced

conidium

any sexual spore formed on a conidiophore

diploid

having two sets of chromosomes

echinulate

having short projections on the surface of spores

ellipsoid

shaped like an ellipse or oval

enation

a disease condition in which deformed tissue or galls develop on plant leaves or stems

epiphytotic

the sporadic recurrence of a disease, usually over a wide area and affecting large numbers of susceptible plants

erumpent

the ability of some fungi to grow vigorously from beneath the leaf surface, bursting through and rising above the epidemis

etiology

all the factors contributing the the cause of a disease

extrude

to release or discharge spores

exudate

accumulation of spores or bacterial ooze

facultative parasite

a saprophytic organism capable of behaving as a pathogen

filiform

threadlike

filamentous

also threadlike

flexuous

having bends or waves

foot rot

disease symptoms, such as discoloration, necrosis and decat, affecting the roots and basal portions of the plant

fruiting body

the structure from which spores are produced

fungicide

a chemical or toxin that kills or inhibits fungi

fusoid

tapering toward the ends

gall

an abnormal growth or swelling, usually caused by pathogenic organisms, nematodes, or insects

germ tube

the hypha of a germinating spore

globose

more or less spherical in shape

haploid

having one set of chromosomes

haustorium

a specialized structure for extracting nutrients that is formed on some fungal hyphae following plant cell penetration

herbicide

a chemical that is toxic to some herbacious plants

honeydew

a sticky exudate (containing conidia) produced during one stge of the life cycle of Claviceps purpurea

hyaline

transparent or colorless

hymenium

the layer of a fruiting body that produces spores

hypha

a tubular threadlike filament of fungal mycelium

immune

not affected by pathogens

imperfect state

the asexual period during the life cycle of a fungus

inoculum

spores of other disease material that may cause infection

isolate

a culture of an organsim

latent

the lack of visible symptoms following infection

lesion

a visable area of diseased tissure on an infected plant

macroconidia

the larger, an dusually more common, of the conidia produced by fungi

microconidia

the smaller of the conidia produced by fungi

morphology

referrring to the form or structure of an organism

mosaic

a pattern of disease symptoms displaying mixed green and white pathes

motile

capable of movement

multiseptate

having several septa (crosswalls)

mycelium

a mass of hyphae that form the body of a fungus

mycoplasma

minute unicellular organisms that are smaller than bacteria, variable in shape, and lack rigid cell walls

necrosis

death of plant tissue, usually accompanied by discoloration

obligate parasite

an organism that develops only on living host tissue

oospre

thick-walled, resting spore of Phycomycetes

ostiole

a pore or opening on pycnidia or perithecia through which spores are released

ovoid

egg shaped

pathogen

a microorganisms that causes disease

pathogenic

capable of causing disease

pathogenicity

capacity for causing disease

perfect stage

sexual stage of reproduction

perithecium

a closed ascocarp having an ostiole or opening

persistant

pertaining to viruses that remain infections in insect vectors for long periods

Phycomycetes

a large class of fungi that range in form from an undifferentiated mass to a well-developed mycelium with many branches

physiological forms

groups within species that are morphologically similar, but differ in pathogenicity or other characteristics

primary inoculum

spores or fragments of mycelium capable of initiating a disease

promycelium

hypha of a germinating teliospore on which basidiospores are produced

pusutle

a spore mass developing below the epidermis, usually breaking through at maturity

pycnidium

a flask shaped fruiting body producing asexual spores

race

a group of organisms within a species that is distinguished by its pathogenicity

resistance

inherent capacity of a host plant to prevent or retard the development of disease

resting spore

a spore that remains dormant fro a period of time before germination

reticulate walls

spore walles having a pattern of superficial lines or ridges

rosette

a very short, bunchy growth

saprophyte

an organism that uses dead organic matter as food

sclerotium

a dense compact mycelial mass capable of remaining dormant fro extended periods of time

senescence

the phase of plant growth that extends from full maturity to death

septum

a cross wall or patition

serology

a technique for identifying antigens and antibodies

seta

short hairlike tufts

sexual spore

a spore produced during the sexual stage of the fungal life cycle

sign

fruiting structures or other features of the pathogen that are visible on the host plant

sorus

a spore mass erupting though, or replacing, host tissue

sporangium

a compact funal mass within which spores that are usually asexual are porduced

spore

a minute reporductive unit in fungi and lower plant forms

sporoidium

the haploid sexual spore developing from a basidium; a basidiospore