Biology Reference
In-Depth Information
Inoculation
. Placing of inoculum in infection
court.
Inoculum
. Pathogen or its part, as spores, frag-
ments of mycelium, etc., that can infect plants.
Inoperculate
. Not opening by a lid.
Intercellular
. Between cells.
Intracellular
. Within cells.
Intumescenc
e. Knoblike or pustulelike outgrowth
of elongated cells on leaves, stems, etc.,
caused by environmental disturbances.
Lamella
. Gill.
Lesion
. Localized spot of diseased tissue.
Locule
. A cavity, especially one in a stroma.
Macroconidia
. Large conidia.
Macroscopic
. Large enough to be seen with the
naked eye.
Medulla
. Loose layer of hyphae inside a thallus;
body of a sclerotium.
Microconidia
. Very small spores, now consid-
ered spermatia of a fungus also having larger
conidia.
Micron
. 1/1000 millimeter, unit used for measur-
ing spores.
Microscopic
. Too small to be seen except with
the aid of a microscope; true of most of the
fungus structures shown in line drawings in
this topic.
Mildew
. Plant disease in which the pathogen is
a growth on the surface.
Molds
. Fungi with conspicuous mycelium or
spore masses, often saprophytes.
Monoecious
. Male and female reproductive
organs in same individual; in rusts, all stages
of life cycle on single species of plant.
Multinucleate
. Several nuclei in same cell.
Mummy
. Dried, shriveled fruit, result of disease.
Muriform
. Having cross and longitudinal septa.
Mushroom
. An agaric fruit body (Fig. 4, p. 41).
Mycelium
, pl.
Mycelia
. Mass of fungus hyphae.
Mycelia Sterilia
. Fungi Imperfecti where spores,
except for chlamydospores, are not present.
Mycoplasmalike Organism
(MLO). A walless
prokaryotic
Necrotic
. As an adjective, killing.
Nematicide
. Chemical or physical agent killing
nematodes.
Nematodes
. Nemas, roundworms, eelworms,
cause of some plant diseases.
Obligate Parasite
. A parasite that can develop
only in living tissues, with no saprophytic
stage.
Obovate
. Inversely ovate, narrowest at base.
Obtuse
. Rounded or blunted, greater than a right
angle.
Oogonium
, pl.
Oogonia
. Female sex organ in the
Oomycetes (Fig. 1, p. 35).
Oomycetes
. Subclass of the Phycomycetes, gam-
etangia of unequal size.
Oospore
. Resting spore formed in a fertilized
oogonium.
Operculate
. With a cover or lid, as in some asci.
Ostiole
. Porelike mouth or openings in papilla or
neck of a perithecium or pycnidium.
Papilla
,
pl.
Papillae
.
Small,
nipplelike
projection.
Paraphysis
, pl.
Paraphyses
. A sterile hyphal ele-
ment in the hymenium, especially in the Asco-
mycetes, usually clavate or filiform.
Paraphysoids
. Threads of hyphal tissue between
asci, like delicate paraphyses but without free
ends.
Parasite
. An organism that lives on or in a second
organism, usually causing disease in the latter.
Pathogen
. Any organism or
factor causing
disease.
Pathogenic
. Capable of causing disease.
Pedicel
. Small stalk.
Perfect State
. Stage of life-cycle in which spores
are
formed
after
nuclear fission. See
Teleomorph.
Peridium
. Wall or limiting membrane of
a sporangium or other fruit body, or of a rust
sorus.
Perithecium
. Subglobose or flasklike ascocarp of
the Pyrenomycetes (Fig. 3, p. 37).
Phialide
. A cell that develops one or more open
ends from which a basipetal succession of
conidia develops without an increase in length
of the phialide itself.
Physiogenic Disease
. Caused by unfavorable
environmental factors.
plant
pathogen which
has
a single-unit membrane. See Phytoplasma.
Mycorrhiza
, pl.
Mycorrhizae
. Symbiotic, non-
pathogenic association of fungi and roots.
Necrosis
. Death of plant cells, usually resulting in
tissue turning dark.
