Glossary

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The specialized fungal hyphal branch that bears the conidium.

Conidiophore

Asexual spore formed by abstriction and detachment of part of a hyphal cell at the end of a conidiophore and germinating by a germ tube.

Conidium

A cluster of erect fungus filaments (hyphae) that are joined together to form a column and that bear asexual spores (conidia).

A cultivated plant variety or cultural selection. Used synonymously with variety.

The distortion, fluting, and puffing of a leaf resulting from the unequal development of its two sides.

Peach Leaf Curl

the noncellular outer layer of an insect or a nematode; water-repellent, waxy layer of epidermal cells of plant parts, such as leaves, stems, and fruit.

Decay of seeds in the soil (pre-emergent damping-off) or young seedlings before or after emergence (post-emergent damping-off).

Damping-off

Distinctive. A distinguishing characteristic serving to identify or determine the presence of a disease or other condition.

Progressive death of shoots, branches, and roots generally starting at the tips.

Dieback

Having a double set of chromosomes (2n chromosomes) per cell.

The sum of the deviations of the vital functions beyond the latitude of health. (This is just one of many definitions of disease.)

Any agent for destroying the causal agent of disease after infection.

Any agent that removes, kills, or inactivates disease-causing organisms before they can cause infection.

The spread of infectious material (inoculum) from a diseased to a healthy plant by wind, water, humans, insects, animal, machinery, or other means.

Nongrowing (inactive, quiescent) state of a plant.

The underdevelopment of any organ of a plant.

Dwarfing

a swelling or blistering on leaves and other plant parts under conditions of high moisture and restricted transpiration (see also oedema).

a serological test in which the sensitivity of the reaction is increased by attaching an enzyme that produces a colored product to one of the reactants.

an abnormal outgrowth from the surface of a stem or leaf.

Enation

native to a particular place; pertaining to a low and steady level of natural disease occurrence.

Produced inside.

Living within another plant.

Plant disease that causes about the same amount of injury each year.

The study of factors influencing the initiation, development, and spread of infectious disease. Also, the study of disease in populations.

An abnormal downward-curving growth or movement of a leaf, leaf part, or stem.

The widespread and destructive development of a disease on many plants in a community or communities.

Chemical used to eliminate a pathogen from a host or an environment.

Control of disease by eliminating the pathogen after it is already established.

Plants in a given population that remain free of disease where it is prevalent, although they possess no natural inherent resistance to the disease. (See Klendusity).

Yellowing and long, spindly growth as a result of insufficient light.

The description of the cause of disease.

Control of disease by preventing its introduction (e.g., by quarantines) into disease-free areas.

Exclusion

Produced outside.

A substance (usually liquid) formed inside a plant and discharged from diseased or injured tissue. The presence of an exudate often aids in diagnosis (e.g., fire blight bacteria).

An organism that is ordinarily saprophytic but under proper conditions may be parasitic.

An organism that is ordinarily parasitic but under proper conditions may be saprophytic.

A distortion of a plant caused by an injury or infection that results in thin, flattened, and sometimes curved shoots.

Fasciation

A long hairlike or whiplike contractile filament protruding from certain bacterial cells and spores of fungi and that enable movement.

The loss of turgor and the drooping of plant parts, usually following a water deficit. The death of a branch in a tree where the leaves remain attached. In either case, the diseased portion stands out like a flag.

Flagging

A small, white to translucent lesion (spot) visible through a leaf.