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F distribution
The sampling distribution of the ratio of two independent quantities each of which is distributed like a sample variance from a normal distribution.

F1
The first filial generation, or the first-generation offspring of a given mating.

F2
The second filial generation. It is in this generation that segregation first occurs.

Facets
The visual units that compose the compound eye.

Facette
Funnel-shaped opening through the inner membrane complex of the egg of a pentastomid; it receives the product of the dorsal organ.

Facial (artery)
The artery which runs along the groove of the jaw bone and the lower edge of the jaw.

Facitious host
An easily grown plant or animal species used as a host for the mass culture of a natural enemy in the insectary but which is not attacked by this enemy in nature.

Factor
An independent variable under examination in an experiment as a possible cause of variation.

Factor comparison
A job evaluation method where each job is ranked in a job hierarchy and a payment hierarchy to derive a ranking of all jobs and wage rates.

Factorial experiment
An experiment designed to examine the effect of one or more factors, each factor being applied at two or more levels. The experiment utilises every combination of factor levels as treatments in the experimental design.

Facultative
The ability of an organism to grow either in the presence of absence of an environmental factor (e.g. facultative aerobe, facultative psychrophile).

Facultative agents
Used by Howard & Fiske to describe agents of destruction which increase their percentage of destruction as population density rises; synonymous with density-dependent factors.

Facultative parasite
An organism that is usually saprophytic but which under certain conditions may become parasitic e.g. a fungus capable of operating at two trophic modes - decomposer and consumer.

Facultative saprophyte
An organism that is usually parasitic but which may also live as a saprophyte.

Facultative symbiont
When facultative, a symbiont is an opportunist, establishing a relationship with a host only if the opportunity presents itself; it is not physiologically dependent on doing so.

Facultative weed
A weed found growing both wild and in association with man.

Fallow
Cropland left idle to restore productivity, primarily through accumulating water or nutrients or both. The soil is tilled for at least one growing season to destroy weeds, to encourage moisture storage, and to promote decomposition of plant residues.

Fan nozzle
See nozzle v.

Farmyard manure
Cattle droppings (faeces) mixed with straw or similar material used as bedding in sheds, barns or night yards. If heaped to rot well before use, farmyard manure does not cause crop burn, increases most crop yields and water-retaining properties of soils.

Fasciation
Hyperplastic symptom characterised by a fusing (and flattening) of such plant organs as stems.

Fasicle
Stylet bundle or combination of mouthparts used to pierce the skin in a blood-feeding arthropod; composition of a fasicle varies according to group.

Fasiculation
Hyperplastic symptom characterised by a clustering of such plant organs as shoots into such structures as 'witches-brooms'.

Fat-corrected milk
Gaines' s formula is an attempt to relate the energy required to produce milks of different fat contents by adjusting the yield to that of a 4% butterfat milk: FCM = 0.4M + 15F(M = milk yield, F = butterfat yield: all in the same units, e.g. all as kg)

Feasibility study
A study, not necessarily quantitative, to determine if an investment proposal can meet corporate objectives.

Fecundity
Reproductive capacity of an organism.

Feedback inhibition
Inhibition by an end product of the biosynthetic pathway involved in its synthesis.

Feedback (loop)
The use of information produced at one stage in a series of operations as input at another, usually earlier, stage.

Feedlot
An area of land, used to accommodate animals (very commonly beef cattle) at a very high density, not contributing at all to the production of animal feed (all of which has therefore to be brought to the animals from outside the feedlot).

Feekes scale
Scale expressing stages in cereal seedling development.

Femoral (artery)
The large artery running down the centre of the inner aspect of the thigh.

Femur
Counting from the body, the third and usually the heaviest segment of an insect's leg.

Feral
A domesticated animal which has returned to the wild state.

Fermentation
The process of growing a selected organism, usually a bacterium, mould or yeast, on substrate so as to bring about a desired change or to generate products of the cells' metabolism (e.g. ethanol and carbon dioxide from yeast fermentation). The term is also used to describe biochemical conversions and catabolic reactions producing ATP.

Fermenter
A large vessel (5,000 to 50,000 gallons) in which industrial fermentations are carried out.

Ferrodoxin
An electron carrier of low reduction potential; small protein containing iron.

Fertile
Capable of producing offspring.

Fertility
Actual capability of an organism to produce living offspring. On a herd basis, best expressed as the number of calves born per year as a percentage of the number of females exposed to the bull in the previous year. May also be expressed as the number of conceptions confirmed by pregnancy diagnosis or the calving percentage of services or inseminations. It may be expressed as the percentage of non-returns (i.e., cows which did not come on heat after insemination) but obviously this is not a satisfactory method.

Fertilisation (plant and animals)
The union of the male gamete or sperm and the female gamete or egg and of their nuclei to form a zygote.

Fertilisation (soil)
The application of nutrients (fertiliser) to soil in order to promote growth and development of plants.

Festoons
Sclerites on the posterior margin of the opisthosoma of certain hard ticks.

Fetch
In an airstream - is the length of its traverse across an area which modifies its properties.

Fetotoxin
A substance that can poison an unborn foetus.

Fibrin
The protein which composes blood clots; formed from the blood protein fibrinogen.

Fibrinous pericarditis
An inflammation of the heart sac characterised by the excess accumulation of a straw-coloured or haemorrhagic fluid containing fibrin, a whitish insoluble protein derived from the blood.

Fibrous root
A thread-like root, as in grasses.

Fibrous root system
Composed of profusely branched roots with many lateral rootlets but with no main or tap root development.

Fidelity
Degree of regularity or 'faithfulness' with which a species occurs in certain plant communities, expressed on a five-part scale: (5) exclusive, (4) selective, (3) preferential, (2) companion, indifferent, (1) accidental, strangers.

Field capacity
The water content of the soil immediately after all 'free water' has been drained by the force of gravity (Hillel, 1980). Typical values range from 10-40 vol% with the lower range generally found in sandy soils and the upper range often associated with clay-type soils.

Field recording form
A form used in collecting field information. Usually in a format compatible with data base management systems, statistical calculations etc.

Field resistance
Resistance observed in the field (usually on mature plants, but not under experimental conditions (usually on seedlings)). A term best avoided, since resistance of this type can now easily be produced experimentally, by using plants of appropriate age under appropriate environmental conditions.

Field scout
A person who samples fields for pest infestations.

Filamentous
Thread-like; many times longer than wide.

Filiform
Thread-like; filamentous.

Filler
Inert component of pesticide dust or granular formulation that acts as a diluent.

Fimbria
Tube-like protein structures on the exterior of some bacteria, which may be involved in attachment to surfaces and the formation of pellicles but are not involved in motility.

Finance budget
A budget showing the borrowings which are needed and interest and principal repayments.

Financial accounting
The recording of financial transactions leading to the preparation of global financial statements, e.g. profit and loss account or balance sheet.

Financially discrete
Characteristic of a R & D project component which makes it easy to calculate costs.

Fine granule
A granule in the particle size range from 300 to 2,500 µm.

Fine spray
A dispersion of drops of 100 to 200 µm volume median diameter. See spray v.

Finite difference
A method in which a derivative is approximated by a difference between a function values over a small finite time difference.

First-best optimum
The absolutely optimal allocation of resources, where all prices are set equal to marginal social cost.

First in first out
A stock valuation system where goods are priced and issued to work in progress on the assumption that the first stock received is issued first.

First-order difference transformation
A first-order difference transformation (Vyt) is a series developed by computing the differences between adjacent values (yt - yt-1) in a time series.

First order process
A chemical process where the rate of reaction is directly proportional to the amount of chemical present.

First-pass effect
Biotransformation of a xenobiotic before it reaches the systemic circulation. The biotransformation of an intestinally absorbed xenobiotic by the liver is referred to as a hepatic first-pass effect.

Fiscal year
That twelve-month period which the government has determined shall be the basis for budgeting all government activities. It may, or may not coincide with the January-December calendar year. It may, or may not coincide with the fiscal year of any other organisation, e.g. a R & D client in the private sector.

Fishbone diagram
A graph used in quality control to identify possible problem causes. Also called an Ishikawa diagram after its inventor.

Fission
Transverse splitting in two of bacterial cells, asexual.

Fixed assets
Physical assets kept by an organisation to carry out its business, e.g. buildings and vehicles.

Fixed budget
A budget which remains unchanged irrespective of the actual level of output.

Fixed capital
Land, buildings, irrigation equipment etc. which cannot easily be moved.

Fixed coppers
Insoluble copper fungicides whose copper is in a combined form. Usually finely divided, relatively insoluble powders.

Fixed overhead absorption rate (FOAR)
A calculation that divides the total fixed overheads of a cost centre by a measure of output such as units, volume, labour hours or machine hours.

Fixed (overhead) costs
Costs which must be met and are not affected by the size of the activities in the farm operations.

Fixed overhead expenditure variance
The difference between the actual cost and the budgeted cost of fixed overheads.

Fixed overhead volume variance
The under- or over-recovery of fixed overheads caused by the actual level of activity varying from the budgeted level used to set the standard absorption rate.

Flacherie
A term used to describe the flaccid condition (flaccidity) seen in silkworm larvae suffering from dysentery.

Flacherie viral
An infectious flacherie of silkworm larvae caused by a small non-occluded virus.

Flagellae
Plural of flagellum.

Flagellate
Having one or more flagella.

Flagellosis
Infection with a flagellate protozoan.

Flagellum
A whip-like filament projecting from a bacterium or zoospore and functioning as an organ of locomotion. Also called a cilium.

Flagging
The loss of rigidity and drooping of leaves and tender shoots preceding the wilting of a plant.

Flag stage
(Also knee stage in onions). The early post-emergence stage of onion seedlings between the crook stage and the emergence of the first true leaf. The bent tip of the seed leaf resembles a flag attached to a staff. Also used to designate the stage of development in cereals and other grasses at which the sheath and leaf have been produced.

Flame gun: Flame thrower
Device producing tongue of flame, used to kill weeds and brushwood.

Flammable
Readily ignitable.

Flammable liquid
A liquid having a flash point of 21°C or more but less that 55°C as determined by a closed cup method.

Flash point
The lowest temperature at which a material forms a flammable vapour/air mixture under standard conditions.

Flat storage
Mainly bag type storage, but could be bulk storage.

Flavonoid
Any number of compounds, including plant pigments, related to or similar in chemical structure to flavone C15H10O2.

Flavoprotein
A protein containing a derivative of riboflavin, which acts as an electron carrier in the electron-transport system.

Fleck
A minute spot.

Flesh fly
Any member of the dipteran family Sacrophagidae.

Flexible budget
A budget which is designed to change in accordance with the actual level of activity achieved.

Flexuous
Full of bends and curves.

Flint
A maize (Zea mays indurata) having usually rounded kernels with a hard outer layer.

Flocculation
Joining together of particles in suspension.

Flo-dust (GP)
Special form of dustable powder for pneumatic application in greenhouses.

Floor spray
See spray vi.

Floret
Lemma and palea with the enclosed flower, they may be bisexual and perfect, or unisexual and male or female or infertile. Individual small flower, as in grasses or composites.

Flow
The rate of transfer of material between compartments or state variables.

Flow diagram
The diagrammatic representation, usually with conventional symbols, of the structure of a system in terms of physical and information flows between compartments.

Flowability
Property of flowing possessed by dusts, colloids or liquids.

Flowable
A type of pesticide formulation in which a very finely divided pesticide is mixed in a liquid carrier.

Flowable concentrate for seed treatment
A stable suspension for application to the seed either directly or after dilution.

Flowable powders
Contain the finely divided herbicide mixed with surface active agents and a small volume of water. Like wettable powders they are diluted with water before use.

Fluorescein
A fluorescent substance adsorbed to antibodies in order to facilitate their detection and location on a tissue.

Fluorescent
Having the ability to emit light of a certain wavelength when activated by light of another wavelength.

Fluorescent antibody
Immunoglobulin molecule which has been coupled with a fluorescent dye so that it exhibits the property of fluorescence.

Fluorescent tracer
Fluorescent material added to spray to aid assessment of deposit on plant material.

Flux
A flow of matter or energy of which direction, rate and density can be determined.

Flux density
The amount of energy or matter passing through a unit area perpendicular to the stream per unit time.

Flying herd
A dairy herd where calves are not reared, replacement down-calving heifers may be brought in. Most commonly met where land values and milk prices are high so that the price of milk does not justify its being fed to calves, and other uses of the land pay better than rearing heifers. An example of stratification.

Foaming agent
A chemical that causes a pesticide preparation to produce a thick foam, which aids in reducing drift.

Foci
A small group of cells occurring e.g. in the liver, distinguishable, in appearance or histochemically, from the surrounding tissue. They are indicative of an early stage of a lesion which may lead to the formation of neoplastic nodules or hepatocellular carcinomas.

Focus
The site of local concentration of infection of infestation from which secondary spread may occur.

Fodder
Coarse grasses, such as maize and sorghum, which are harvested whole and cured in an erect position for animal feed.

Foetus
The young of mammals when fully developed in the womb. In human beings, this stage is reached after about 3 months of pregnancy. Prior to this, the developing mammal is at the embryo stage.

Fog treatment
The application of a pesticide as a fine mist for the control of pests.

Foliage-acting
A herbicide which is active when applied to foliage.

Foliage applied herbicides
Compounds penetrate the outer waxy cuticle and are absorbed into the leaf tissue, where they may or may not be translocated basipetally in the phloem.

Foliar spray fertilisers
Nutrients sprayed in solution on to leaves.

Foliar application
Application of a pesticide to the leaves or foliage or plants.

Fomite
An article or substance, other than food, which can harbour and carry micro-organisms and transmit them from one animal to another, thus disseminating a disease.

Food
Those commodities which people normally eat: the weight of wholesome edible material, measured on a moisture-free basis, that would normally be consumed by humans. Inedible portions of the crop, such as stalks, hulls and leaves are not food. A useful but arbitrary distinction is often made between 'food', consumed by man, and 'feed', consumed by or fed to animals.

Food chain
Sequence of species within a community, each member of which serves as food for the species next higher in the chain e.g. plants, herbivores, carnivores.

Food infection
Illness arising from ingestion of food containing pathogenic organisms such as some salmonella which grow in the gastrointestinal tract.

Food loss
Any change in the availability, edibility, wholesomeness or quality of food that reduces its value to humans.

Food poisoning
Illness arising from ingestion of food containing toxins from the growth of organisms such as some staphylococci or clostridia.

Food web
A complex of branching, joining or diverging food chains that connect together the various populations in an ecosystem.

Foot rot
Rotting involving the lower part of the stem-root axis, but not the distal parts of the roots.

Forage
Vegetable matter, fresh or preserved, utilised as feed for animals.

Forb
A non-grass-like herb of the range. Small grass-like plant.

Forecasting
Method for extrapolating the future from analysis of available data of the past. Most often applied in statistical analysis of time series.

Foreign matter
Other things, such as stones, sand, chaff, straw or other seeds mixed with the crop product e.g. rice grain.

Form
A subdivision within a species or variety.

Formal reaction
An equation describing an electrochemical reaction in which electrons are included as reactants.

Forma specialis
Special form: a biotype (or group of biotypes) of a species of pathogen that differs from others in the ability to infect selected genera or species of susceptible plants. (usually abbreviated as f. sp.). A subspecific taxon usually denoting the host genus of which the organism is a parasite e.g. tritici to denote wheat in Puccinia graminis f. sp. tritici.

Formamidine insecticide
An insecticide with a mode of action that is highly effective against insect eggs and mites.

Formulant
Any substance other than technical material(s) incorporated in a formulation.

Formula pricing
A pricing method based on a cost calculation plus a percentage for profit.

Formulation
Way in which basic pesticide is prepared and sold for use. It contains the active ingredient(s) includes dusts, baits, fumigants, aerosols, granules. Emulsifiable concentrates, wettable powders and suspension concentrates.

Forrester diagram
Model compartment diagram including information about factors controlling flows.

Fossorial
Modified for digging; in the habit of digging or burrowing.

Foster-mother
A cow used to suckle one or more calves in addition to her own.

Foundation seed
The progeny of breeder's seed and the first major increase of seed of an improved strain or variety, handled so as to maintain its superior genetic qualities.

Fractile
Let _ be between 0 and 1. In a set of observations of a variable the _ fractile is the number for a fraction _ of the observations is less than this number. The fraction is often given in percent; the term percentile may then be used.

Fractional factorial design
An experiment design in which parameters are studied at several levels with only a fraction of the possible parameter-level combinations included in the experiment.

Fractional sterilisation
A process in which some material is made sterile by several brief applications of heat over a period of time.

Frame
A list of sampling units.

Frame shift
Since the genetic code is read three bases at a time, if reading begins at either the second or third base of a codon, a faulty product usually results. This is called a frame shift (the reading frame refers to the pattern of reading).

Frame shift mutation
A change in the structure of DNA such that the transcription of genetic information into RNA is completely altered because the start point for reading has been altered i.e. the reading frame has been altered.

Frass
Refuse and excrement, left by insects larvae particularly borers.

Free energy
Energy available to do useful work.

Free-living
Growing outside of and not directly dependent on other organisms e.g. a pathogen living in the soil, outside of its host.

Freeze-drying
A technique used in the preservation of living material, whereby water is removed under vacuum while the tissue remains frozen.

Frequency distribution
A specification of the way in which the frequencies of members of a population are distributed according to the values they exhibit.

Freund's incomplete adjuvant
A substance containing an emulsifier and mineral oil, which is mixed with a virus before it is injected into the muscles of an animal to produce anti-serum. The adjuvant allows slow release of the virus following injection.

Friability
The tendency of a granule to crumble, breaking down into smaller particles.

Friable
Crumbly; a desirable condition in a soil.

Friction polisher
Type of whitener using the friction between the rice grains to remove the bran layer.

Friedman test
A non-parametric test to compare t > 2 treatments when the randomised block design has been used. The data are ranked within each block, and the rank sums for each of the t treatments are used in the Friedman test statistic, X2.

Fringe benefits
Personal compensation for work done, usually given in the form of insurance, paid leave, housing, transport or some other perquisite.

Fructification
Spore production by fungi; or, a structure in or on which spores are formed. Also a fruiting body.

Fruit
The developed ripened ovary of a seed plant, e.g. pea pod, nut, tomato. The ripened ovary with adnate parts.

Fruit-bud stages
i) breaking. Stage at which scales of fruit tree blossom buds begin to separate at bud apex
ii) burst. Stage at which fruit tree blossom buds show separated leaf tips emerging from bud apex
iii) cot-split. Stage shortly after petal-fall in plum when dead calyx splits to reveal small fruitlet
iv) fruitlet. Stage in some fruit development 2-3 weeks after petal-fall v) grape. Blossom-bud stage in black currants at which unopened flowers are revealed in tight clusters
vi) green - flower (green - cluster). Blossom-bud stage of tree fruits at which unopened flower buds are tightly clustered within a rosette of opened leaves
vii) mouse-ear. Stage of development of apple fruit bud when partially expanded rosette leaves protrude about 5 mm from bud apex
viii) petal-fall. Stage of tree fruits at which 80% of petals have fallen
ix) pink-bud. Stage at which blossom-buds of apple have well-developed and coloured petals, but flowers are still unopened
x) white-bud. Blossom stage in pears when petals show boldly but flowers are still unopened

Fruiting body
A complex structure that bears fungal spores, e.g. sporangia, coremia, sporodochia, acervuli, pycinidia, apothecia, perithecia.

Fugacity
(1) The tendency for a substance to transfer from one environmental medium to another (2) Analogous to chemical potential as it pertains to the tendency of a chemical to escape from a phase e.g. from water.

Full-coverage spray
Spray applied thoroughly over a crop to the point of runoff or drip.

Full-sib
Having both parents in common.

Fumigant
Liquid or solid chemical that forms vapours that kill organisms. Particularly used in the treatment of areas difficult to penetrate with sprays or other pesticidal formulations, e.g. soils.

Fumigation
The application of a fumigant for disinfestation of an area.

Functional group
A group of species that are assumed in a model to function in a similar fashion by having the same parameter values for process equations. These are lumped together in the model as a single entity.

Functional response
Term used to describe the relationship between the number of prey attacked per parasitoid (or predator) at different prey densities and the numerical response between predator numbers and prey density.

Fundatrice
A viviparous parthenogenetic female aphid produced on a primary host plant from an overwintering fertilised egg.

Fundatrigeniae
Progeny of the fundatrix; often applied to all spring generations following the fundatrix of a heteroecious aphid on its primary host.

Fundatrix
Parthogenetic females which produce sexual females; in heteroecious aphids, the return migrants to the primary host in autumn.

Fungi
All non-chlorophyll-bearing thallophytes (i.e. all non-chlorophyll-bearing plants of a lower order than mosses and liverworts) that often show mycelial, spreading growth e.g., rusts, mildews, moulds and yeasts.

Fungicidal
Killing fungal spores of mycelium.

Fungicide
Chemical or physical agent that kills or inhibits development of fungus spores or mycelium (or when used in a broad sense bacteria). The term 'fungicide' includes all preparations intended for preventing, destroying, repelling or mitigating any fungi. Fungi includes all such organisms as rusts, smuts, mildews, moulds, yeasts, viruses and bacteria, except those on or in living man and other animals.

Fungicide resistance
A decrease in sensitivity to a fungicide due to selection or mutation following exposure o the compound.

Fungi Imperfecti
A form class erected to contain those fungi whose sexual reproduction is unknown.

Fungistasis
The prevention of fungal growth; the effect is reversible, if the inhibitor is removed or diluted, growth is resumed.

Fungistatic
Able to inhibit germination of fungus spores or development of mycelium without causing death of fungus.

Furrow application
Placement of pesticides with seed in furrow at time of sowing.

Futile cycling
The generation of superoxide of peroxide anions through the cyclic activation of molecular oxygen by the cytochroms P-450 when these combine with a difficulty-oxygenated substrate (e.g. phenobaritone) and are reduced by cytochrome P-450 reductase and NADPH. Mixed-function oxidation by the cytochromes P-450 generally reduces molecular oxygen to give the oxygenated chemical substrate plus water; in futile cycling molecular oxygen is reduced to super-oxide or peroxide and the chemical substrate is left unchanged.