Glossary of forest protection


[1] Diagnosing Injury to Eastern Forest Trees. The Pennsylvania State University, Pennsylvania, 1987. 122 p.

A - B - C - D - E - F - G - H - I - L - M - N - O - P - R - S - T - U - W - Z


ABDOMEN - The third or posterior major division of the insect body; consists normally of nine or ten apparent segments; bears no functional legs in the adult stage, but may bear prolegs or false legs in the larval stage.[1] Fin. Swe.

ABIOTIC PATHOGEN - A nonliving, disease-causing entity, e.g., drought, salt, air pollutants.[1] Fin. Swe.

ACUTE INJURY - Injury, usually involving necrosis, which develops within several hours to a few days after a high dose exposure to a pollutant; expressed as fleck, scorch, bifacial necrosis, etc.[1] Fin. Swe.

AECIAL STAGE (aecium) - A spore stage of the rust fungi; a cuplike structure bearing aeciospores.[1] Fin. Swe.

ALTERNATE HOST - One of two taxonomically different hosts required by a heteroecious rust fungus to complete its cycle; also applies to some insects.[1] Fin. Swe.

ANTERIOR - In front; before; opposite of posterior.[1] Fin. Swe.

ANTHOCYANOSIS - Presence of abnormal red-purple coloration in foliage.[1]

ASEXUAL STAGE - Vegetative; without sexual organs or spores.[1] Fin. Swe.

AUTOECIOUS - Completing entire life cycle on one host; especially applied to the rust fungi.[1] Fin. Swe.


BANDING - A foliar symptom characterized by a limited zone of necrotic or discolored tissue traversing the leaf, e.g., the band of tissue on a pine needle injured by SO2 or 03.[1]

BASIDIAL STAGE (basidium)- A spore stage of the rust fungi; a specialized structure in the Basidiomycetes bearing basidiospores.[1] Fin. Swe.

BASIDIOCARPS - Sexual fruiting structure in the Basidiomycetes; conks, sporophore, mushrooms, etc.[1] Fin. Swe.

BIFACIAL NECROSIS - Death of plant tissues, extending from the upper to the lower leaf surface.[1]

BIOINDICATOR SPECIES - Species, varieties, or cultivars sufficiently sensitive to a specific pollutant to be useful as indicators for the presence of that pollutant.[1] Fin. Swe.

BIOTIC PATHOGEN - A living organism capable of inciting disease, e.g., fungi, bacteria, viruses, etc.[1] Fin. Swe.

BLEACHING - Loss of normal color, tending toward white, cream, or tan coloration.[1] Fin. Swe.

BLIGHT - A common term for several different diseases; usually applied to those where leaf damage is sudden and severe.[1] Fin. Swe.

BRONZING - A golden brown discoloration that usually appears on the lower surface of leaves and is often an advanced stage of the silvering or glazing typical of injury by PAN and other oxidants; brown coloration on needles due to spider mite infestation.[1] Fin. Swe.


CALLUS TISSUE - A protective tissue of thin-walled cells developed on wound surfaces, often beginning at the edges of a wound.[1] Fin. Swe.

CANKER - A plant disease symptom characterized by a sharply defined necrosis of cortical tissue, often sunken below bark surface.[1] Fin. Swe.

CHEWING INSECTS - Insects that consume all tissues of leaves or portions of leaves, using robust mandibles for chewing.[1] Fin.

CHLOROSIS - Yellowing of plant tissue due to failure of chlorophyll synthesis or to chlorophyll destruction.[1] Fin. Swe.

CHLOROTIC DWARF - An abiotic disease of Pinus strobus characterized by reduced growth, chlorosis and mottling of the needles, and premature abscission of all but current needles.[1]

CHRONIC INJURY - Injury which develops after long-term or repeated low dose exposure to an air pollutant expressed as chlorosis, bronzing, premature senescence, reduced growth, etc.[1] Fin. Swe.

CLONAL LINES - A group of plants originating from buds or cuttings from the same individual.[1]

CONK - The fruiting structure of a wood-rotting fungus, especially of one of the Polyporaceae.[1] Fin. Swe.

COCOON - A covering, composed partly or wholly of silk or other sticky fiber, spun or constructed by many larvae as a protection for the pupal stage.[1] Fin. Swe.

CORNICLES - The posterior dorsal erect or semi-erect tubules of aphids which secrete a waxy defensive liquid to protect the insect against enemies; short, blunt horns or rounded projections occurring on the abdomen.[1]

CRAWLER - The first instar motile nymphal stage of scale insects and mealybugs, which moves to a new feeding site before settling down to a sessile existence for the rest of its developmental life.[1]

CRINKLING - Bending or twisting of foliage without breaking; wrinkling.[1] Fin. Swe.

CRYPTIC - Hidden or concealed.[1] Fin. Swe.


DEFOLIATOR - Any chewing insect that consumes the leaves or needles of plants.[1] Fin. Swe.

DELIQUESCENT - To ramify into fine divisions, such as abnormal numbers of buds, twigs, branches, or leaves, e.g., witches' broom development.[1] Fin. Swe.

DORSAL - Of or belonging to the upper surface; top.[1] Fin. Swe.

DORSOVENTRAL - From top to bottom; from the upper surface to the lower surface.[1]

DORSUM - The upper surface; top.[1] Fin. Swe.

DOSE - A measured concentration of a toxicant for a known duration of time (concentration per unit time).[1]


EGG GALLERY - A long, narrow tunnel along the sides of which eggs are deposited in small niches; the pattern of construction is often diagnostic of a particular species of insect.[1] Fin. Swe.

EGG MASS - Cluster of eggs, usually in a matrix of body hairs or wing scales from the female adult and/or a mucilaginous cementing secretion.[1]

ELYTRA - The anterior leathery or chitinous wings of beetles and leafhoppers; serve as coverings to the hind wings and commonly meet at rest in a straight line down the middle of the dorsum.[1] Fin. Swe.

ENGRAVER - Beetle which feeds in the phloem-cambium region of woody plants, often scoring or engraving adjacent sapwood tissues.[1]

EPICORMIC BRANCHING - Branches arising from buds in bark along mainstem, most commonly occurring in trees under crown stress; also called watersprouts.[1] Fin. Swe.

EPIDEMIC - A change, usually a sudden increase, in a disease within a population.[1] Fin. Swe.


FOREWINGS - Front pair of wings.[1] Fin. Swe.

FLECK - White to tan necrotic lesions up to a few millimeters in length or diameter, usually confined to the upper surface of leaves.[1] Fin. Swe.

FRASS - Solid larval insect excrement; mixed with wood fragments in woodboring or bark-boring insects.[1] Fin. Swe.

FRUITING BODY - A specialized structure, often macroscopic, on or in which spores are produced.[1] Fin. Swe.

FUMIGATION - The natural or controlled exposure of plants to toxic gases or volatile substances.[1] Fin. Swe.


GALL" - A swelling or outgrowth of tissue induced by a pathogen or insect on a slant.[1] Fin. Swe.

GENERATION - The successive developmental stages from reproduction to reproduction, e.g., egg, larva, pupa, adult.[1] Fin. Swe.

GIRDLING - Destruction of tissue in a ring around a twig, branch, or stem.[1] Fin. Swe.

GOUT - Formation of swellings at nodes or at the base of buds.[1]

GREGARIOUS - Living in groups or communities.[1] Fin. Swe.

GRUB - An insect larva; a term loosely applied, usually to larvae of Coleoptera; larva is thick-bodied with well-developed thoracic legs but no abdominal prolegs.[1] Fin. Swe.


HETEROECIOUS - Requiring two taxonomically different hosts to be able to complete the entire life cycle, as in the rust fungi.[1] Fin. Swe.

HONEYDEW - A sweetish excretion produced through the anus by certain insects, notably aphids and scale insects.[1] Fin. Swe.

HOST - A living organism serving as a food source for a parasite.[1] Fin. Swe.

HYSTEROTHECIUM - A sexual fruiting structure of the Ascomycete fungi, usually football-shaped or elongate in appearance and occurring on infected needles.[1] Fin. Swe.


INSTAR - The insect itself during the time between molts in the larva or nymph, numbered to designate the various periods; i.e., the first instar is the insect between the egg and first molt.[1]

INTERVEINAL - Between veins.[1] Fin. Swe.

INTRAVEINAL - Associated along or within veins.[1] Fin. Swe.


LARVA(plural = larvae) - The immature instars, between the egg and pupal stages, in an insect having a complete metamorphosis (egg, larva, pupa, adult). Larvae feed and grow but cannot fly, nor can they reproduce.[1] Fin. Swe.

LESION - A wound; a well-marked, but limited, diseased area; a break or rupture through a tissue, especially a surface tissue.[1] Fin. Swe.

LOOPER - A caterpillar in which some or all of the middle abdominal prolegs are wanting and which moves by placing the posterior part of the abdomen next to the thorax, forming a loop of the intervening segments, then extending the anterior part of the body forward.[1] Fin. Swe.


MIDDORSAL - In the middle of the upper side or dorsum.[1]

MIMICKING SYMPTOMS - Symptoms similar to those caused by pollutants but induced by other abiotic or biotic causal agents.[1]

MINER - The larval stage of an insect which makes galleries or burrows between the upper and lower surfaces of leaf tissue.[1] Fin. Swe.

MITE(S) - Small, often minute, arthropods in the order Acarina of the class Arachnida, which includes spiders, scorpions, and related forms. Mites have four pairs of legs vs. three pairs in insects.[1] Fin. Swe.

MOLT - To cast off the outgrown skin or cuticle in the process of insect development; changing from one instar to the next.[1] Fin. Swe.

MOTTLE - Irregular, diffuse patterns of chlorotic areas interspersed with normal green leaf tissue.[1] Fin. Swe.

MOSAIC - A diseased condition where different portions of a leaf vary in amounts of chlorophyll, thus giving the leaf a mottled appearance; usually caused by viruses.[1] Fin. Swe.

MYCELIUM - A mass or aggregate of hyphae; vegetative stage of fungi.[1] Fin. Swe.


NAKED - Larva devoid of body hairs or setae; pupa not enclosed in a cocoon or other covering.[1]

NECROSIS - Death.[1] Fin. Swe.

NYMPH - The immature stage of insects, following hatching, which does not have a pupal stage, i.e., incomplete metamorphosis (egg, nymph, adult). Late instar nymphs may have nonfunctional rudimentary wings and/or genitalia.[1] Fin. Swe.


OVIPOSITION - The act of depositing the eggs.[1] Fin. Swe.

OVIPOSITOR - The egg-laying apparatus; the extended genitalia of a female insect.[1] Fin. Swe.


PARASITE - An organism which lives on or in another living organism and obtains part or all of its nutrients from that other living organism.[1] Fin. Swe.

PATHOGEN - Any agent of the environment capable of inciting disease.[1] Fin. Swe.

PERITHECIUM" - A sexual fruiting structure of the Ascomycetes with an opening called the ostiole at or near its top.[1] Fin. Swe.

POSTERIOR - Hind or hindmost; opposite of anterior.[1] Fin. Swe.

PREDISPOSITION - The weakening of an organism by some factor(s) of either the physical or biotic environment so as to render the organism more susceptible to a pathogen.[1] Fin. Swe.

PROLEG - Any process or appendage that serves the purpose of a leg; specifically, the fleshy, unjointed, ventral abdominal projections of caterpillars and certain sawfly larvae.[1] Fin. Swe.

PUPA - The resting, inactive, nonfeeding instar in all holometabolous insects; the stage intermediate between the larva and the adult.[1] Fin. Swe.

PYCNIAL STAGE (pycnium) - A flaskshaped spore stage of the rust fungi; oozes out spores in a sticky matrix.[1]

PYCNIDIUM - An open-pored, flaskshaped fruiting structure in which asexual spores called conidia are produced.[1] Fin. Swe.


RASPING - A type of feeding by insects which rub or grate the leaf surfaces with their mouthparts to obtain particles for consumption.[1] Fin. Swe.

RESINOSIS - Resin flow through bark or from wounds or cankers on conifers.[1] Fin. Swe.

RHIZOMORPH - A thread- or cordlike fungal structure made up of hyphae.[1] Fin. Swe.

RINGSHAKE - Peripheral cracks in woody tissues of stems. The pattern of damage is concentric with the annual rings.[1] Fin. Swe.

RINGSPOT - A circular area of chlorosis with a green center.[1]


SAPROPHYTE - An organism living on dead organic matter.[1] Fin. Swe.

SCORCH - Appearing as if tissues were burned by heat; usually affecting marginal portions of leaves.[1] Fin. Swe.

SENESCENCE - Aging of tissues; growing old.[1] Fin. Swe.

SESSILE - Attached or fastened; incapable of moving from place to place.[1] Fin.

SETA (plural = setae) - Slender, hairlike or bristly projections arising from the epidermal layer on any part of the body of an insect.[1] Fin. Swe.

SEXUAL STAGE - Reproductive stage of the life cycle of an organism.[1] Fin. Swe.

SHOTHOLES - Small holes in a leaf caused by feeding activity and giving the appearance of injury via a shotgun.[1]

SIGN - The actual presence of the causal organism in association with the disease symptoms.[1]

SKELETONIZER(S) - Insects which consume leaf tissue, often from the lower side of the leaf, leaving the upper epidermis and vascular tissues intact.[1]

SPORE - A specialized structure consisting of one or few cells and serving any or all of the following three functions: (i) reproduction, (ii) dissemination. (iii) survival.[1] Fin. Swe.

SPOROPHORE - A spore-producing or supporting structure.[1] Fin. Swe.

STADIUM (plural = stadia) - The period of time between two successive molts.[1] Fin. Swe.

STAGE - One of the successive principal divisions in the life cycle of an insect, e.g., egg, nymph, larva, prepupa, pupa, adult.[1] Fin. Swe.

STAGHEAD - Death of limbs and main branches of a tree in the upper crown, giving the appearance of antlers.[1] Fin. Swe.

STIPPLE - Pigmented spots up to a few millimeters in diameter, often on the upper surface of leaves.[1]

STYLET - A small, stiff, needlelike tube inserted into a food source to obtain liquid food.[1]

SUCKING INSECTS - Insects that insert their mouthparts into plant tissues and withdraw nutrients and fluids through stylets.[1] Fin.

SUSCEPT - Any organism that can be attacked by a biotic pathogen.[1]

SYMPTOM - Visible or measurable manifestation that an organism is diseased; a change in the organism itself.[1] Fin. Swe.


TELIAL STAGE (telium) - A stage of the rust fungi; a fruiting structure usually appearing as fine, hairlike projections from lower surfaces of infected leaves.[1] Fin. Swe.

THORACIC - Belonging or attached to the thorax.[1] Fin.

THORAX - The body region behind the head, which bears wings and true (jointed) legs if present.[1] Fin. Swe.

TUFT - Bunching of twigs or needles.[1] Fin. Swe.

TYLOSIS - Outgrowth of a cell membrane from a ray or axial parenchyma cell through a pit in a xylem vessel wall into the vessel, partially or completely blocking the lumen of the vessel.[1]


UREDIAL STAGE (uredium) - A stage of the rust fungi; a fruiting structure usually appearing as a pustule bearing the repeating spore stage that leads to disease increase. Fin. Swe.


WATER-SOAKED - A dull green coloration of diseased tissues due to membrane leaking of cellular contents into intercellular spaces.[1] Fin. Swe.

WILT - A common symptom of disease due to a loss of turgor and resulting in subsequent drooping and collapse of the foliage or succulent tissues.[1] Fin. Swe.

WITCHES' BROOM - A massed proliferation of the branches of a woody plant.[1] Fin. Swe.


ZONE LINE - Narrow brown or black lines in decayed or decaying wood.[1]

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