IPM for Christmas Trees: Glossary

Common terms used in Integrated Pest Management (IPM) and Christmas trees.
IPM for Christmas Trees: Glossary - Articles


Christmas tree plantation. Courtesy Lynn Kime.

Adelgid: members of the family Phylloxeridae (Homoptera), including gall, pine, and woolly adelgids, that are closely related to aphids but only found feeding on conifers, some forming galls

Aecium (aecia, pl.): a cup-shaped fruiting body of the rust fungi that produces aeciospores

Aeciospores: rust fungi spores produced within aecia by infection

Bacterium (bacteria, pl.): a single-celled, microscopic, plantlike organism that lacks chlorophyll and reproduces by fission

Basidiospore: an infectious spore produced by some rust fungi

Bloom (glaucous bloom): the blue color of conifers (e.g., Colorado blue spruce) that is removed when sprayed with horticultural spray oil or insecticidal soap

Brood: individuals hatching from eggs laid by one mother around the same time (including maturation later in life)

Callow adults: condition of an adult shortly after emerging from the pupal case where its cuticle is not fully hardened or mature in color

Cambium: a layer of actively dividing cells lying between the xylem and phloem in the stems and roots of vascular plants

Candle: the growing, terminal shoot of certain conifers, particularly pines

Canker: a disease of the bark and cambium that causes the tissue to become sunken or swollen

Chlorosis: yellowing of normally green foliage or tissue due to chlorophyll destruction or failure of chlorophyll functions; often a symptom of some mineral deficiency, extremely reduced light, root or stem girdling, pests, or viral infection

Chlorotic (in terms of growth and spots): spots or splotching of normally green foliage due to a problem with the chlorophyll; often caused by insect feeding or disease

Chrysalis: the pupal stage of butterflies; also known as the resting time between the larval and nymphal stages of mites

Conidia (conidium, sing.): an asexual fungus spore

Conidiophore: a specialized hypha bearing one or more conidia

Contact dermatitis: a skin rash caused by an allergic reaction to something coming in contact with the skin (e.g., irritating hairs of gypsy moth caterpillar)

Cull: removal of plants suspected to be infected of a disease, thus reducing the possibility of a spread of infection to plants not already affected

Cuticle: with insects, the noncellular, thin, waxy outer layer of the body wall (exoskeleton) made up of wax and chitin; with plants, it is a thin, continuously waterproofed, noncellular film on the external surface that tends to prevent desiccation and repels external water

Cutin: the waxy substance comprising the inner layer of the cuticle; waterproof mixture of waxes, fatty acids, soaps, higher alcohols, and resinous materials forming the chief ingredient of the cuticle of many plants

Desiccate (desiccation): a loss of internal moisture content necessary to maintain growth, rigidity (helps keep the plant up), or survival; also known as dehydration or drying

Epidermis: with insects, the cellular layer of the body wall that secretes the cuticle; with plants, the outermost layer of cells occurring on all the plant parts

Epithelial cell (epithelial cells, pl.): layer of cells lining the resin duct

Excelsior-like strands: fine-curled wood shavings that result from insect feeding in the wood

Filament: a slender, threadlike structure

Fissure: a narrow, longitudinal opening (slit)

Fruiting body: a fungal organ specializing in the production of spores (e.g., aecium, apothecia, pycnidium, tilia)

Gallery (galleries, pl.): a tunnel or chamber made by larvae of wood-boring insects and composed of silk and fecal waste; usually made by bark beetles (often forming characteristic galleries that can be used in identification) and miners and shoot, timber, and wood borers

Host-specific: the degree to which an organism is limited to a specific type of host

Hypha (hyphae, pl.): one of the filaments of fungal mycelium

Inoculum: a disease-causing propagule that can cause infection when brought into contact with the host

Insect growth regulator (IGR): a pesticide built to imitate insect hormones that control molting and the development of some insect systems, affecting the change from immature to adult; in most cases, prevents the insect from becoming a sexually mature adult and may result in death

Lesion: a localized area of discolored, diseased tissue resulting from an injury or wound

Mottle (mottling): a spot or blotch of indistinct light and dark areas usually found on the needles

Mycelia (mycelium, sing.): the threadlike, vegetative part of fungi; a mass of hyphae

Necrotic: discolored or dead

Niche (niches, pl.): a recessed compartment within a gallery where a female lays an egg

Nuptial chamber: a large chamber created by male bark beetles used for mating with multiple females

Oviposition: laying or depositing of eggs

Ovipositor: the female insect’s egg-laying apparatus (external genitalia)

Parasitoids: sometimes referred to as parasites and predators, these organisms feed in or on another living organism (host) over a long time span, consuming most to all of its tissues and resulting in death of the organism; behavior is intermediate between parasitism and predation

Parthenogenesis (parthenogenetically): development of an egg without being fertilized

Pathogen: a parasitic organism completely capable of causing disease

Phloem: the layer of cells just inside bark of plants that conduct food from leaves to the stem and roots; different from xylem by the absence of thickened cells and the presence of cells containing sieve-like areas

Proleg (prolegs, pl.): a fleshy, abdominal leg of certain insect larvae

Pupate: larva transforming into a pupa

Pycnidia (pycnidium, sing.): specialized, spherical, fungal fruiting bodies of rust fungi that produce infectious spores

Resin duct: a tube or duct lined with epithelial cells in a woody stem or leaf, especially in conifers, that secretes resin (e.g., sap)

Rhizome (rhizomes, pl.): a horizontal stem of a plant typically located underground that sends out roots and shoots

Rhizomorph (rhizomorphs, pl.): root-like structure of a fungus consisting of an aggregation of parallel hyphae

Rosette: cluster of leaves in crowded circles or spirals rising up from the stem base (e.g., dandelion)

Sclerotia (sclerotium, sing.): firm, often rounded masses of hyphae that serve as resting bodies and are resistant to unfavorable conditions

Senescence: life phase of part of or a whole plant that involves decreased ability to repair damage, decline, or other factors that eventually lead to natural death

Sessile: attached or fastened; incapable of moving from place to place

Spore: single- or multiple-celled reproductive unit of fungi; each is capable of germinating and reproducing the organism (fungi)

Sporulation: to produce or release spores

Stem mother: a female aphid that produces live, identical aphids just before or as buds break

Stippled: small dead spots on the leaves caused by mites’ and insects’ piercing-sucking mouthparts—specifically, a loss of sap and the toxic effect of saliva on the leaf tissue

Stomata: pores in plant leaves that control gas exchange (carbon dioxide and oxygen) and
transpiration of a plant

Xylem: plant tissue (of trees and woody shrubs) consisting of various cell types that transport water and dissolved substances to the leaves; the main water-conducting tissue and chief supporting system composed of wood cells responsible for conduction, food transport, storage, and support