Vocabulary
Abiotic: Relating to nonliving agents, including physical and environmental factors. Examples: precipitation, temperature, mechanical, and chemical influences.
Active ingredient: The ingredient in a pesticide product that controls the target pest.
Alkaline: Having basic (non-acidic) properties; a pH greater than 7.
Alternate leaf arrangement: Only a single leaf is attached at each stem node.
Alternate host: One of two kinds of plants on which a pathogenic fungus must develop to complete its life cycle. Example: cedar-apple rust.
Annual: A plant that normally completes its life cycle of seed germination, vegetative growth, reproduction, and death in a single year.
Appressed: Lying flat or pressed closely against something.
Arthropod: A group of animals characterized by having an exoskeleton made of chitin, bilateral symmetry, and segmented appendages.
Asexual: A type of reproduction in the absence of males.
Balled and burlapped: Nursery trees or shrubs that have been dug with soil surrounding the roots and wrapped with material.
Bare root: Pertaining to tree seedlings raised in open fields and lifted from the soil prior to transplanting.
Beneficial organism: An individual plant, animal, or microorganism that can provide a benefit to an aspect of plant growth, pollination, or pest management.
Biological control: The action of parasites, predators, or pathogens in maintaining another organism’s population density at a lower average level than would occur in their absence.
Biotic: Relating to living organisms. Examples: pathogens (fungi, bacteria), insects, mites, and vertebrates.
Blight: Sudden, severe withering of leaves, flowers, shoots or fruit.
Broadleaf: Plants with leaves that have a flat, relatively wide surface compared to those with needle-like leaves.
Broad-spectrum: Insecticides that lack selectivity to a particular insect.
Canker: Dead, discolored, often sunken area (lesion) on a root, trunk, stem, or branch.
Candle: The new growth on pine and spruce trees.
Catkin: A tassel-like spike of closely clustered, small, unisexual flowers without petals. Examples: birch and willow have catkins.
Chlorosis: Yellowing of leaves, veins, or areas of leaves between the veins.
Complete metamorphosis: An insect’s change in form during development that involves egg, larval, pupal, and adult stages.
Compound leaf: A leaf divided into discrete leaflets.
Conifer: Cone-bearing plant.
Contact insecticide: A pesticide that is intended to directly contact the insect and that is absorbed through the exterior of the insect.
Corymb: A flat-topped flower cluster.
Crawlers: Scale insects in their active stage.
Crown: The part of the tree where the trunk or main stem joins the roots and the upper canopy.
Deciduous: Trees or shrubs that lose their leaves every year.
Dioecious: Male and female flowers on separate plants; both must be present for the female to produce fruit.
Disease cycle: Stages of disease development and the effect on the host.
Dormant oil: A horticultural oil that is applied prior to bud break to target overwintering insects.
Drupe: Fleshy fruit with one or more stony seeds.
Evergreen: Plants that retain most of their leaves throughout the year.
Exclusion: The use of barriers to separate pests and diseases from susceptible plants.
Exit holes: The area of a tree or branch from where an adult wood-boring insect emerges.
Frass: Excrement produced by insects and other arthropods.
Fungus: A multicellular organism lacking chlorophyll, such as mold, mildew, smut, or rust.
Gall: Swelling or outgrowth of plant tissue, often formed in response to the action of a pathogen or other pest.
Galleries: Etchings in the wood formed from the larvae of wood-boring beetle feeding and activity.
Girdling: Injury to the bark, cambium, and sapwood that completely encircles the trunk or branch of a tree.
Gummosis: The reaction of a tree to outside stimuli like weather, pathogens, or insects, resulting in the discharge of a gummy substance.
Herbicide: A pesticide designed to control or kill plants.
Honeydew: A waste product excreted from sap-sucking insects, such as aphids, mealybugs, whiteflies, and soft scales.
Horticultural oil: Highly-refined oil used to control soft-bodied insects and insect eggs in the summer and the dormant season.
Host: A plant or animal that provides nourishment for another organism.
Inflorescence: The arrangement of flowers on a plant.
Lanceolate: Leaf shape that is longer than wide, with the widest point below the middle of the leaf.
Larvae: The immature stage of an insect that goes through complete metamorphosis.
Least toxic: Pest management products and techniques that have low or no toxicity to humans or are formulated and/or applied in a manner that minimizes exposure to humans and other nontarget organisms.
Lenticel: Pores in the bark of woody plants that allow gases to pass between the outside atmosphere and the interior of the plant.
Microorganism: An organism of microscopic size, such as a bacterium, virus, or fungus.
Monitoring (scouting): Regular collection of information related to the activity, growth, development, and abundance of organisms or other factors.
Monoecious: Having both, male and female flowers, on the same plant.
Mosaic: A symptom of a plant viral disease that displays regular, light green, or yellow patches of tissue on leaves.
Mulch: A layer of material placed on the soil surface to prevent weed growth and reduce moisture loss.
Natural enemy: An organism known to control a pest species, including a predator, parasitoid, or pathogen.
Necrosis: Death of plant tissue accompanied by dark brown discoloration usually occurring in a well-defined part of a plant.
Necrotic: Dead or discolored brown plant tissue.
Nutlet: A small nut.
Nymph: The immature stage of an insect that goes through simple metamorphosis.
Opposite leaf arrangement: Two leaves are paired at the same node, one on each side of the stem.
Organic: A production or management system that utilizes fertilizers and pesticides that are naturally derived; a compound that contains molecules of carbon.
Ovate leaf: Egg-shaped leaf that is broadest at the base.
Overwinter: A stage of reduced activity and metabolism for an insect during the dormant season.
Palmate: Pattern of leaf veins radiating from a common point at the base of the leaf to the tips of the leaf lobes or leaflets.
Panicle: A branched flower cluster or inflorescence where flower stalks attach individual flowers to the stem.
Pathogen: A microganism capable of causing disease. Examples: fungi, viruses, and bacteria.
Perennial: A plant that can live three or more years and flowers at least twice.
Persistent: Attached to the plant beyond the usual time of falling.
Pest: An organism that causes a problem to humans concerns. Examples: insects, mites, pathogens, nematodes, plants, vertebrates, microbes.
pH: Numerical designation of acidity and alkalinity.
Phenological: Related to the stages of the life cycle of a plant. Examples: bud break, leafing out, or flowering.
Phloem: A layer of living cells below the bark responsible for transporting nutrients and plant food compounds; the innermost layer of bark.
Pinnate: A compound leaf that has leaflets arranged on either side of a common stalk, sometimes in pairs opposite each other.
Predator: An animal that feeds on other living organisms.
Preventive insecticide: A pesticide applied to inhibit the infestation of insects on susceptible trees or woody ornamentals.
Pupa: The stage of an insect between the larva and the adult that is primarily inactive and does not feed.
Resistance: A change in the sensitivity of a pest population to a pesticide, which results in a failure of the pesticide to control the pest.
Samara: Dry, winged fruit that does not split at maturity.
Sapwood: The living outer portion of the wood between the cambium and heartwood.
Scorch: Burned appearance of leaf edges caused by either environmental factors or infection.
Sensescence: Aging or death of plant tissue.
Serrated: Leaf margin with continuous, forward-pointing teeth.
Sign: The pathogen or its structures or products that are visible on a host plant.
Simple leaf: An undivided leaf where the blade is not divided into leaflets.
Simple metamorphosis: An insect’s change in form during development that involves egg, nymph, and adult stages.
Skeletonizing: A pattern of insect damage that involves chewing mainly on one side of the leaf while also leaving the main vein intact.
Soil drench: An application of a chemical solution directly to soil at the base of the tree or woody ornamental.
Sooty mold: Black, powder-like fungi that grow on the honeydew secretions of sap-sucking insects.
Spike: A flower cluster or inflorescence that is not branched; each flower is attached directly to the main stem with no stalk.
Stippling: Small, white flecking injuries to leaf surfaces due to sap-feeding insects.
Stomata: Tiny pores in plant leaves and needles that facilitate gas exchange.
Sunscald: Trunk and limb tissue injury resulting from rapid temperature changes, most commonly occurring in the winter.
Symptom: Internal or external reaction of a plant as a result of disease or injury.
Systemic: A pesticide that is absorbed through the leaves and roots of the plant and moves within the plant.
Target pest: A pest species that a control action is intended to destroy.
Threshold: A set level of insect or disease infection that must be reached before treatment is required. Examples: economic or aesthetic thresholds.
Two-ranked: Leaves or needles arranged in two vertical lines on opposite sides of the stem.
Two-valved: Fruit splits down both sides when ripe.
Vector: An organism able to transport and transmit a pathogen to a host.
Whorled leaf arrangement: More than two leaves are found at the same node.
Wilt: The loss of water from leaves, causing collapse.
