Absorption: The entry of a chemical or nutrient into the plant.

Acid Soil: A soil whose pH is less than 7.

Aeration (Soil): The exchange of air between the soil and the atmosphere.

Alkaline Soil: Soil whose pH is more than 7.

Annual Plant: A plant completing its normal growth cycle in one year or less.

Annual, Winter: A plant that begins growth in the fall; survives over winter, flowers and produces seed and dies the following season.

Biennial: A plant whose normal growth cycle spans two growing seasons. Many biennials produce roots and a cluster of leaves near the surface of the ground the first year; flower, produce seed and die the second year.

Blade (Leaf): The flattened portion of the leaf projecting outward from the main shoot axis and located above the sheath.

Blend (Seed): A combination of two or more varieties (cultivars) of a single turfgrass species.

Broadcast Application: Uniform distribution of a pesticide or fertilizer over an entire area.

Broadleaf: A term applied to non grass-like plants; typically used in context of weed control. Examples include dandelion and white clover.

Broadleaf Herbicide: A weed killer designed specifically to kill broadleaf plants.

Bermuda: Species of coarse grass used in hot climates.

Burn: Chemical burns caused by over fertilizing.

Calibrating: The process of checking a mechanical applicator (a fertilizer spreader or a sprinkler) to insure that it will accurately deliver the right amount of material to the right amount of area.

Clippings: Leaf blades or stems cut off by mowing.

Compaction (of Soil): Increase in soil density through destruction of its pore space, as by excessive traffic or working the soil especially when it’s wet.

Complete Fertilizer: Any fertilizer product containing at least nitrogen, phosphorus, and potassium.

Compost: It is made by piling a mixture of grass clippings, leaves, etc., in a mound and, periodically stirring and mixing the pile to fasten up the decomposition process.

Contact Herbicide: A weed killer that kills by contact with plant tissues.

Crown: A tightly compressed stem-like structure that pushes new leaves upward as they form and grow. In lawn grasses it is located at the base of the plant at or near the soil line. The location of the crown allows regular mowing to be done while not compromising the plant’s ability to re-grow.

Cultivar: A group of cultivated plants distinguished by various features such as growth habit or leaf form that, when reproduced through seed or vegetative means, retain their distinguishing features.

Cultivation: As applied to turf, cultivation means working the soil and/or thatch without destroying the entire lawn surface. Examples include coring or slicing.

Cultural Practices: Various horticultural methods and techniques used for plants in the yard and garden such as watering, fertilizing, mowing, weeding, and edging.

Damage Threshold Level: The lowest amount of a pest population where unacceptable levels of damage occur.

Decomposition: The rotting or decaying of an organic substance.

Deficiency (of Nutrients): Growth symptoms (such as chlorosis) caused by insufficient supply or unavailability of plant nutrients.

Dichlorophenoxyacetic Acid (2, 4-D): A weed killer often used for controlling broadleaf weeds in lawn areas.

Disease: An interaction between a grass plant, pathogen and its environment that results in abnormal growth and/or appearance.

Dormant (Plant): A condition of significantly reduced activity with very less or no growth. All physiological activities, like photosynthesis, are minimal or non-existent.

Drought tolerance: The grass plant’s ability to withstand extended periods of dry conditions, incurring permanent damage.

Ecosystem: The interaction of a turfgrass community with other plants, animals and their surrounding environment.

Endophyte: A plant living and functioning within another plant. For example, a fungus.

Erosion: The wearing away of soil from land areas by wind or running water.

Evapotranspiration: Sum of all the moisture lost through evaporation and transpiration.

Fertilizer: Nutrient supplements that fuel healthy plant growth. The most common nutrients contained in fertilizers are nitrogen, phosphorus, and potassium.

Fibrous Roots: Profusely branched roots consisting of many lateral rootlets and usually no main or taproot development.

Fertilizer Burn: Plant injury (and/or death) caused by desiccation of tissue due to contact with high concentration of certain fertilizers.

Fungi: Organisms which live off dead or living plants or animals.

Fungicide: A pesticide used to destroy or suppress fungi.

Fungus (pl. Fungi): A non-vascular plant that lacks chlorophyll. Some examples are: mushrooms, molds, rusts, and yeasts.

Germination: Sprouting of the root and shoot from a seed when environmental conditions are favorable.

Herbaceous: Plants with non woody stems normally dying back to the ground in the fall.

Herbicide: A specific category of pesticides used for controlling weeds.

High-maintenance Lawn: Lawn areas composed of turfgrass species requiring higher levels of water, fertilizing and mowing to remain healthy.

Host Plant: Any plant that provides nutrition (and habitat) for a plant pest to survive.

Inert: Not active

Infection: Establishment of a pathogen within a host plant.

Infiltration (Water): The physical process of water movement into the soil.

Insecticide: A category of pesticides used for controlling insects.

Lawn: That portion of a yard or land area covered with grass plants kept short through mowing.

Liquid Fertilization: A method of applying plant nutrients as a solution of dissolved fertilizer salts.

Mowing: The periodic cutting of a lawn area to a specified height.

Mulch: A non-living material used to cover the soil surface to control weeds, conserve moisture, reduce soil temperatures, and improve appearance. Examples are woodchips, compost, and leaves.

Mulching Mower: Mowers designed to finely chop grass clippings and forcibly direct them back into the lawn for a clean appearance.

Net Weight (Fertilizers): The actual weight of only the fertilizer nutrients contained in a packet of fertilizer.

Nitrogen: An essential nutrient required for plant growth. It is a significant component of plant proteins.

Noxious: A plant that is declared by a state authority to be so objectionable that efforts will be directed at its eradication.

N-P-K: Chemical symbols for nitrogen (N), phosphorus (P) and potassium (K). On a container of fertilizer, these nutrients are always expressed as percentages contained in the package and are always shown in the order N-P-K.

Nutrients (Plant): Mineral elements considered essential for plant growth. There are 16 minerals that are essential for plant nutrition.

Nutrient Release Rate: The speed at which plant nutrients, especially N, become available for plant use following application to a lawn.

Organic: Chemical compounds containing the element carbon other than the inorganic carbonates. Often refers to any part of, or anything produced by, plants or animals.

Overseed or Overseeding: The process of incorporating seed into an existing lawn area for the purpose of lawn repair or introduction of different grass species.

Patch Disease: A non-specific term applied to small dead, circular areas in a lawn caused by a number of different pathogens. Symptoms may include the appearance of dead rings of grass with green grass inside and outside of the ring.

Peat: A partly decomposed plant material found in marshy areas.

Perennial: Plants that live 2 or more years producing flowers and seeds in successive years.

Permeable: Allowing water or other substances to pass through such as a lawn.

Pest (Plant): Any insect, mite, rodent, fungus, weed, or other organism capable of causing stunted growth, injury or death through disease, consumption of the plant or competition.

Pesticide: Any chemical or biological agent used to control plant or animal pests in order to protect and/or preserve desirable plants.

Ph: A numerical measure of soil acidity or alkalinity based on the hydrogen ion (H+) concentration in the soil. A pH of 7 indicates neutral conditions (neither acidic nor alkaline); above 7 is basic (alkaline), below 7 is acidic.

Phosphorus: One of the major plant nutrients; important in root growth and plant energy functions. The middle alphabet of a fertilizer, N-P-K.

Post Emergence: The application of an herbicide after the weed has emerged (and is usually visible) from the soil.

Pre Emergence: The application of an herbicide before the weed emerges from the soil. Target plants are most often not visible above ground at the time of application.

Pure Live Seed (PLS): A seed lot’s percentage of seed that is pure and viable.

Purity: The degree of freedom (expressed as a percentage) from weed and other crop seeds.

Quick-Release Nitrogen Source: Nitrogen from these sources is available for use by the plant as soon as water is applied and the fertilizer granule dissolves. This can also be applied in liquid formulations. Plant responds with rapid rates of growth.

Recuperative Capacity: The ability of turfgrasses to recover from damage.

Reel Mower: A mower that cuts grass by means of a rotating reel of blades passing over a fixed blade (called a bed knife) attached to the frame.

Rhizome: An elongated underground stem with scale-like leaves and adventitious roots originating from the nodes.

Root: The fibrous, underground part of a plant associated with mineral and water absorption.

Rotary Mower: A mower that cuts turf by a high-speed, rotating metal blade positioned parallel to, and at a desired height above the turf surface.

Rotary Spreader: A spreader used in the application of fertilizer, that distributes the material in an arc, several feet wide, by means of a rotating disc below the fertilizer hopper.

Scalping: An undesirable mowing practice that removes an excessive amount of green leaves and shoots at any one mowing. It can seriously weaken or even kill the turfgrass.

Seed: A ripened ovule containing an embryo capable of producing a new plant.

Seed Count: The actual number of seeds of a particular species or variety contained in a seed blend or mixture.

Seed Weight: The actual weight of seeds from a particular species or variety contained in seed blend or mixture. Expressed as a percent of the total weight.

Seeding: The process of distributing seed over the soil surface, either mechanically or by hand, in an attempt to establish a new lawn or renovate an existing lawn.

Shade: An area of reduced light quantity (and often quality) resulting from the partial or complete obstruction of direct sunlight.

Sheath: The tube shaped, basal section of the grass leaf enclosing the stem.

Shoot Density: The number of shoots contained in a specified area of lawn.

Slit-Seeding: The process of seeding a new lawn area or over seed an existing area with the help of slit-seeders. Slit-seeders utilize a series of vertically rotating discs to cut small grooves into the soil while depositing seed into the grooves just behind the discs.

Sloughing-Off: The periodic shedding of plant parts.

Sod: Squares or strips (rolls) of turfgrass cut from a production field and usually with a thin layer of soil still attached. It is used for installing a new turfgrass area.

Sodding: Installing a turfgrass area utilizing sod.

Sod Cutter: A machine or hand tool that is designed to cut the grass plus a thin layer of soil from the ground. The length and thickness of the cut sod can vary.

Texture (Grass): The coarseness or fineness of a turfgrass.

Thatch: A dense, fibrous and partially decomposed layer of living and dead grass stems, leaves, and roots that accumulates between the green vegetation and soil surface.

Topsoil: The upper portion of soil that is generally higher in organic matter in comparison to the subsoil and usually has more favorable characteristics of soil fertility, aeration and structure.

Turf: A soil covering of mowed vegetation, usually a turfgrass.

Urea: A quick-release nitrogen fertilizer source. Usually available as 45-0-0 or 46-0-0. It is also known as a synthetic organic fertilizer as it contains the element carbon in its chemical structure.

Vigor (Plant): The genetic and environmental factors that determine the rate and amount that a turfgrass species or cultivar is able to grow and spread.

Vertical Mower: A high-speed machine with vertically rotating blades that slices into the turf to reduce thatch or improve soil aeration.

Warm-Season Turfgrass: Turfgrass species whose optimum growth occurs during the warmer periods (80º – 95º F) of the growing season.

Water Insoluble Nitrogen (WIN): That fraction of nitrogen contained in fertilizer not considered soluble in 25o C water.

Water Soluble Nitrogen (WSN): That fraction of nitrogen contained in fertilizer considered to be soluble in 25o C water. It is generally a measure of the quick-release nitrogen contained in the fertilizer.

Watering-In: Water applied to turf immediately after the application of some pesticides or fertilizers to dissolve and/or move materials into the soil.

Water logging: Soil saturated with water for an extended period of time, resulting in temporary anaerobic conditions.

Weed: An undesired, uncultivated plant growing in a manner so as to adversely compete with desirable plants for water, light and nutrients, or destroy aesthetic qualities of a lawn.

Glossary sourced from: http://www.sustland.umn.edu/index.html