Active Ingredient
The chemical in a pesticide that controls the target pest.
Adjuvant
A chemical added to a pesticide formulation or tank mix to improve mixing, application or activity of a herbicide. Spray adjuvant examples include fertilizers, surfactants, methylated seed oils and crop oil concentrates.
Aeration
Removal of soil cores from a turf with hollow tines or spoons. This can help to alleviate soil compaction.
Alternate
Leaves appear singly at each node as in greenbriar or prostrate knotweed.
Annual
A plant starting from seed and completing its life cycle in the same growing season.
Arsonate Herbicide
a class of herbicides that poses very little concern as far as toxicity to humans. Their mode of action is not well understood. The arsonates are also very water soluble. Arsonates include DSMA, MSMA (Bueno 6, MSMA Turf), and CMA.
Auricle
A claw-like appendage projecting from the collar of the leaf.
Basal
Arising from the base of the stem.
Biennial
A plant starting from seed and requiring two years to complete its life cycle.
Blade
The flat portion of the grass leaf above the sheath.
Blend, Seed
A combination of two or more cultivars of the same species, e.g., Rebel and Falcon tall fescue.
Blighting of Entire Leaves
Disease symptoms cover whole leaves and produce a distinct border between healthy and diseased turf.
Blisters
Raised areas of diseased leaf tissue that change color and then rupture to release powdery masses of fungal spores.
Broadcast
Uniform application to an entire area.
Broadleaf
Plants with flattened leaves; dicots, i.e., plants that possess two seedling leaves. Broadleaf plant characteristics are widely varied. Leaves are generally wide (wider than they are long), and have net-like veins. They can have either round or square stems, and growth can be upright, prostrate or vining. Broadleaf plants can have a taproot, a bulbous root, or fibrous roots. They generally have showy flowers. Three key indicators help categorize a plant almost definitively as a broadleaf, rather than a grass, rush, or sedge: a square stem, a non-linear leaf shape, or a non-fibrous root system.
Bud Leaf
First emerged leaf of a grass plant.
Bunch Type Growth Habit
Plant development in the absence of rhizome and stolon production; a non-spreading grass.
Bunchgrass
A non-spreading grass which lacks rhizomes and stolons.
Capsule
A dry type of fruit that contains seed.
Carrier
An inert material added to an active ingredient to prepare a formulation of a pesticide.
Certified Seed
A seed lot inspected to meet minimum standards and to ensure trueness to type for a given cultivar.
Circles
Localized areas of disease damage in turf that are perfectly circular and greater than 4 inches in diameter.
Collar
A narrow band marking the place where the blade and sheath of a grass leaf join: divided--collar divided by the midrib; continuous--collar not divided by the midrib
Compaction
Soils that are subject to heavy traffic are prone to compaction (compression). Compacted soils reduce drainage, increase runoff, and inhibit root growth. Aerifying (aeration) helps to alleviate compaction.
Contact Herbicide
Herbicide that injures only those portions of the plant with which it comes into contact.
Cool-Season
A cool-season turfgrass species has optimum growth at temperatures between 60 and 75°F. Cool-season grasses include creeping bentgrass, fine fescue, tall fescue, Kentucky bluegrass, annual ryegrass, and perennial ryegrass.
Coring
Removal of soil cores from a turf with hollow tines or spoons.
Corm
A short, thickened, upright underground stem.
Creeping Growth Habit
Plant development at or near the soil surface that results in lateral spreading by rhizomes and/or stolons.
Crop Seed
Any seed grown for profit, often including undesirable grassy weeds, e.g., orchardgrass.
Crown
That portion of the grass plant which includes the stem apex, unelongated internodes, and lower nodes from which secondary roots begin.
Culm
A stem of a grass plant.
Cultivar
A cultivated variety of a species, e.g., K-31, Rebel, etc.
Cultivation
In turf, the working of the soil without the destruction of the turf.
Decumbent
Lying flat with apex tip growing upward.
Dicot
A plant having two seed leaves or cotyledons. Generally refers to broadleaf plants.
Dieback from Leaf Tip
Disease symptoms cover whole leaves, as they do for blighting, but they do not produce a distinct border between healthy and diseased turf.
Dinitroaniline (DNA) Herbicide
A class of herbicides that includes some of the most important soil-applied herbicides in turf. These herbicides are formulated as liquids, wettable dispersable granules, and granules. Herbicides in this class are mostly used to control crabgrass and goosegrass seedlings, as well as some small-seeded broadleaves. DNA herbicides are root inhibitors, and their primary mode of action is inhibition of mitosis. Examples include prodiamine (Barricade), benefin (Balan), pendimethalin (Pendulum, Pre-M, Weedgrass Control), and oryzalin (Surflan).
Dinitroaniline Herbicide
A class of herbicides that includes some of the most important soil-applied herbicides in turf. These herbicides are formulated as liquids, wettable dispersable granules, and granules. Herbicides in this class are mostly used to control crabgrass and goosegrass seedlings, as well as some small-seeded broadleaves. DNA herbicides are root inhibitors, and their primary mode of action is inhibition of mitosis. Examples include prodiamine (Barricade), benefin (Balan), pendimethalin (Pendulum, Pre-M, Weedgrass Control), and oryzalin (Surflan).
disease stand symptoms
Stand symptoms are an easily visible indication of some problem affecting the turfgrass. These are most easily observed by standing and looking across the turf area. Stand symptoms may be the result of nutritional deficiencies, drought or other environmental stresses, improper cultural practices, chemical injury, or pests. Man-made and environmental turf damage are often confused with pest-induced injury. Determining the cause of the problem is critical to effective turf management. When used in reference to diseases, there are several different types of stand symptoms, which basically describe the pattern of the disease on the lawn or landscape: circles, spots, patches, rings, or irregular, non-patterned symptoms across the turf stand.
DNA Herbicide
A class of herbicides that includes some of the most important soil-applied herbicides in turf. These herbicides are formulated as liquids, wettable dispersable granules, and granules. Herbicides in this class are mostly used to control crabgrass and goosegrass seedlings, as well as some small-seeded broadleaves. DNA herbicides are root inhibitors, and their primary mode of action is inhibition of mitosis. Examples include prodiamine (Barricade), benefin (Balan), pendimethalin (Pendulum, Pre-M, Weedgrass Control), and oryzalin (Surflan).
Dormancy
Resting stage through which the plant or ripe seeds usually pass and during which nearly all manifestations of life come to an almost complete standstill.
Emulsion
One liquid suspended in another, e.g., oil in water.
Eradication
Total removal of a pest.
Erosion
Whenever water, as intensive rainfall or irrigation, falls on bare soil surfaces in gardens or lawns, sand, silt, clay, and organic matter may be moved away from the site. The potential for erosion increases with slope, but unless there is runoff, raindrops cannot do much damage. It is the transportation of soil particles and organic matter in runoff that causes concern. This transported sediment can choke lakes and carry chemicals into waterways, making them unsuitable for recreational fishing, boating, or swimming. Everyone, including the urban resident, farmer, gardener, recreational enthusiast, and taxpayer must pay for the damage.
Flowable
A suspension consisting of finely ground, insoluble active ingredients in solid form mixed with a liquid and inert ingredients.
Four-Way
A combination product which is a mixture of either two, three, or four broadleaf herbicides that should be used when several different weed species present in the area being treated. Examples include Chaser 2 Amine (2,4-D amine + triclopyr), Trimec Classic (2,4-D amine, + mecoprop + dicamba), Escalade (2,4-D amine + fluroxypyr + dicamba), and Speed Zone (2,4-D ester + mecoprop + dicamba + carfentrazone).
Fruiting Bodies
Structures of various shapes and sizes that release fungal spores. Usually dark in color and embedded in the diseased plant tissue. May be found on all above- and below-ground parts of the turf plant.
Fumigant
A volatile material that vaporizes and destroys pests, e.g., methyl bromide.
Fungal signs
The visible evidence of the presence of a pathogen. Most turfgrass diseases are caused by fungi, and even though fungi are microscopic organisms, some produce larger structures at certain times in their life cycle that can be seen with the naked eye. Fungal signs include blisters on leaves, fruiting bodies, mycelium, mushrooms, puffballs, pustules on leaves, sclerotia, and spore masses.
Fungi
A major group of microorganisms commonly known as molds, mushrooms, and mildews; some cause disease.
Fungicide
A pesticide used to kill fungi.
Grass
Grasses are typically upright, bunching plants with fibrous roots. Some possess rhizomes or stolons. Their hollow stems are either round or flattened. Leaves have parallel veins, are in groups of two, and are much longer than they are wide. Generally, grasses have inconspicuous flowers. Leaf sheaths are usually split with overlapping edges; the collar is usually distinct.
Herbaceous
Refers to plants with non-woody stems that normally die back to the ground in the winter.
Herbicide
A pesticide used to kill weeds.
Herbicide, Arsonate
This class of herbicides poses very little concern as far as toxicity to humans. Their mode of action is not well understood. The arsonates are also very water soluble. Arsonates include DSMA, MSMA (Bueno 6, MSMA Turf), and CMA.
Herbicide, Contact
Herbicide that injures only those portions of the plant with which it comes into contact.
Herbicide, Dinitroaniline (DNA)
A class of herbicides that includes some of the most important soil-applied herbicides in turf. These herbicides are formulated as liquids, wettable dispersable granules, and granules. Herbicides in this class are mostly used to control crabgrass and goosegrass seedlings, as well as some small-seeded broadleaves. DNA herbicides are root inhibitors, and their primary mode of action is inhibition of mitosis. Examples include prodiamine (Barricade), benefin (Balan), pendimethalin (Pendulum, Pre-M, Weedgrass Control), and oryzalin (Surflan).
Herbicide, Non-selective
Herbicide that kills or injures all plants. Some plant species may exhibit more tolerance than others. Examples include glyphosate (Roundup, Touchdown Pro), and glufosinate (Finale).
Herbicide, Plant Growth Regulator (PGR)
This class of herbicides is used on more land area worldwide than any other herbicide group. The mode of action is not well understood, but in general they interfere with plant metabolism and transport. In turf, they are 2,4-D, 2,4-DB, clopyralid (Lontrel), triclopyr (Turflon Ester), and dicamba (Banvel).
Herbicide, Postemergence (POST)
Herbicide that needs to be applied after weeds emerge in order to be effective.
Herbicide, Preemergence (PRE)
Herbicide that needs to be applied prior to weed emergence in order to be effective. Can be applied before or after turf establishment. Rainfall or irrigation is often needed to move the chemical into the top few inches of the soil for best activity.
Herbicide, Selective
Herbicide that kills/injures some plants without harming others.
Herbicide, Sulfonylurea (SU)
A class of herbicides with high levels of activity at low application rates. In general, the SU herbicides are used to control annual bluegrass and perennial ryegrass during bermudagrass spring transition, as well as certain broadleaf weeds. Some members of this herbicide family also provide control of nutsedge and kyllinga species, and also dallisgrass when used with MSMA. The mode of action for this class is inhibition of the ALS enzyme that is used in biosynthesis. These chemicals are rapidly translocated, and resistance can become an issue. Examples include sulfosulfuron (Certainty), metsulfuron (Manor), trifloxysulfuron (Monument), foramsulfuron (Revolver), and rimsulfuron (TranXit GTA).
Herbicide, Systemic
Herbicide that is taken up through contact with the leaves or through the soil (via contact with the roots) and is moved throughout the plant to kill the whole plant.
Herbicide, Triazine
A class of herbicides which has inhibition of photosynthesis as the main mode of action. They are readily absorbed by both the roots and foliage of plants. This class of herbicides has tight restrictions due to concerns about atrazine leaching into groundwater. Triazines include atrazine (Purge, AAtrex), simazine (Princep, Regal Wynstar), and metribuzin (Sencor 75 Turf).
Herbicide, Two-, Three-, or Four-Way Broadleaf
A combination product which is a mixture of either two, three, or four broadleaf herbicides that should be used when several different weed species present in the area being treated. Examples include Chaser 2 Amine (2,4-D amine + triclopyr), Trimec Classic (2,4-D amine, + mecoprop + dicamba), Escalade (2,4-D amine + fluroxypyr + dicamba), and Speed Zone (2,4-D ester + mecoprop + dicamba + carfentrazone).
Hybrid
The progeny resulting from a cross of individuals differing in one or more heritable characters.
Inflorescence
The flowering portion of a plant.
Insect
Members of the animal kingdom; all mature insects have six legs and three body segments.
Insecticide
A pesticide used to kill insects.
Irregular symptoms
Non-patterned areas of diseased turf across the turf stand (i.e., not circles, patches, spots, or rings).
Larva
A stage in the development of certain insects; caterpillars (butterfly larva) or grubs (beetle larva).
LD50
A lethal dose for 50 percent of the test animals.
Leaf Spot
Round or oval area on the leaf with a distinct border, which is usually a different color than the center of the spot.
leaf venation
An arrangement of the youngest leaf in the bud shoot; rolled or folded.
Lesion
A localized area of diseased tissue which is irregular in shape with a distinct border that is usually a different color. Lesions may appear on either leaves or leaf sheaths. Leaf lesions are typically larger than a leaf spot.
Ligule
A thin projection from the top of the leaf sheath in grasses; it may be a fringe of hairs, membranous, or absent.
Lobe
Any rounded portion of a leaf.
Mixture, Seed
A combination of two or more species; e.g., Kentucky bluegrass and perennial ryegrass.
Mode of Action
The way that a pesticide works to kill an organism.
Monocot
A plant having one seed leaf or cotyledon. Grasses are monocots, as are orchids, lilies, daffodils, and tulips.
Mushrooms
Spore-producing structures with a cap and stem produced on the turf surface by Basidiomycete fungi.
Mycelium
A cottony or cobweb-like mass of fungal growth that certain fungi produce when the turf is wet or humidity is high.
Nematicide
A pesticide used to kill nematodes.
Nematode
A microscopic, worm-like organism that feeds on the roots of all plants, including turfgrasses. Nematodes cause roots to be stunted and clubbed, rot, dieback, and have little branching. Above ground, nematode feeding causes slow growth, turf thinning, poor response to fertilization and irrigation, wilting during dry weather, and weed invasion.
Nitrogen
Nitrogen is the most important element in turfgrass culture. It is required for the formation of chlorophyll which is then used for photosynthesis. Nitrogen is also found in numerous plant proteins, amino acids, enzymes, and vitamins. Nitrogen is primarily absorded through the roots in the nitrate (NO3-) form, but can also be taken up in the ammonia form (NH4+). Nitrogen rich fertilizers are often used to enhance and maintain turf appearance (green color) and density. Nitrogen sources are normally referred to as quick release or slow release. Quick release sources (e.g., ammonium nitrate) are water-soluable and produce fast turf greening. These sources have a short residual and a high burn potential. Slow release sources of nitrogen (e.g., IBDU, Urea formaldehyde) are typically organic materials broken down over time by soil microorganisms. These materials produce slow slow turf green-up, have a long residual, and low burn potential.
Node
A joint where leaves, roots, branches, or stems arise.
Non-selective Herbicide
Herbicide that kills or injures all plants. Some plant species may exhibit more tolerance than others. Examples include glyphosate (Roundup, Touchdown Pro), and glufosinate (Finale).
Nutrient Management
An attractive lawn, vigorously growing shrubs and flowers that show off the house, and a productive garden are the pride and joy of many homeowners. Fertilizer nutrients, especially nitrogen, phosphorus, and potassium, contribute to the health and beauty of these plants. Nitrogen and phosphorus, however, must be managed carefully to ensure that excessive amounts do not degrade water quality. Too much nitrogen and phosphorus along with carbon in surface water cause eutrophication (death from excessive algae growth) in rivers, lakes, and ponds. High nitrogen levels in groundwater and surface water can lead to the ingestion of nitrogen in its nitrate (NO3) form, which can cause health problems in humans and livestock. Phosphorus accumulates in lakes and ponds primarily from inflow of sediment that has phosphorus attached to it. Preventing erosion greatly reduces the likelihood of phosphorus being a threat to water quality. Nitrogen, whether from compost or fertilizer, may leach past plant roots and accumulate in groundwater or eventually move out to surface impoundments if not used completely by grass, shrubs, or garden crops.
Nymph
A stage in the development of certain insects where the young resemble the adult in form, eat the same food, and reside in the same environment.
Opposite
Leaves appear in pairs at each node along the stem.
Palmate
Palmate is used to describe both compound leaves and leaf venation. A <i>palmate leaf</i> is a compound leaf with four or more leaflets attached to the petiole at one location. Leaves with <i>palmate venation</i> have the main veins arising from the base of the leaf where it joins the petiole. A leaf with palmate venation may be either lobed or unlobed.
Panicle
Seedhead in which the side branches are attached to the main axis with a stalk. May form a triangular shape.
Parallel
Leaf veins begin at the base of the leaf and run lengthwise along the whole leaf.
Parts Per Million (PPM)
The number of parts by weight or volume of a constituent in 1,000,000 parts of the final mixture, by weight or volume.
Patches
Localized areas of diseased turf that are irregularly shaped and greater than 4 inches in diameter.
Pathogen
The causal agent of disease.
Perennial Plant
A plant that may or may not start from seed, may or may not produce seed, and lives more than two years.
Pest
An organism which is destructive or harmful to the crop (in this case, turfgrass). Major types of pests include diseases (fungi), insects, nematodes, and weeds. Moles, voles, millipedes, mites, earthworms, and even crayfish can sometimes be considered pests of turfgrass.
Pesticide
A chemical which kills pests. Pesticides include fungicides, herbicides, insecticides, and nematicides.
PGR
Plant growth regulators (PGRs) are chemicals which control some aspect of plant growth or development. In turf, these chemicals are used to suppress foliar growth or seedhead development. PGRs include ethephon (Ethephon and Proxy), flurprimidol (Cutless), maleic hydrazide (Retard, Royal Slo-Glo, and Liquid Growth Retardant), mefluidide (Embark), metsulfuron methyl (Escort), paclobutrazol (TGR Turf Enhancer and Trimmit), and trinexapac-ethyl (Governor and Primo Maxx).
Phytotoxic
Poisonous to plants.
Pinnate
Pinnate is used to describe both compound leaves and leaf venation. A <i>pinnate leaf</i> is a compound leaf which has leaflets arranged along the sides of a common axis; feather-like. There is sometimes a terminal leaflet at the end of the central axis. A leaf or leaflet with <i>pinnate venation</i> has veins arranged in pairs on either side of a central midrib vein. A leaf with pinnate venation may be either lobed or unlobed. The trifoliate leaf shown in the middle photograph below is a pinnate leaf with pinnate venation.
Plant Growth Regulator
Plant growth regulators (PGRs) are chemicals which control some aspect of plant growth or development. In turf, these chemicals are used to suppress foliar growth or seedhead development. PGRs include ethephon (Ethephon and Proxy), flurprimidol (Cutless), maleic hydrazide (Retard, Royal Slo-Glo, and Liquid Growth Retardant), mefluidide (Embark), metsulfuron methyl (Escort), paclobutrazol (TGR Turf Enhancer and Trimmit), and trinexapac-ethyl (Governor and Primo Maxx).
Plant Growth Regulator (PGR) Herbicide
This class of herbicides is used on more land area worldwide than any other herbicide group. The mode of action is not well understood, but in general they interfere with plant metabolism and transport. In turf, they are 2,4-D, 2,4-DB, clopyralid (Lontrel), triclopyr (Turflon Ester), and dicamba (Banvel).
Postemergence (POST) Herbicide
Herbicide that needs to be applied after weeds emerge in order to be effective.
Postemergence Herbicide
Herbicide that needs to be applied after weeds emerge in order to be effective.
Power Raking
Removal of debris with rapidly rotating vertical tines or brush.
Preemergence (PRE) Herbicide
Herbicide that needs to be applied prior to weed emergence in order to be effective. Can be applied before or after turf establishment. Rainfall or irrigation is often needed to move the chemical into the top few inches of the soil for best activity.
Preemergence Herbicide
Herbicide that needs to be applied prior to weed emergence in order to be effective. Can be applied before or after turf establishment. Rainfall or irrigation is often needed to move the chemical into the top few inches of the soil for best activity.
Prophyll
The first leaf of a branch off the main axis; a sheath-like structure.
Prostrate
Low growing; hugging the ground.
PSI
Pounds per square inch.
Puffballs
A spherical spore-producing structure up to 3" in diameter produced on the turf surface. This fungal symptom is similar to a mushroom, but lacking a stem or stalk.
Puffiness
A spongy, irregular surface.
Pustules
Small, spherical structures containing fungal spores which are produced on diseased leaf surfaces.
Quick Release Nitrogen
Nitrogen is the most important element in turfgrass culture. It is required for the formation of chlorophyll which is then used for photosynthesis. Nitrogen is also found in numerous plant proteins, amino acids, enzymes, and vitamins. Nitrogen is primarily absorded through the roots in the nitrate (NO3-) form, but can also be taken up in the ammonia form (NH4+). Nitrogen rich fertilizers are often used to enhance and maintain turf appearance (green color) and density. Nitrogen sources are normally referred to as quick release or slow release. Quick release sources (e.g., ammonium nitrate) are water-soluable and produce fast turf greening. These sources have a short residual and a high burn potential. Slow release sources of nitrogen (e.g., IBDU, Urea formaldehyde) are typically organic materials broken down over time by soil microorganisms. These materials produce slow slow turf green-up, have a long residual, and low burn potential.
Raceme
Seedhead in which more than one slender spike is attached along the end of the stem. Individual spikes can be attached at one point or along the top of the stem in an alternate fashion.
Raking, Power
Removal of debris with rapidly rotating vertical tines or brush.
Resistance
Resistance is the inherited ability of an organism (turfgrass, weed, disease, insect, etc.) to survive exposure to a dose of pesticide (herbicide, fungicide, insecticide, etc.) normally lethal to the wild type of the organism. Continual use of pesticides with similar control mechanisms (modes of action) can result in pests that are resistant to some chemicals. Poor or ineffective pest control can be expected when this occurs. Managers can reduce the chances of this happening by mixing or alternating pesticides belonging to different chemical classes.
Rhizome
An underground creeping stem which can produce roots and shoots at each node.
Rings
Circular areas of diseased turf with healthy turf to the inside and outside, leaving a ring-like pattern on the turf stand.
Rosette
A cluster of leaves radiating out from a central axis.
Rush
Rushes are upright plants of the Juncaceae family. Like grasses and sedges, they have fibrous roots. Rushes have round, solid stems. Like sedges, their leaves are borne in groups of three. Leaves are either alternate or basal, parallel veined, and are much longer than they are wide. Rushes are considered semi-aquatic, and like sedges, will be found where there is an abundance of water. Rush flowers are solitary and arranged in heads, making them distinctly different from both grasses and sedges.
Scalping
Excessive removal of turf leaves by close mowing. Results in a brown, stubbly appearance.
Sclerotia
Seed-like, compact masses of fungal tissue that allow fungi to survive unfavorable conditions. Small round or threadlike structures which are produced on the diseased turf or in the thatch layer by certain fungi.
Sedge
Sedges are members of the Cyperaceae family. They are upright plants with fibrous roots and stolons. Sedges can be distinguished from grasses and rushes by stem shape. Sedges generally have solid triangular stems, whereas rushes have solid round stems and grasses have hollow round or flattened stems. Sedges have leaves in groups of three, while grasses have leaves in groups of two. Sedge leaf edges are usually rough; leaf sheaths are tubular, not split; the collar is usually indistinct; auricles are absent; and ligules are small or absent. Like rushes, sedges are considered semi-aquatic, and will be found where there is an abundance of water but are also found in drier areas. Sedge flowers are usually one to many spikelets.
Seed Blend
A combination of two or more cultivars of the same species, e.g., Rebel and Falcon tall fescue.
Seed Mixture
A combination of two or more species; e.g., Kentucky bluegrass and perennial ryegrass.
Seed, Certified
A seed lot inspected to meet minimum standards and to ensure trueness to type for a given cultivar.
Selective Herbicide
Herbicide that kills/injures some plants without harming others.
Semiarid Turfgrass
Turfgrasses adapted to grow in semiarid regions without irrigation, such as buffalograss, gramagrass, and wheatgrasses.
Sepals
The floral organs found at the base of the flower; usually green and somewhat leaflike.
Sessile
Directly attached without a stem or stalk.
Sheath
The basal portion of the leaf surrounding the grass stem. In grass plants, it is usually split with overlapping edges, but may also be open or closed.
Site of Action
The way that a pesticide works to kill an organism.
Slicing
Penetration of turf in a vertical plane by series of solid flat tines.
Slow Release Nitrogen
Nitrogen is the most important element in turfgrass culture. It is required for the formation of chlorophyll which is then used for photosynthesis. Nitrogen is also found in numerous plant proteins, amino acids, enzymes, and vitamins. Nitrogen is primarily absorded through the roots in the nitrate (NO3-) form, but can also be taken up in the ammonia form (NH4+). Nitrogen rich fertilizers are often used to enhance and maintain turf appearance (green color) and density. Nitrogen sources are normally referred to as quick release or slow release. Quick release sources (e.g., ammonium nitrate) are water-soluable and produce fast turf greening. These sources have a short residual and a high burn potential. Slow release sources of nitrogen (e.g., IBDU, Urea formaldehyde) are typically organic materials broken down over time by soil microorganisms. These materials produce slow slow turf green-up, have a long residual, and low burn potential.
Soil
A substrate of material made up of rocks and minerals, organic matter, and water. Soil makes up the top layer of the surface of the earth. Properties of soil include texture, color, structure and bulk density. Soil is a constantly evolving structure, based upon weather, plant material, water and other inputs.
Soil Compaction
Soils that are subject to heavy traffic are prone to compaction (compression). Compacted soils reduce drainage, increase runoff, and inhibit root growth. Aerifying (aeration) helps to alleviate compaction.
Soil Erosion
Whenever water, as intensive rainfall or irrigation, falls on bare soil surfaces in gardens or lawns, sand, silt, clay, and organic matter may be moved away from the site. The potential for erosion increases with slope, but unless there is runoff, raindrops cannot do much damage. It is the transportation of soil particles and organic matter in runoff that causes concern. This transported sediment can choke lakes and carry chemicals into waterways, making them unsuitable for recreational fishing, boating, or swimming. Everyone, including the urban resident, farmer, gardener, recreational enthusiast, and taxpayer must pay for the damage.
Soil Fumigant
A volatile material that vaporizes and destroys pests, e.g., methyl bromide.
Soil Sterilant
Any chemical applied to the soil that prevents growth of plants for a long time.
Solution
Physically uniform mixture of two or more liquids.
Spike
Seedhead in which the side branches are attached to the main axis without a stalk.
Spiking
Penetration of turf in a vertical plane by series of solid round tines.
Spore
A microscopic seed-like reproductive unit that can germinate and give rise to more fungi. Spore masses appear as fuzzy or jelly-like growths on the diseased tissue, and usually appear when the turf is wet or humidity is high.
Spots
Localized areas of diseased turf less than 4 inches in diameter.
Spreader
An ingredient that helps pesticides come in closer contact to the plant surface.
Sprig
A stolon or rhizome used to establish a turf.
Stamen
The male part of a flower that produces the pollen.
Stand symptoms
Stand symptoms are an easily visible indication of some problem affecting the turfgrass. These are most easily observed by standing and looking across the turf area. Stand symptoms may be the result of nutritional deficiencies, drought or other environmental stresses, improper cultural practices, chemical injury, or pests. Man-made and environmental turf damage are often confused with pest-induced injury. Determining the cause of the problem is critical to effective turf management. When used in reference to diseases, there are several different types of stand symptoms, which basically describe the pattern of the disease on the lawn or landscape: circles, spots, patches, rings, or irregular, non-patterned symptoms across the turf stand.
Sterilant
Any chemical applied to the soil that prevents growth of plants for a long time.
Sticker
An ingredient that helps pesticides stick to plants.
Stipule
Appendage at the base of a leaf.
Stolon
An above-ground creeping stem that can produce roots and shoots at each node.
Sulfonylurea (SU) Herbicide
A class of herbicides with high levels of activity at low application rates. In general, the SU herbicides are used to control annual bluegrass and perennial ryegrass during bermudagrass spring transition, as well as certain broadleaf weeds. Some members of this herbicide family also provide control of nutsedge and kyllinga species, and also dallisgrass when used with MSMA. The mode of action for this class is inhibition of the ALS enzyme that is used in biosynthesis. These chemicals are rapidly translocated, and resistance can become an issue. Examples include sulfosulfuron (Certainty), metsulfuron (Manor), trifloxysulfuron (Monument), foramsulfuron (Revolver), and rimsulfuron (TranXit GTA).
Sulfonylurea Herbicide
A class of herbicides with high levels of activity at low application rates. In general, the SU herbicides are used to control annual bluegrass and perennial ryegrass during bermudagrass spring transition, as well as certain broadleaf weeds. Some members of this herbicide family also provide control of nutsedge and kyllinga species, and also dallisgrass when used with MSMA. The mode of action for this class is inhibition of the ALS enzyme that is used in biosynthesis. These chemicals are rapidly translocated, and resistance can become an issue. Examples include sulfosulfuron (Certainty), metsulfuron (Manor), trifloxysulfuron (Monument), foramsulfuron (Revolver), and rimsulfuron (TranXit GTA).
Surfactant
Several classes of chemicals that reduce the interfacial tension between water and plant material or other liquids. Classes of surfactants include wetting agents, spreaders, and stickers. Types of surfactants include anionic, cationic, and nonionic. The most common type of surfactant used in herbicide applications is nonionic.
Symptom
The visual characteristics associated with a given disease.
Systemic Herbicide
Herbicide that is taken up through contact with the leaves or through the soil (via contact with the roots) and is moved throughout the plant to kill the whole plant.
Thatch
A tightly intermingled layer of undecomposed roots, stems, and shoots located between the soil surface and the green vegetation of the turf grass.
Three-Way
A combination product which is a mixture of either two, three, or four broadleaf herbicides that should be used when several different weed species present in the area being treated. Examples include Chaser 2 Amine (2,4-D amine + triclopyr), Trimec Classic (2,4-D amine, + mecoprop + dicamba), Escalade (2,4-D amine + fluroxypyr + dicamba), and Speed Zone (2,4-D ester + mecoprop + dicamba + carfentrazone).
Throat
The region between the sheath and blade on the ligule side of the leaf.
Tiller
A grass plant shoot arising in the axes of leaves in the unelongated portion of the stem.
Tolerance
The inherent ability of a species (turfgrass, weed, disease, insect, etc.) to withstand application of a pesticide (herbicide, fungicide, insecticide, etc.) at the normal dosage without being killed or injured. Specific tolerance may be associated with an anatomical or physiological characteristic in the plant or other organism.
Topdressing
A sand or prepared soil mix applied to the turf to help smooth the surface, enhance establishment, and reduce thatch buildup.
Toxicity
A term used to define a products hazard potential.
Triazine Herbicide
A class of herbicides which has inhibition of photosynthesis as the main mode of action. They are readily absorbed by both the roots and foliage of plants. This class of herbicides has tight restrictions due to concerns about atrazine leaching into groundwater. Triazines include atrazine (Purge, AAtrex), simazine (Princep, Regal Wynstar), and metribuzin (Sencor 75 Turf).
Trifoliate
Leaf consisting of three leaflets, e.g., clover.
Tuber
An underground stem modified for food storage that is attached to the root system as found in yellow nutsedge.
Turf
A covering of mowed vegetation, usually a grass.
Turf Tolerance
The inherent ability of a species (turfgrass, weed, disease, insect, etc.) to withstand application of a pesticide (herbicide, fungicide, insecticide, etc.) at the normal dosage without being killed or injured. Specific tolerance may be associated with an anatomical or physiological characteristic in the plant or other organism.
Turfgrass
A species or cultivar of grass, usually of spreading habit, which is maintained as a mowed turf. North Carolina sits in the transition zone for cool- and warm-season turfgrasses: both types are grown here. Identifying the turfgrass species is critical to effective turfgrass management. Proper management depends on knowledge of the species growth habits, tolerances of cultural methods, and susceptibilities to damage from environmental stresses, including pests.
Two-, Three-, or Four-Way
A combination product which is a mixture of either two, three, or four broadleaf herbicides that should be used when several different weed species present in the area being treated. Examples include Chaser 2 Amine (2,4-D amine + triclopyr), Trimec Classic (2,4-D amine, + mecoprop + dicamba), Escalade (2,4-D amine + fluroxypyr + dicamba), and Speed Zone (2,4-D ester + mecoprop + dicamba + carfentrazone).
Two-Way
A combination product which is a mixture of either two, three, or four broadleaf herbicides that should be used when several different weed species present in the area being treated. Examples include Chaser 2 Amine (2,4-D amine + triclopyr), Trimec Classic (2,4-D amine, + mecoprop + dicamba), Escalade (2,4-D amine + fluroxypyr + dicamba), and Speed Zone (2,4-D ester + mecoprop + dicamba + carfentrazone).
Venation
Appearance of veins in the leaves. Leaf venation can be defined as pinnate, palmate, or parallel.
Vernation
An arrangement of the youngest leaf in the bud shoot; rolled or folded.
Volatile
Likely to vaporize.
Warm-Season
A warm-season turfgrass has its optimum growth at temperatures between 80 and 95F. Warm-season grasses include bahiagrass, bermudagrass, carpetgrass, centipedegrass, St. Augustinegrass, and zoysiagrass.
Weed
A plant growing where it is not wanted.
Wetting Agent
A chemical that aids in liquid-to-surface contact.
Whorl
Three or more flowers, branches, or leaves located at one node.