Natural -
occurring in nature.
Nematodes -
microscopic, elongated, cylindrical, parasitic worms that live in water
and soil.
Node - the
location on a stem where buds form.
Nodules - swellings
on the roots of legumes where nitrogen-fixing bacteria live.
Nonselective pesticide
- a poison that kills a wide variety of pest species.
Nutrients -
substances a plant takes in and uses as food for growth and development.
Nymph -
a stage or series of size changes between egg and adult in the life cycle of
insects that go through incomplete or simple metamorphosis.
Organic - of plant or animal origin.
Ovary - the swollen
bottom part of the pistil that contains the ovules or immature seeds.
Oxygen, O2,
- a colorless, tasteless, odorless gas that is 1/5 of the volume of the
atmosphere.
Parasitic - an
organism that lives on or in another living organism (the host) and
obtains nutrition from the host.
Pathogen - a
disease-causing organism.
Pelletized - the
coating and forming into pellets of very small seed so they are easier
to handle.
Penetration - the
point at which a pathogen enters a host.
Perennial ryegrass -
a cool-season turfgrass with seeds that germinate quickly. The cultural
requirements are similar to those of Kentucky bluegrass; however, it is
not quite as hardy or disease resistant as bluegrasses.
Perennials - plants
that do not die after flowering, but live from year to year.
Petals - a whorl of
structures that surround the inner reproductive organs of a flower.
Together they are called the corolla. They often attract insects by
color or nectar, facilitating pollination.
Pheromone - a
chemical substance that convey information to and produce specific
responses in certain animals.
Phloem - the part of
the vascular system that moves food through the plant.
Photoperiodism -
responses of plants to the relative lengths of light and dark cycles.
Photosynthesis - the
production of sugar from carbon dioxide and water in the presence of
chlorophyll, activated by light energy and releasing oxygen.
Phototropism - the
bending of a plant toward the direction of more intense light.
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Pinch - breaking off
the terminal growing point of a plant to encourage axillary buds to
grow.
Pistil - the female
part of the flower, consisting of one or more carpels and enclosed
ovules.
Pollard - a tree cut
back to the trunk to make a dense cluster of branches and foliage.
Pollen - the
microspores that carry the male gametophyte of seed plants.
Pollination - the
transfer of pollen from the anther to the stigma.
Pollinator - an
insect or other vehicle by which pollen is carried from one flower to
another. A plant that provides pollen for a self-infertile plant.
Post-emergent herbicide
- a pesticide that kills plants after they have grown to seedling stage
or beyond.
Potpourri - a
mixture of dried flower petals with herbs and spices used for its
fragrance.
Potting medium -
material used for growing plants in containers. Mixes may include
vermiculite, perlite, sand, peat, charcoal, loam and fertilizer.
Pre-emergent herbicide
- a pesticide that kills plants as they germinate.
Primocanes - on
raspberries and blackberries, new, first-year canes.
Procumbent - having
stems that trail along the surface.
Propagation - to
increase the number of plants by sexual or asexual meansProtozoans
- organisms made up of a single cell or a group of basically identical
cells.
Prune - to cut back
parts of plants for better shape, disease control or improved fruiting.
Pupa - a stage in
complete metamorphosis when an insect transforms from the larval to
adult stage of development.
Raised bed - a
gardening area where the soil has been elevated above ground level. This
gardening technique is especially used where soil drainage is poor. Beds
can be raised in a structure of wood, brick, cement blocks, etc.
Rasping - mouthparts
that are rough and used to scrape a surface to feed.
Reel mower - a mower
with multiple blades mounted on a cylinder. The blades cut against a
bar. It makes precise cuts and is ideal for lower mowing heights. The
blades require professional sharpening. These mowers are safer to use
than rotary mowers.
Renewal spur - on
grapevines, the cane pruned to one or two nodes on the cordon; becomes
the fruiting cane the following year.
Renovation -
removing an old planting and putting in a new one or removing and
replacing only part of a planting. In strawberry culture, this process
involves removing the leaves of the plants and cultivating the aisle to
reduce the width of the row of plants to no more than 15 inches.
Respiration - the
process where food is oxidized (burned) to release energy.
Rhizome - an
underground, horizontal stem.
Root - the portion
of the plant usually found below ground. They are distinguished from
stems by not having nodes.
Root girdling -
encircling roots at or below the surface of the ground that tend to
strangle the plant.
Root hairs - tubular
outgrowths of surface cells of the root.
Root prune - to cut
back the roots of a plant to encourage them to develop more fibrous
roots or to reduce the mass of roots. Usually done before transplanting
established plants or repotting houseplants.
Rooting hormone - a
chemical that stimulates the growth of roots.
Rootstock - the root
onto which a scion or bud is grafted or budded.
Rotary mower - a
mower with a blade that spins in a horizontal plane from a central rod.
Its advantages are the ability to cut tall grass, versatility of
movement, a less expensive purchase price and blades that can be easily
sharpened.
Row cover fabric - a
loosely woven translucent fabric used to keep insect pests off crops. It
also functions as a cloche.
Saprophyte - an
organism that obtains nutrition from dead organic matter.
Scarification - the
physical or chemical treatment given to some seeds in order to weaken
the seed coat sufficiently for germination to occur.
Scion - the upper
part of the union of a graft.
Scorch - injury to
leaves due to lack of sufficient water, excessive transpiration or
injury to the water-conducting system of the plant.
Seed - the organ
that forms after fertilization occurs.
Selective herbicide
- a pesticide that kills only one type of plant, for example broadleaf
herbicides only kill broadleaf weeds, not turfgrasses.
Self-cleaning -
herbaceous plants that drop spent blossoms, thus not requiring
deadheading.
Sepals - structures
that usually form the outermost whorl of a flower. Together, they are
called the calyx.
Sewage sludge - the
solid matter that settles out during the treatment of sewage.
Sexual reproduction
- production of new generations involving the exchange of chromosomes
from both a male and female parent.
Sharp sand - a
coarse sand used in building.
Short-day plant - a
plant that requires a night longer than its critical dark period,
usually 12 hours or more, to develop flowers.
Side-dress - to
apply fertilizer to the side of a row of growing plants or around single
plants.
Slice seed - a
technique used to sow seed. A machine cuts or slices grooves into the
lawn or soil and drops seeds directly into the grooves. It is used to
fill in a thinning lawn without disturbing the existing grass
excessively.
Soaker hose - a
porous tube that allows water to seep from it; used to irrigate plants.
It is used to conserve water and to avoid wetting plant foliage.
Softwood cutting - a
nonwoody piece of a woody plant that is cut from the stock plant to
asexually propagate a new individual plant.
Soil -
The top layer of the earth's surface, consisting of rock and mineral particles
mixed with organic matter.
Soil conditioner -
any material added to soil to improve its structure, texture, tilth or
drainage.
Soilless mix -
potting medium that contain a mixture of ingredients from the materials
listed for potting medium, but no mineral soil.
Soluble salt - salts
from fertilizers and tap water that are dissolved in water.
Solvent - a liquid
that can dissolve a substance.
Species - a group of
closely related individuals that have the potential to reproduce with
each other; a unit of classification.
Specific epithet -
the second name of the binomial given to a species; for instance,
"rubrum" is the species epithet of Acer rubrum.
Spines - a
sharp-pointed woody structure, usually a modified leaf or leaf part.
Spore - a minute
reproductive body produced by primitive organisms, such as ferns and
fungi.
Sporophyte - the
part of a life cycle when the full complement of chromosomes are
present.
Spreader-sticker -
substances added to pesticides to make them spread over and stick to a
surface more readily.
Spur - on
grapevines, canes pruned to 1 to 4 nodes.
Square-foot gardening
- a system of gardening developed by Mel Bartholomew that uses 4 foot by
4 foot plots subdivided into 1-foot squares for growing a specific
number of a particular type of vegetable to maximize space and
facilitate ease of maintenance.
Stake - a piece of
pointed wood or metal that is driven into the ground to support a plant.
Stamen - the male
part of the flower. It consists of the anther and the slender filament
that holds it in position.
State specialists -
professors at landgrant universities who provide expertise for Extension
workers.
Stem - the main
trunk of a plant. It develops buds and shoots.
Stigma - the part of
the pistil that receives the pollen grains; usually the top of the
pistil.
Stock plant - a
plant used as a source for cuttings.
Stomata - an opening
or pore in leaves that is surrounded by guard cells.
Strain - a subgroup
of a species; the descendants of a common ancestor.
Stratification -
storing of seeds at low temperatures under moist conditions in order to
break dormancy.
Style - the slender
part of a pistil between the stigma and the ovary.
Succession planting
- planting portions of a crop over a period of time to get a continuous
harvest over a long period of time.
Succulent - having
tender, new growth or thick, fleshy tissues which store water, such as
cactus.
Sucker - a shoot
arising from the root or lower part of the stem of a plant.
Sunscald - plant
injury caused by exposure to bright sunlight, excessive heat and/or
wind.
Susceptible host -
an organism that can be infected by a pathogen.
Swale -
a low-lying or depressed and often wet stretch of land; also :
a shallow depression on a golf fairway or green .
Symbiotic -
a relationship in which two or more dissimilar organisms live together in
close association.
Symptom - evidence
of disease or damage.
Synthetic -
substances produced by chemical or biochemical means.
Systemic - a group
of pesticides that are absorbed into the tissues of plants, thereby
poisoning the organisms that feed on the plant.
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