Hydroponic Index
http://www.gchydro.com/glossary.asp
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 http://www.gchydro.com/glossary.asp
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Hydroponic Glossary
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A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
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Absorption
Uptake
of nutrients from the soil by plant roots, or directly into the leaves from
foliar sprays.
Acid
A
sour substance. Refers to medium or nutrient solution with a low pH; an
acidic solution has a pH below 7.
Aeration
Supplying
soil and roots with air or oxygen.
Aeroponics
A system in which the roots of a plant are consistently or intermittently
misted with fine droplets of nutrient solution.
Alkaline
Refers
to medium or nutrient solution with a high pH. Any pH over 7 is considered
alkaline.
Aero-Hydroponics
A method of growing that uses rockwool, net pots,
vine clips, or other devices to support the plant while its roots grow in the
air with a constant mist of nutrient solution. Growing plants in this method
of oxygen infused into the nutrient solution allows roots to absorb nutrients
faster and easier therefore providing rapid growth and fantastic yields.
Aeroponics
Aeroponics is a
form of hydroponics. The roots of the growing plants are suspended in the
air, and they are misted by high pressure sprayers. The sprayers break the
nutrient into small particles and saturate the roots. The levels of oxygen in
the water are kept high by the constant circulation of the water. Experiments
with aeroponics have shown that plants can grow up
to 50% faster than in regular hydroponic systems.
Algal Bloom
Exaggerated algal growth due to oversupply of nutrients in the waterway.
Anther
The pollen-bearing part of the stamen.
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Bacteria
Extremely small, one-celled organisims that don't have chlorophyll.
Bacterial soft rot
See Botrytis.
Ballast
The electrical components that energize a high intensity bulb. (Typically a
transformer or a capacitor)
Beneficial Insect
An insect that eats bad flower and vegetable eating insects.
Beneficiation
The process of removing clay and other impurities from phosphate rock to
enhance the phosphorus content of the rock.
Biodegradable
Capable of being decomposed by
biological agents, especially bacteria.
Bloom Booster (Blossom Booster)
Fertilizer high in phosphorus (P) that
increases flower yield.
Bolting
When a plant prematurely begins the development of a flowering stalk, and,
subsequently, seed.,
Boron (B)
The function of this micronutrient is not well understood, but it is
suspected that it might aid carbohydrate transport.
Botrytis
Any of various fungi of the genus Botrytis responsible for numerous
diseases of fruits and vegetables; often referred to as bacterial soft rot or
gray mold.
Buffering
The ability of a substance to reduce shock and provide cushion against pH flucuations.
Buffer Solutions
Buffers are solutions that have
constant pH values and the ability to resist changes in the pH level. They
are used to calibrate the pH measurement system (electrode and meter) Buffers
are available with a wide range of pH values, and they come in both premixed
liquid form or as convenient dry powder capsules.
Burn
Leaf tips that turn dark from excess fertilizer and salt burn.
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Calcium (CA)
Calcium is vital in all parts of plants to promote the translocation of
carbohydrates, healthy cell wall structure, strong stems, membrane maintenance,
and root structure development. Calcium is a macronutrient
Carbon Dioxide (CO2)
A colorless, odorless, tasteless gas in the air necessary for plant life.
Occurs naturally in the atmosphere at .03%.
Capillary action
A phenomenon associated with surface tension and resulting in the elevation
or depression of liquids in capillaries. This is similar to the manner in
which plants seem to defy gravity when they transport liquid upwards from
their roots.
Caton Exchange Capacity
A measure of soil's ability to hold positively charged nutrient ions for
plant use.
CF:
Conductive factor (See Conductivity)
Chelate
Combining nutrients in an atomic ring
that is easy for plants to absorb.
Chlorine (Cl)
This micronutrient is essential for photosynthesis, where it acts as an enyzme activator during the production of oxygen from
water.
Cholorphyll
Any of a group of related green pigments found in photosynthetic cells that
converts light energy into ATP and other forms of energy needed for
biochemical processes; it is found in green plants, brown and red algae, and
certain aerobic and anaerobic bacteria.
Chlorosis
The condition of a sick plant with yellowing leaves due to inadequate
formation of chlorophyll. Chlorosis is caused by a
nutrient deficieny, usually iron or nitrogen;
nutrient deficiencies are themselves often caused by a pH that is out of the
acceptable range.
Clone
A plant produced through asexual reproduction including, but not limited to,
cuttings, layering, and tissue culture.
Closed System
A hydroponic system, like nutrient film technique
(NFT) systems, that recirculates the nutrient
solution.
C/N Ratio
Carbon-to-nitrogen ratio in soil. Provides a measure of the quality and rate
of decomposition of organic matter. The lower the ration, the quicker the
organic matter will break down, and release nutrients in forms available for
plant uptake.
Color Temperature
The relative color of light emitted by a lamp. An example is a piece of red
hot iron emits a red glow which has a low color temperature. A piece of hite hot iron emits a glow with more blue light, which
makes the color more white, and a higher color temperature. The unit of
measure for color temperature is called "Kelvin" and is expressed
in degrees Kelvin.
Conditioning
To soak new Rockwool in an acidic solution to lower the pH from 8.0 to 5.5
Conductivity
The scale used to measure the strength of nutrient solution. Pure water
doesn't conduct any electricity but as you dissolve mineral salts in the
water you increase Conductivity. More salts, stonger
solution, higher Conductivity.
Copper (Cu)
This micronutrient is an internal catalyst and acts as an electon
carrier, it is also believed to play a role in nitrogen fixation.
Cross-Pollination
The transfer of pollen from an anther of the flower of one plant to a stigma
of the flower of another plant.
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Damping-off Fungus
Disease that attacks young seedlings and cuttings, causing stems to rot at
the base; overwatering is the main cause of
damping-off.
Deficiency
A lack or shortage, especially of something essential to health; an
insufficiency: a nutritional deficiency. When a plant's nutrient uptake is
deficient it is evidenced by visual symptoms such as, but not limited to,
changes in color, malformed leaves, and dying leaves.
Denitrification
The loss or removal of nitrogen or nitrogen compounds; specifically
: reduction of nitrates or nitrites commonly by bacteria (as in soil)
that usually results in the escape of nitrogen into the air. Often occurs in
waterlogged soils.
Dioecious Of or relating to
organisms, especially plants, having the male and female reproductive organs
borne on separate individuals of the same species; sexually distinct.
Dissolved Solids
The amount of dissolved solids, usually fertilizer salts, that are measured
in water in parts per million.
Drip Aeration
A hydroponic
method wherein air pressure from a small air pump is used to percolate
nutrient solution out through a ring of feeder tubing which encircles the
plant.
Drip System (Drip Emitter System) A very efficient watering
system that employs a main hose with small water emitters. Water is metered
out of the emitters, one drop at a time.
Dry Rot
See Fusarium
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Ebb and flow
The term "Ebb and Flow" simply means a method of irrigation that
completely floods the growing media root zone, then lets the water drain away
from the root zone, back to the reservoir. It is also called the "Flood
and Drain" method by some growers.
E.C.
Electrical conductivity See Conductivity
Eutrophication
Having waters rich in mineral and organic nutrients that promote a
proliferation of plant life, especially algae, which reduces the dissolved
oxygen content and often causes the extinction of other organisms
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F1, F2, F3, etc
The F1 generation is the result of crossing two different varieties; a cross
of two F1 plants produces F2 seed; and so on.
Fertilizer Burn
Over fertilization: identified by
leaves first turing yellow (burning) then curling.
Fertilizer
Any of a large number of natural and
synthetic materials, including manure and nitrogen, phosphorus, and potassium
compounds, spread on or worked into soil to increase its capacity to support
plant growth.
Filament
The stalk that bears the anther in a
stamen. See Stalk
Fixation
The process by which
available plant nutrients become unavailable by reaction with
components of the soil.
Foliar Feeding
Misting plants with fertilizer
solution, which is absorbed by the foliage.
Footcandle
The
amount of light that illuminates 1 square foot of surface area, one foot in
distance from the candle.
Fungicide
A product that destroys or inhibits
fungus.
Fungus
Any of a major group (Fungi) of
saprophytic and parasitic spore-producing organisms usually classified as
plants that lack chlorophyll and include molds, rusts, mildews, smuts,
mushrooms, and yeasts. Common fungal diseases that attack plants are
"damping-off," Botrytis, and powdery mildew.
Fusarium
A form genus of fungi (family Tuberculariaceae) including important plant pathogens and
several infectious agents that afflict plants, commonly referred to as dry rot
or wilt
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Geolite
One of several brand names/varieties of clay aggregate medium (also known as
LECA for light expanded clay aggregate). It is a lightweight, porous
substrate with excellent aeration. Because it does not really wick water
effectively, Geolite and other LECA mediums are
favorites in ebb-and-flow and drip hydroponic
systems.
Germination
The process of causing the intiation and
development of a plant from a seed.
Gray
Mold
See Botrytis
Growing
Medium
Materials occasionally used in hydroponic growing
to support a plant's roots and, sometimes, to hold nutrient.
Gypsum
Hydrated calcium sulfate, used as a soil conditioner. It can be mined from
natural sources or produced as a by-product when manufacturing phosphoric
acid, if obtained in that manner it's known as phosphogypsum.
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Harden-Off
To gradually acclimatize a plant to a more harsh
environment. A seedling must me hardened-off before planting outdoors.
H.I.D. (High Intensity Discharge) Lights
Lights that produce very intense light using an electric arc with metallic
vapor inside a quartz arc tupe surrounded by a
glass outer bulb that prevents ultraviolet rays from being radiated. These
horticultural lights produce 5-6 times as much light compared to incandescent
lights of the same wattage and last 10-30 times as long. These durable
systems have a life span of 15+ years.
Hormone
Chemical substance that controls the growth and development of a plant.
Root-inducing hormones help cuttings root.
Humidity (Relative)
The ratio of water vapor density (mass per unit volume) to the saturation
water vapor density. Basically the ratio between the amount of moisture in
the air and the amount of moisture the air could hold at that same
temperature.
Humus
A brown or black organic substance consisting of partially or wholly decayed
vegetable or animal matter that provides nutrients for plants and increases
the ability of soil to retain water.
Hybrid
The offspring from two plants of different breeds, variety, or genetic
make-up.
Hyrdrated Lime
Instantly soluble lime, used to raise or lower pH.
Hygrometer
An instrument for measuring relative humidity in the atmosphere.
Hydrogen Peroxide (H2O2)
A clear sharp smelling substance very similar in appearance to water. Like
water it is made up of Hydrogen and Oxygen, however
H2O2 has an extra Pxygen atom in an unstable
arrangement. It is this extra atom that gives H2O2 it's
useful properties. Hydrogen is useful in hydroponics for pretreating
water.
Hydroponics
Cultivation of plants in nutrient solution rather than in soil.
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Inbred
(True Breed)
Offspring of plants of the same breed or ancestry
Inert
Chemically non-reactive; inert growing mediums make it easy to control the
chemistry of the nutrient solution.
Inline Fans
Inline fans have the motor and blade inside a housing that's usually
circular. They are useful for moving air from one room to another, or through
walls, or ceilings to outside. They may be used with short lengths of ducting
to control direction of air flow. These are the most commonly used fans for
exhaust vents, at the top of the growing area. This draws out the hot, stale
air. Inline fans have the advantage of being thin. They may be place directly
into walls or ceilings. They may also be used to send air through short
lengths of ducting.
Insects
There are several types of insects that attack plants. These include; aphids,
caterpillars, cutworms, fungus gnats, leaf miners, nematodes, spider mites, thrips, and whiteflies.
Intensity
The magnitude of the light energy per unit; intensity diminishes the farther
away from the source.
Iron (Fe)
This micronutrient acts as a catalyst in the photosynthesis/respiration
process, and is essential for the formation of sugars and starches. Iron also
activates certain other enzymes.
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Jacket
The protective outer bulb or envelope of lamp.
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Kelvin
A unit of measurement for expressing the heat or light given off by an
object. At zero degrees Kelvin no molecules would be moving and no heat or light given off. Natural sunlight is 5500
degrees Kelvin. Light that has less blue will have a lower Kelvin
temperature.
Kilowatt Hour
Measure of electricity used per hour; a 1000-watt HID uses one kilowatt in
one hour
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Labile
Open to change; adaptable, describes a soil nutrient which may become
available for plant uptake.
Lacewing
Beneficial insects that prey on aphids
Leach
Dissolve or wash out soluble components of soil by heavy watering.
Leaching
Washing of nutrients through the soil to a depth beyond the root zone of
plants.
Leaf Curl
Leaf malformation due to over-watering, over fertilization, lack of
magnesium, insect or fungus damage, or negative tropism.
Leaf Mold
See Cladosporium
Leaflet
Small immature leaf
Leggy
Abnormally tall internode space, with sparse
foliage. Legginess of a plant is usually caused by
a lack of blue light or CO2. It can also be caused by too much nitrogen.
Lifecycle
A series of growth stages through which a plant must pass in its natural
lifetime; the stages for an annual plant are seed, seedling, vegetative, and
floral.
Light mover
A device that moves a lamp back and forth across or in a circle around the
ceiling of a garden room to provide more even distribution of light.
Lime
Used in the form of dolomite or hydrated lime to raise and stabilize soil pH.
Litmus Paper
Chemically sensitive paper used for testing pH. The paper is chemically
treated in such a way that when dipped into a water sample it will change
color to indicate the pH level.
Loam
Organic soil mixture of crumbly clay, silt, and sand.
Lumen
The amount of light emitted by a candle at a distance of 1 foot from the
candle.
Lumens per Watt
The lumen output of a lamp, divided by the input wattage.
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Macronutrients
The primary nutrients consisting of nitrogen (N), phosphorus (P), potassium
(K), and sulfur (S) or the secondary nutrients magnesium (Mg) and calcium
(Ca).
Manganese (Mn)
This micronutrient activates one ore more enzymes in fatty acid synthesis; it
also activates the enzymes resonsible for DNA and
RNA production. Closely associated with copper and zinc, manganese also
participates directly in the photosynthetic creation of oxygen from water.
Medium
The substrate or soilless material which supports
the plant and absorbs and releases the nutrient solution in hydroponic horticulture.
Micronutrients
Also referred to Trace Elements. They are the minor minerals used in
small amounts by plants consisting of boron (B), copper (Cu), cobalt (Co),
iron (Fe), manganese (Mn), molybdenum (Mo), and
zinc (Zn).
Mineral Deficiency
Lack of a mineral micronutrient that is essential for normal nutrition or
metabolism. When a plant is not receiving a required nutrient, either all or
an insufficient amount, a disorder will result.
Mineralization
The process carried out by soil micro-organisims
whereby nutrients are released in an inorganic form from the decomposition of
organic material.
Mobile Nutrients
The nutrients that move freely with soil moisture, or can be moved within the
plant from older tissues. Some nutrients can immobile in soils and mobile in
plants, and vice versa.
Molybdenum (Mo)
Micronutrient essential for nitrogen fixation and nitrate reduction.
Monoecious
Varieties or species with seperate male and female
flowers on each plant.
Mulch
A protective covering, usually of organiz matter
such as leaves, straw, or peat, placed around plants to prevent the
evaporation of moisture, the freezing of roots, and the growth of weeds.
Mylar
A metallic film that is similar to a
paper thin mirror that is either taped or tacked to the walls in a growing
area.
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Nanometer
The unit of length equal to one
billionth of a meter. It is used to measure the spectrum of light colors.
Blue light has a shorter wavelength than red light
Necrosis
The dying of plant tissue, usually the result of serious nutrient deficiency
or pest attack.
Nitrogen (N)
Nitrogen is used in various forms to promote rapid vegetative growth, leaf,
flower, fruit, and seed development, and chlorophyll development; and to
increase the protein content in plants.
Nitrification
The process by which soil organisms use oxygen to convert ammonium ions to
nitrate ions.
Nitrogen (N)
Nitrogen is used in various forms to promote rapid vegetative growth, leaf,
flower, fruit, and seed development, and chlorophyll development; and to
increase the protein content in all plants.
Non-labile
A soil nutrient which is tied up in the soil and unavailable for plant
uptake.
Nutrient Film Technique (NFT)
A hydroponic method in which nutrient is fed into
grow tubes or trays in a thing film where roots draw it up. This
"nutrient film" allows the roots to have constant contact with the
nutrient and the air layer above at the same time.
Nutrient Solution
The mixture of water and water-soluble nutrients which is provided to the
plants for nourishment in a hydroponic system.
Nutrients
Elements such as nitrogen and iron that are needed for plant growth and
health.
Nutrients, Secondary
The elements other than N, P, and K which are considered nearly as important
as N, P, and K but are not considered micronutrients. Calcium (Ca), magnesium
(Mg), and sulphur (S) are the elements usually
referred to by this term.
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Oscillating
Fans
These are the same type of fans used for room air movement. There are special
wall mount horticultural oscillating fans. These are best for sending waves
of fresh Carbon Dioxide charged air to the plant leaves. The oscilliation feature sends new air across the complete
growing area. The important thins is to keep bringing fresh air in contact
with the leaves of the plants.
Osmosis
The diffusion of fluid through a semipermeable
membrane seperating a solvent and a solution to
bring about a condition of equilibrium.
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Parts
Per Million (PPM)
The ratio figure that represents the amount of one substance that is in one
million parts of another substance; often used to describe the relative
concentrations of nutrient solutions.
PAR
Photosynthetically Active Radiation, the part of
the sunlight spectrum that plants use
Passive
A hydroponic system without a pump. The plants take
up nutrients through a fibrous wick from the pot to the nutrient solution.
Perlite
A white, grasslike volcanic mineral, about
one-tenth the weight of sand, that is useful as a medium for rooting cuttings
but lacks any nutrients.
pH
The pH scale is a way to measure the Acid or Akaline
qualities of water. The offical definition of pH
is: a unit of measure which describes the degree of acidity, or alkalinity of
a solution. It is measured on a scale of 0-14. The term pH is dervied from "p" the mathematical symbol of the
negative logarithm, and "H", the chemical symbol of Hydrogen. The folrmal definition of pH is the negative logarithm of the
Hydrogen ion activity {pH=-log[H=]}. pH expresses the degree of an activity of an acid or base
in terms of hydrogen ion activity. In general,plants grow best in a pH range of 6 to 6.8; 6.3 is
considered ideal. If the pH is not within the acceptable range, nutrients may
not be absorbed to maxium capacity.
Photoperiod
The duration of an organism's daily exposure to light, considered especially
with regard to the effect of the exposure on growth and development.
Phosphorus (P)
Phosphorus promotes and stimulates early growth, blooming, and root growth.
It hastens maturity and seed growth, and contributes to the general hardiness
of plants. Phosphorus is a macronutrient.
Photosynthesis
The process in green plants and certain other organisms by which
carbohydrates are synthesized from carbon dioxide and water using light as an
energy source. Most forms of photosynthesis release oxygen as a byproduct.
Pistil
The female, ovule-bearing organ of a flower, including the stigma, style, and
ovary.
Pollen
The fine powderlike material, consisting of pollen
grains, that is produced by the anthers of seed plants.
Pollination
The carrying of pollen grains to the female sex cells for fertilization.
Potassium (K)
Potassium promotes disease resistance and good development of carbohydrates,
starches, and sugars. It also increases fruit production. Potassium is a
macronutrient.
Propagate
1.Sexual: To produce seed by breeding different male and female flowers. 2.
Asexual: To produce plantlets (also known as clones) by taking cuttings.
Pyrethrum
Natural insecticide made from the blossoms of various chrysanthemums.
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Resevoir
The container in a hydroponic system which holds nutrient
solution in reserve for use.
Reverse Osmosis
The process of removing minerals from water by pushing a solution through a
filter that traps the solute on one side and allows the pure solvent to be
obtained from the other side.
Rockwool
Inert, soilless growing medium consisting of woven,
thin strand-like fibers made from molten volcanic rock and limestone, which
is heated to over 2900 degrees farenheit, extruded,
and formed into slabs, cubes, and blocks.
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Sailine Soil
Soil which affects plant growth due to high levels of salinity. Normally
associated with sodium choloride.
Salt Index
The measure of the ratio of change in osmotic pressure caused by different
fertilizers. A fertilizer with a high salt index may cause damage to when
applied near or directly to seeds.
Secondary Nutrients
Calcium (Ca) and magnesium are considered to be the secondary nutrients.
Side-dress
To apply granular fertilizer to the soil alongside a plant or row of plants
during the growing season to stimulate them.
Sodic soil
Soil where the structure has been affected by high concentrations of exchangable sodium.
Soil Fertility
The status of soil in regards to the amount and availability of essential
nutrients.
Split Application
Splitting the seasonal fertilizer requirement into a number of smaller
applications. This technique is commonly used for nitrogen and potassium,
which are subject to loss through leaching.
Stalk
A stem or similar structure that supports a plant part such as a flower,
flower cluster, or leaf. On a male flower it is the portion of the stamen
that supports the anther.
Stamen
The pollen-producing organ of a flower, usually consisting of a filament and
an anther.
Sterilization
The state or condition of being free from microorganisms. In hydroponics it
is essential that all materials being used are sterile to avoid contamination
of the hydroponic system.
Stigma
The receptive apex of the pistil of a flowe, on
which pollen is deposited at in pollination.
Style
The usually slender part of a pistil, situated between the ovary and the
stigma.
Systemic
Used in reference to a disease within the plant tissue, not intiated from the external cells. Also refers to
materials and compounds which are taken up or absorbed by the plant and
designed to fight disease (e.g. systemic fungicide).
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Tap
Root
The main or primary root that grows from the seed; lateral roots will branch
off the tap root.
Transformer
A device in the ballast that transforms electric power from one voltage to
another.
Transpire
Give off water vapor and by products via stomata and carbon dioxide intake at
the leaves.
Trellis
Frame of small boards (lattice) that trains or supports plants.
Top-dressed
Uniform broadcast application of fertilizer to the soil surface after a crop
or pasture has become established.
Tungsten
A heavy, hard metal with high melting point which conducts electricity well;
tungsten is used for a filament in tungsten halogen and incandescent lamps.
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Ultraviolet
Light with very short wave lengths, out of the visible spectrum past the
blue-violet
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VAM
(Vesicular sbuscular mycorrhiza)
A soil fungus that attacks the roots of some plants and assists in the uptake
of phosphorus and other immobile nutrients
Vermiculite
Mica which has been processed and expanded by heat. Vermiculite has excellent
water retention qualities and is a good soil amendment and medium for rooting
cuttings
Volatilization
The process by which certain soluble soil nutrients are changed from solid or
aqueous forms to gaseous forms and are lost from the soil to the atmosphere.
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Watts per Square Foot
The wattage of a lamp, divided by the size of the coverage area.
Wick
Part of passive hydroponic system using a wick
suspended in the nutrient solution. The nutrients pass up the wick and are
absorbed by the medium and roots.
Wilt
Any plant disease characterized by drooping and shriveling; usually caused by
parasites attacking the roots.
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Zinc (Zn)
Like copper and manganese, zinc is linked to chlorophyll synthesis.
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Strawberries need one year or longer
to mature from seed. Try and find a cutting to propagate. Also try to get a
self pollinating variety. They require a high level of light for 16 - 18 hours
per day. Any standard hydroponic nutrient should be
sufficient.
Strawberries grow well hydroponicaly,
I tried it myself with very good results! I used Rockwool as a growing medium
and a flood and drain system.
Nutrients http://www.gchydro.com/art_Mantra.asp Some mineral-based nutrients are slightly better than others
depending on the source of the nutrients.
Flushing Program http://www.hydroponics.com.au/back_issues/issue37.html "Unless
you keep a good regular program of flushing, there is a build-up of salts, not
just of sodium and chloride, but potassium and nitrogen as well," observed
Keith.
Beneficial
Bacteria
In the early days, Keith and Vivian thoroughly cleaned
the lettuce system between crops; anything they could do to minimise
the transfer of disease was no effort. But all that stopped 3 years ago when
they started using Amnite 100, a blend of 23 beneficial bacterial and
fungal organisms.
Beneficial
bacterial and fungal organisms are marketed in Australia under different names
including Amnite 100, Get-Back-Teria,
Ag-Bact L, Organosol and
OGP, among others. Initially, it was used as a foliar spray, and put through
the lettuce root zone, but Keith found the foliar spray caused too much
bacteria on the leaves of the lettuce. He now restricts the friendly micro-organism
to the root zone. For the flower crop, Keith uses the micro-organisms as a
foliar spray, rather than through the roots where they tend to block the
drippers.
"One
very clear problem that it cleared up amongst the flowers is botritus, and whenever I don't have enough bacteria, the botritus returns," commented Keith. According to
Keith, the
'friendlies' make the nutrients in the solution more
available to plants, however he warns that the micro-organisms will not work
properly outside of certain temperature parameters, or if there's not enough
oxygen in the system.
"I
have found it definitely works for me, and we've found certain ways to apply it
which helps it to work better, added Keith.
Gravel Filtration System
The lettuce system incorporates a fast-flowing gravel
filtration system. Using a 1000 litre fibreglass tank, the filter consists of a series of
different size gravels, from fine through to coarse grade. An inlet pipe
extends across the diameter of the gravel filter, its underside peppered with large
holes to disperse the nutrient solution across the breadth of the gravel
filter, at a rate of 3 litres per second. The inlet
pipe is covered with a 'pantyhose' stocking to act as a fine filter. The filter
system is used to distribute the beneficial micro-organisms throughout the
system.
"The
gravel filter is an excellent area for the bacteria to exist," Keith
explains, "and I feel I'm getting the same type of result as the sand filtration
system (Practical Hydroponics & Greenhouses - September/October 1995 -
Issue #24), but at a much faster rate."
Testimony
to the health of the biofilter is evidenced by the
colony of worms that live within the gravel.
"People
say that inorganic fertilisers are not in 'sync' with
normal biosystems, but to find worms in the gravel
filter indicates to me that it is a very healthy system," commented Keith.
Conclusion
Although there has been little scientific work done to
support the claims of products such as Amnite 100,
there is a wealth of anecdotal evidence to suggest these products deserve
closer scrutiny.
The
symbiotic relationship between plant root systems and beneficial bacteria and
fungi is widely recognised by many horticulture
growers. It is now understood that there are extensive interrelationships
between micro-organisms and plant roots. Some examples include seed innoculants which are used to sow legumes to provide
nitrogen fixing bacteria for their roots; the use of beneficial fungi like actinomycetes spp, which are used
as an adjuvant to fertilisers applied to fields; and vescular arbuscular mycorrihizae (VAM), which plays a critical role in helping
plant roots extract nutrients from depleted soils.
It is known that crops like lettuce, grown in recirculating NFT systems, eventually accumulate large
populations of pathogens such as Fusarium, Pythium spp and Verticillium spp. They cause
destruction of roots and leaves, leading to plant death. In some horticultural applications, treatment often involves
the use of agricultural surfactants, which are used to suppress the
development/reproduction of such pathogens. However, surfacants
are not registered in New South Wales
for use in hydroponic nutrient solutions, with the
exception of Agral 500.
Surfactants
mimic the hormone oestrogen. When they get into the
aqueous environment, they contaminate marine and riverine
animal species causing males to lose their ability to produce testosterone,
thereby having a feminising effect. This problem has
been clearly demonstrated in the Florida Everglades where alligators are
failing to reproduce.
Medical
scientists know that our intestines are full of millions of bacteria, which are
responsible for many of the reactions that occur during digestion. They assist
us in assimilating the nutrients in our food. It is now recognised
that as
we age, it is harder to maintain the population of friendlies
in our gut. A depletion of beneficial bacteria leads to replacement and colonisation by harmful bacteria and fungi. An example is candida albicans, a harmful fungus that lives in the gut, producing
harmful toxins that circulate in the bloodstream. This is why we are encouraged to eat yogurt daily, to
replenish the friendly bacteria and maintain the balance.
Much
work still needs to be done to fully understand the complex interrelationships
between friendly micro-organisms and plants. Although controlled scientific
experiments using products such as Amnite 100 have so
far proved inclonclusive, strong anecdotal evidence
suggests that these organisms seem to play an important role in the control and
prevention of plant disease in hydroponic
applications. 
There has been considerable interest in the use of baking soda (sodium
bicarbonate, NaHCO3) and potassium bicarbonate (KHCO3) to
control powdery mildew and other fungal diseases of plants. This publication
provides a brief survey of observations, research, and recommendations on the
use of bicarbonates in horticulture.
The use of baking soda as a fungicide is not a new idea. In Alfred C. Hottes' A Little Book
of Climbing Plants, published in 1933 by the A.T. De La Mare Co. of
New York,
mention is made of using one ounce of baking soda per gallon of water to
control powdery mildew (PM) on climbing roses. The author credits the idea to a
Russian plant pathologist, A. de Yaczenski.(1)
In the August, 1985 issue of Organic
Gardening magazine, a short article by Warren Shultz entitled
"Recipe for Resistance" reports that researchers in Japan obtained
effective control of PM on cucumbers, eggplants, and strawberries. They
suggested weekly sprays of ¼ ounce baking soda per gallon of water.(2)
An article in the June, 1990 issue of Greenhouse
Manager magazine summarizes the results of three years of testing
baking soda as a fungicide for roses. Cornell
University researcher Dr. R. Kenneth
Horst observed suppression of PM and blackspot—both
major problems for New York
rose growers. Roses
were sprayed every 3 to 4 days with a water solution of baking soda and
insecticidal soap. The latter was included for its surfactant
qualities. (Surfactants are chemical agents that alter the surface properties
of a liquid.) The soap improved the effectiveness of the bicarbonate by making
it stick to, and spread evenly over, the leaf surface. Further experimentation
proved that the insecticidal soap itself was not responsible for suppressing
the diseases. While no specific concentration of baking soda is indicated as
being most effective in PM suppression, the article states that a 0.5% solution was
most effective in preventing blackspot.(3)
Some of the work at Cornell has focused on controlling fungal diseases on
cucurbits.(4)
A single spray application (to runoff) of 0.5% (wt./vol.
of water) baking soda, plus 0.5% (vol./vol. of water)
SunSpray UFP® horticultural oil almost completely
inhibited PM on heavily infected pumpkin foliage. Baking soda without spray oil was ineffective,
and a 2% (wt./vol. of water)
solution of baking soda damaged the leaves. Baking soda/oil sprays also
provided good control of urocladium leaf spot in
cucumber, alternaria leaf blight in muskmelon, and
gummy stem blight in muskmelon.(5) Other
diseases against which baking soda may prove effective include anthracnose in
cucurbits (6);
rust, dollar spot, and pythium blight in turf; late
blight in potato; rust in wheat; and diseases affecting peanuts, banana, and
alfalfa.(7)
Researchers in Israel reported the successful use of baking soda and SunSpray oil in controlling PM on euonymus.(8) In this
research a 2% baking soda and 1% oil solution proved most effective.(9)
On-farm observations on melon acreage in Virginia resulted in one farm operation
switching from synthetic fungicides to a baking soda/oil spray. These growers
incorporated a liquid fertilizer into the mix.(10)
Research in Germany
evaluated baking soda as a control for PM on `Bacchus' grapes. Three spray
applications were made, beginning when symptoms first appeared. Good control
was achieved with no loss of grape quality. The optimum concentration was a 1%
solution.(11)
An article in the February, 1996 issue of GrowerTalks magazine follows up on
the continuing research at Cornell. Testing with a variety of bicarbonates
revealed that selecting the correct bicarbonate for a particular disease is
important. Dr. Horst's research team found that ammonium bicarbonate had the
strongest effect on some diseases, while potassium and sodium bicarbonates
worked best against others. Potassium bicarbonate provided the best control of
PM. "Sodium bicarbonate is okay, but it's not as good," Horst is
quoted as saying. "And ammonium bicarbonate doesn't do the job on powdery mildew."
He points out that while conventional chemical controls for PM are
preventatives only, bicarbonates can eliminate the disease after it has already
appeared on certain crops—he mentions roses and an unspecified
ornamental—provided the infection is not severe. The only plant damage
associated with bicarbonates applied in the trials was foliar burning when
application rates exceeded recommended concentrations. Testing established that
sodium bicarbonate does not increase the levels of sodium in plant tissues,
soil, or runoff water. While their precise mode of action against fungi is not
understood, Horst states that bicarbonates seem to damage the cell wall
membrane in PM spores. He also believes pH to be a factor in bicarbonate
effectiveness. In any case, bicarbonates are contact fungicides, and kill PM
within minutes.(7)
The Federal EPA ruled (as of December, 1996) that sodium and potassium
bicarbonates are exempt from residue tolerances.(12) This
action served to facilitate the development and release of commercial
bicarbonate products for horticultural use. It also lent weight to the belief
that these materials are largely innocuous from a food safety perspective.
Connecticut
researchers evaluated the effects of a spray solution containing 1% each of
baking soda and horticultural oil on PM infection in zucchini, pumpkin, and
cantaloupe. Four applications were made and disease suppression was definitely
observed, accompanied by reduced insect pest damage. These researchers maintain
that the treatment is preventative—not curative; that it is only
necessary in years where early outbreaks may threaten yields; and that spraying
should accompany proper nutrition and water management.(13)
In 1998, Church & Dwight Co. (14)—the manufacturer
of Arm & Hammer™ baking soda—received EPA registration for Armicarb 100®, a potassium bicarbonate formulation, for use
against PM, downy mildew, botrytis, and alternaria
leaf-spot.(15)
This product is the direct result of Dr. Horst's research at Cornell, which was
funded by Church & Dwight. Armicarb 100 is now
available from Helena Chemical Company.(16) A
similar product is sold under the name FirstStep® by
the W.A. Cleary Chemical Co.(17)
The EPA and the California Department of Environmental Protection have
provided registration to Monterey Chemical Co. (18) for a
product called Kaligreen®. A potassium bicarbonate
fungicide for PM control, it is cleared for use on grapes, cucumbers, tobacco, roses,
strawberries, and a wide range of other crops.(19, 20, 21)
Directions for use include the addition of a sticker-spreader surfactant and a
caution against use in acidic spray mixes. Since the product contains 30%
potassium it is also touted for its fertilizer value.(22) One
source of Kaligreen® is Peaceful Valley Farm Supply.(23)
Yet another potassium bicarbonate product, Remedy®, by Bonide™
(24), is
now available from Gardener's Supply Co.(25) This
formulation, which includes a surfactant oil, is labeled for use on ornamental,
nut, and fruit trees, shrubs, and many vegetable plants. Said to control PM,
black spot, leaf spot, anthracnose, phoma, phytophthora, scab, botrytis, and many other diseases,
Remedy is particularly targeted toward rose growers.(26)
Various carbonates and bicarbonates have been proven effective against gray
mold, the number one post-harvest disease of grapes. Researchers found that
carbonates were more effective than bicarbonates at reducing gray mold (Botrytis cinerea)
spore germination, and that sodium and ammonium bicarbonates were better than
potassium bicarbonate.(27)
While industry was in the process of developing bicarbonate products for
commercial and home horticulture, a number of recommendations for using
kitchen-grade baking soda surfaced in print. These include:
- J. Howard Garrett—a
well-known horticultural columnist and radio personality in the Dallas,
Texas, area—recommends baking soda sprays at a concentration of 4
teaspoons per gallon of water for control of PM, blackspot,
brown patch, and other fungal diseases. He also suggests that a light soil
spray of baking soda solution can suppress fungus gnat problems, while
cautioning that overuse should be avoided because of possible negative
effects (sodium accumulation and alkaline pH) on the soil.(28)
- The authors of an organic
pest control handbook suggest the same concentration mixture as Garrett,
but advise the addition of an equal quantity of liquid dish soap or
insecticidal soap as a surfactant.(29)
- The P. Allen Smith Gardens
website advises mixing 1 heaping tablespoon of baking soda, 1 tablespoon
of dormant oil, and ½ teaspoon of insecticidal or dish soap in one gallon
of water as a PM spray. Stating that plants should be well hydrated prior
to spraying, this source recommends irrigating a couple days in advance.(30)
References
1. Williams, Greg and Pat Williams. 1993. Baking soda vs.
powdery mildew: Not a new idea!
HortIdeas.
June. p. 62.
2. Williams, Greg and Pat Williams. 1985. Baking soda for
powdery mildew control. HortIdeas. September. p. 101-102.
3. Anon. 1990. Baking soda can ward off fungus. Greenhouse Manager.
June. p. 24.
4. Ziv, O. and T. A. Zitter. 1992. Effects of bicarbonates and film-forming
polymers on cucurbit foliar diseases. Plant Disease. Vol. 26, No. 5. p. 513-517.
5. Williams, Greg and Pat Williams. 1992. More on baking
soda/horticultural oil vs. fungal disease. HortIdeas. June. p. 69.
6. Hofstetter, Bob. 1993. Homemade
pesticides. The New Farm. February.
p. 14-16.
7. Moore, Sallyann Roberts. 1996.
Bicarbonates offer effective disease control. Grower Talks.
February. p. 72.
8. Ziv, O. and A. Hagiladi. 1993. Controlling powdery mildew in euonymus with
polymer coatings and bicarbonate solutions. HortScience. Vol. 28, No. 2. p. 124-126.
9. Williams, Greg and Pat Williams. 1993. Baking soda and
horticultural oil vs. powdery mildew. HortIdeas. May. p. 51.
10. Byczynski, Lynn. 1995. New
ideas for a new year. Growing for Market. January. p. 1, 4-5.
11. Williams, Greg and Pat Williams. 1997. Sodium
bicarbonate for control of mildew on grapes. HortIdeas. June. p. 70.
12. Otten, Paul. 1997. Can kitchen
products control powdery mildew? Northland Berry News. Fall. p.
20.
13. Elmer, Wade H. and Frank J. Farandino.
1997. Managing powdery mildew of cucurbits. The Natural
Farmer. Summer. p. 26-27.
14. Church & Dwight Co., Inc.
469 N. Harrison St.
Princeton, NJ 08543-5297
609-683-5900
800-221-0453
15. Anon. 1998. EPA approves reduced-risk fungicide. The Grower. December. p. 8.
16. Helena Chemical Co.
225 Schilling Blvd. Suite 110
Collierville, TN 38017
901 537-7280
www.helenachemical.com/sales.html
Armicarb® is available in 5 and 25 lb.
bags, for about $5/lb. Call the number above or visit the website to locate the
Helena Chemical dealer nearest you.
17. W. A. Cleary Chemical Co.
1049 Corporate Rt. 27
Somerset, NJ
08875
800-524-1662
FirstStep® is available in 5 lb. bags and
20 lb. cases. Call the number above for price information.
18. Monterey Chemical Co.
P. O. Box 35000
Fresno, CA 93745-5000
559-499-2100
www.montereychemical.com
Kaligreen is available in 5lb. and 10lb.
bags. Prices vary from dealer to dealer.
19. Anon. 1998. Powdery mildew fungicide.
The Grower. March. p. 6.
20. Anon. 1999. EPA expands Kaligreen
label. The Grower. August. p. 10.
21. Anon. 2000. Label Changes (Kaligreen) American Vegetable Grower. March. p. 14.
22. Anon. 1998. Peaceful Valley Farm Supply 1998-1999 Main
Catalog. Peaceful Valley Farm Supply. Grass Valley, CA. p. 92.
23. Peaceful Valley Farm Supply
P. O. Box 2209
Grass Valley, CA
95945
530-272-4769
888-784-1722
www.groworganic.com
24. Bonide Products, Inc.
Oriskany,
NY 13424
315-736-8231
25. Gardener's Supply Co.
128 Intervale
Rd.
Burlington, VT 05401-2850
800-863-1700
www.gardeners.com
e-mail: info@gardeners.com
26. Anon. 1998. Fungus remedy.
B.U.G.S. Flyer. Vol. 12, No. 1. p.
5.
27. Anon. 1999. Baking soda and gray mold.
Conference notes: ESA and APS joint meeting. IPM Practitioner. April. p. 10-11.
28. Garrett, J. Howard. 1989. J. Howard Garrett's Organic
Manual. Lantana Publishing Co. Dallas,
TX. 104 p.
29. Ellis, Barbara W. and Fern Marshall Bradley. 1992. The
Organic Gardener's Handbook of Natural Insect and Disease Control. Rodale
Press. Emmaus, PA. 534 p.
30. Anon. 1997. Garden lore—Baking
soda solution. P. Allen
Smith Gardens.
Hortus Ltd.
www.pallensmith.com/report_library/archive/347_baking-soda.html.
By George Kuepper,
Raeven Thomas, and Richard Earles
NCAT Agriculture Specialists
Copyright © 2001 National Center for
Appropriate Technology
IP130
Slot 102
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