NUTRIENT DEFICIENCY PROBLEM SOLVER
-TO USE THE PROBLEM-SOLVER, SIMPLY START AT #1
BELOW. WHEN YOU THINK YOU'VE FOUND THE PROBLEM,
READ THE NUTRIENTS SECTIONS TO LEARN MORE ABOUT
IT. DIAGNOSE CAREFULLY BEFORE MAKING MAJOR
CHANGES.
1)
If the problem
affects only the bottom or middle of the plant go to #2. b) If it affects only
the top of the plant or the growing tips, skip to #10. If the problem seems
to affect the entire plant equally, skip to #6.
2)
Leaves are a uniform yellow or light green; leaves die & drop; growth is
slow. Leaf margins are not curled-up noticeably. >> Nitrogen (N) deficiency.
b) If not, go to #3.
3) Margins of the leaves are turned up, and the
tips may be twisted. Leaves are yellowing (and may turn brown), but the veins
remain somewhat green. >> Magnesium (Mg) deficiency. b) If not, go to
#4.
4) Leaves are browning or yellowing. Yellow, brown,
or necrotic (dead) patches, especially around the edges of the leaf, which may
be curled. Plant may be too tall. >> Potassium (K) deficiency. b) If not,
keep reading.
5) Leaves are dark green or red/purple. Stems and
petioles may have purple & red on them. Leaves may turn yellow or curl under.
Leaf may drop easily. Growth may be slow and leaves may be small. >> Phosphorus
(P) deficiency. b) If not, go to #6.
6)
Tips of leaves are yellow, brown, or dead. Plant otherwise looks healthy &
green. Stems may be soft >> Over-fertilization (especially N), over-watering,
damaged roots, or insufficient soil aeration (use more sand or perlite. Occasionally
due to not enough N, P, or K. b) if not, go to #7.
7) Leaves are curled under like a ram's horn, and
are dark green, gray, brown, or gold. >> Over-fertilization (too much
N). b) If not, go to #8…
8) The plant is wilted, even though the soil is
moist. >> Over-fertilization, soggy soil, damaged roots, disease; copper
deficiency (very unlikely). b) If not, go to #9.
9) Plants won't flower, even though they get 12
hours of darkness for over 2 weeks. >> The night period is not completely
dark. Too much nitrogen. Too much pruning or cloning. b) If not, go to #10...
10) Leaves are yellow or white, but the veins are
mostly green. >> Iron (Fe) deficiency. b) If not, go to #11.
11) Leaves are light green or yellow beginning
at the base, while the leaf margins remain green. Necrotic spots may be between
veins. Leaves are not twisted. >> Manganese (Mn) deficiency. b) If not,
#12.
12) Leaves are twisted. Otherwise, pretty much
like #11. >> Zinc (Zn) deficiency. b) If not, #13.
13) Leaves twist, then turn brown or die. >>
The lights are too close to the plant. Rarely, a Calcium (Ca) or Boron (B) deficiency.
b) If not… You may just have a weak plant.
NUTRIENTS
Nitrogen
- Plants need lots of N during vegging, but it's easy to overdo it. Added too
much? Flush the soil with plain water. Soluble nitrogen (especially nitrate)
is the form that's the most quickly available to the roots, while insoluble
N (like urea) first needs to be broken down by microbes in the soil before the
roots can absorb it. Avoid excessive ammonium nitrogen, which can interfere
with other nutrients. Too much N delays flowering. Plants should be allowed
to become N-deficient late in flowering for best flavor.
Magnesium - Mg-deficiency is pretty common since
marijuana uses lots of it and many fertilizers don't have enough of it. Mg-deficiency
is easily fixed with ¼ teaspoon/gallon of Epsom salts (first powdered and dissolved
in some hot water) or foliar feed at ½ teaspoon/quart. When mixing up soil,
use 2 teaspoon dolomite lime per gallon of soil for Mg. Mg can get locked-up
by too much Ca, Cl or ammonium nitrogen. Don't overdo Mg or you'll lock up other
nutrients.
Potassium - Too much sodium (Na) displaces K, causing
a K deficiency. Sources of high salinity are: baking soda (sodium bicarbonate
"pH-up"), too much manure, and the use of water-softening filters
(which should not be used). If the problem is Na, flush the soil. K can get
locked up from too much Ca or ammonium nitrogen, and possibly cold weather.
Phosphorous - Some deficiency during flowering is normal, but too much shouldn't be tolerated. Red petioles and stems are a normal, genetic characteristic for many varieties, plus it can also be a co-symptom of N, K, and Mg-deficiencies, so red stems are not a foolproof sign of P-deficiency. Too much P can lead to iron deficiency.
Iron
– Fe is unavailable to plants when the pH of the water or soil
is too high. If deficient, lower the pH to about 6.5 (for rockwool, about 5.7),
and check that you’re not adding too much P, which can lock up Fe. Use
iron that’s chelated for maximum availability. Read your fertilizer’s
ingredients – chelated iron might read something like “iron EDTA”.
To much Fe without adding enough P can cause a P-deficiency.
Manganese – Mn gets locked out when the pH
is too high, and when there’s too much iron. Use chelated Mn.
Zinc – Also gets locked out due to high pH.
Zn, Fe, and Mn deficiencies often occur together, and are usually from a high
pH. Don’t overdo the micro-nutrients-lower the pH if that’s the
problem so the nutrients become available. Foliar feed if the plant looks real
bad. Use chelated zinc.
Check Your Water – Crusty faucets and shower
heads mean your water is “hard,” usually due to too many minerals.
Tap water with a TDS (total dissolved solids) level of more than around 200ppm
(parts per million) is “hard” and should be looked into, especially
if your plants have a chronic problem. Ask your water company for an analysis
listing, which will usually list the pH, TDS, and mineral levels (as well as
the pollutants, carcinogens, etc) for the tap water in your area.
This is a common request, especially in this day and age, so it shouldn’t raise an eyebrow.
Regular water filters will
not reduce a high TDS level, but the costlier reverse-osmosis units, distillers,
and de-ionizers will. A digital TDS meter (or EC = electrical conductivity meter)
is an incredibly useful tool for monitoring the nutrient levels of nutrient
solution, and will pay for itself before you know it. They run about $40 and
up.
General
Feeding Tips - Pot plants are very adaptable, but a general rule of thumb
is to use more nitrogen & less phosphorous during the vegetative period,
and the exact opposite during the flowering period. For the veg. period try
a N:P:K ratio of about 10:7:8 (which of course is the same ratio as 20:14:16),
and for flowering plants, 4:8:8. Check the pH after adding nutrients. If you
use a reservoir, keep it circulating and change it every 2 weeks. A general
guideline for TDS levels is as follows:
seedlings = 50-150 ppm; unrooted clones = 100-350 ppm; small plants = 400-800
ppm; large plants = 900-1800 ppm; last week of flowering = taper off to plain
water. These numbers are just a guideline, and many factors can change the actual
level the plants will need. Certain nutrients are "invisible" to TDS
meters, especially organics, so use TDS level only as an estimate of actual
nutrient levels. When in doubt about a new fertilizer, follow the fertilizer's
directions for feeding tomatoes. Grow a few tomato or radish plants nearby for
comparison.
PH -
The pH of water after adding any nutrients should be around 5.9-6.5 (in rockwool,
5.5-6.1). Generally speaking, the micro-nutrients (Fe, Zn, Mn, Cu) get locked
out at a high pH (alkaline) above 7.0, while the major nutrients (N, P, K, Mg)
can be less available in acidic soil or water (below 5.0). Tap water is often
too alkaline. Soils with lots of peat or other organic matter in them tend to
get too acidic, which some dolomite lime will help fix. Soil test kits vary
in accuracy, and generally the more you pay the better the accuracy. For the
water, color-based pH test kits from aquarium stores are inexpensive, but inaccurate.
Invest in a digital pH meter ($40-80), preferably a waterproof one. You won't
regret it.
Cold - Cold weather (below 50F/10C) can lock up
phosphorous. Some varieties, like equatorial sativas, don't take well to cold
weather. If you can keep the roots warmer, the plant will be able to take cooler
temps than it otherwise could.
Heat - If the lights are too close to the plant,
the tops may be curled, dry, and look burnt, mimicking a nutrient problem. Your
hand should not feel hot after a minute when you hold it at the top of the plants.
Raise the lights and/or aim a fan at the hot zone. Room temps should be kept
under 85F (29C) -- or 90F (33) if you add additional CO2.
Humidity - Thin, shriveled leaves can be from low
humidity. 40-80 % is usually fine.
Mold and Fungus - Dark patchy areas on leaves and
buds can be mold. Lower the humidity and increase the ventilation if mold is
a problem. Remove any dead leaves, wherever they are. Keep your garden clean.
Insects
- White spots on the tops of leaves can mean spider mites
underneath.
Sprays
- Foliar sprays can have a "magnifying glass" effect under bright
lights, causing small white, yellow or burnt spots which can be confused with
a nutrient problem. Some sprays can also cause chemical reactions.
Insufficient light - tall, stretching plants are
usually from using the wrong kind of light. Don't use regular incandescent bulbs
("grow bulbs") or halogens to grow cannabis. Invest in fluorescent
lighting (good) or HID lighting (much better) which supply the high-intensity
light that cannabis needs for good growth and tight buds. Even better, grow
in sunlight.
Clones - yellowing leaves on unrooted clones can be from too much light, or the stem may not be firmly touching the rooting medium. Turn off any CO2 until they root. Too much fertilizer can shrivel or wilt clones - plain tap water is fine.
HEAT
STRESS
Look closely below, and you'll see the brown leaf edges that are indicative of heat stress. This damage looks a lot like nutrient burn, except it occurs only at the tops of the plants closest to the lamps. There's only one cure for this...get the heat away from the plants, either by moving the lamps or moving the plants.
Figure 1
NUTRIENT
SOLUTION BURN
There's a good chance that this leaf was subjected to nutrient solution burn. These symptoms are seen when the EC concentration of hydroponic solutions is too high. These symptoms also appear when strong nutrient solution is splashed onto the leaves under hot HID lamps, causing the leaves to burn under the solution.
Figure 2
Many hydroponic gardeners see this problem. It's the beginning of nutrient burn. It indicates that the plants have all the nutrients they can possibly use, and there's a slight excess. Back off the concentration of the nutrient solution just a touch, and the problem should disappear. Note that if the plants never get any worse than this leaf (figure 3), then the plants are probably just fine. Figure 4 is definitely an over-fert problem.
The high level of nutrients accumulates in the leaves and causes them to dry out and burn up as shown here. You must flush with clear, clean water immediately to allow the roots to recover, and prevent further damage. Now find the cause of the high nutrient levels.
- Figure 3 -Figure 4
OVERWATERING
The plants in figure 5 were on a continous drip system, where nutrient solution
is constantly being pumped into the medium. This tends to keep the entire root
system completely saturated. A better way would be to periodically feed the
plants, say for ½ hour every 2-3 hours. This would give the roots a chance
to get needed air to them, and prevent root rot and other problems.
Don’t be throw off by the fact that the plants in figure 5 are sitting
in still water, this is actually an H2O2 solution used to try and correct the
problem. Adding an airstone to the tub would also help add O2 to the solution.
Figure 5
PH FLUCTATION
Both of these leaves in figure 6 and figure 7 are from the same plant. It could be over fertilization, but more likely it is due to the pH being off. Too high or too low a pH can lock up nutrients in the form of undisolvable salts and compounds, some of which are actually toxic to the plants. What then happens is the grower then tries to supplement the plants diet by adding more fertilizers, throwing off the pH even more and locking up even more nutrients. This type of problem is seen more often in soil mixes, where inconsistent mixing of the medium's components leads to "hot" spots.
-Figure 6 -Figure 7
OZONE DAMAGE
Ozone damage typically found near the generator. Although a rare problem, symptoms generally appear as a Mg deficiency, but the symptoms are localized to immediately around the generator.
Figure 8
NUTRIENT PROBLEMS
ROOT STUNTING
Root stunting is characteristic
of calcium deficiency, acidity, aluminum toxicity, and copper toxicity. Some
species may also show it when boron deficient. The shortened roots become thickened,
the laterals become stubby, peg-like, and the whole system often discolors,
brown or grey.
Symptoms localized at shoot growing points.
New shoots unopened; young leaves distorted; dead leaf tips; pale green plant
copper deficiency
New shoots withered or dead; petiole or stem collapse; shoots stunted; green
plant calcium deficiency Young leaves pale green or yellow; rosetting or dead
tip; dieback; dark green plant boron deficiency
MOBILE ELEMENTS
Mobile elements are more likely
to exhibit visual deficiencies in the older leaves, because during demand these
elements will be exported to the new growth.
Nitrogen
(N)
Nitrate - Ammonium is found in both inorganic and organic forms in the plant,
and combines with carbon, hydrogen, oxygen and sometimes sulfur to form amino
acids, amino enzymes, nucleic acids, chlorophyll, alkaloids, and purine bases.
Nitrogen rates high as molecular weight proteins in plant tissue.
Plants need lots of N during vegging, but it's easy to overdo it. Added too
much? Flush the soil with plain water. Soluble nitrogen (especially nitrate)
is the form that's the most quickly available to the roots, while insoluble
N (like urea) first needs to be broken down by microbes in the soil before the
roots can absorb it.
Avoid excessive ammonium nitrogen,
which can interfere with other nutrients.
Too much N delays flowering. Plants should be allowed to become N-deficient
late in flowering for best flavor.
Nitrogen Deficiencies:
Plants will exhibit lack of vigor, slow growth and will be weak and stunted.
Quality and yield will be significantly reduced. Older leaves become yellow
(chlorotic) from lack of chlorophyll. Deficient plants will exhibit uniform
light green to yellow on older leaves, these leaves may die and drop. Leaf margins
will not curled up noticeably. Chlorosis will eventually spread throughout the
plant. Stems, petioles and lower leaf surfaces may turn purple
Figure 9
Figure 10
As seen in figure 10 consumption of nitrogen (N) from the fan leaves during the final phase of flowing is 100% normal.
Nitrogen
Toxicity:
Leaves are often dark green and in the early stages abundant with foliage. If
excess is severe, leaves will dry and begin to fall off. Root system will remain
under developed or deteriorate after time. Fruit and flower set will be inhibited
or deformed.
With breakdown of vascular tissue restricting water uptake. Stress resistance
is drastically diminished.
Phosphorus
(P)
Phosphorus is a component of certain enzymes and proteins, adenosine triphosphate
(ATP), ribonucleic acids (RNA), deoxyribonucleic acids (DNA) and phytin. ATP
is involved in various energy transfer reactions, and RNA and DNA are components
of genetic information.
Phosphorus (P) deficiency:
Figure 11 is severe phosphorus (P) deficiency during flowering. Fan leaves are
dark green or red/purple, and may turn yellow. Leaves may curl under, go brown
and die. Small-formed buds are another main symptom.
Phosphorus deficiencies exhibit slow growing, weak and stunted plants with dark
green or purple pigmentation in older leaves and stems.
Some deficiency during flowering is normal, but too much shouldn't be tolerated.
Red petioles and stems are a normal, genetic characteristic for many varieties,
plus it can also be a co-symptom of N, K, and Mg-deficiencies, so red stems
are not a foolproof sign of P-deficiency. Too much P can lead to iron deficiency.
Purpling: accumulation of anthocyanin pigments; causes an overall dark green
color with a purple, red, or blue tint, and is the common sign of phosphate
deficiency.
Some plant species and varieties respond to phosphate deficiency by yellow instead of purple.(purple is natural color to some plants)
Figure 11.
Figure 12
Figure 12 shows Phosphorus (P) deficiency during vegatative growth. Many people mistaken this for a fungus, but look for the damage to occur near the end of leave, and leaves the color dull greyish with a very brittle texture
Phosphorus
(P) Toxicity:
This condition is rare and usually buffered by pH limitations. Excess phosphorus
can interfere with the availability and stability of copper and zinc.
Potassium
(K)
Potassium is involved in maintaining the water status of the plant and the tugor
pressure of it's cells and the opening and closing of the stomata. Potassium
is required in the accumulation and translocation of carbohydrates. Lack of
potassium will reduce yield and quality.
Potassium
deficiency:
Older leaves are initially chlorotic but soon develop dark necrotic lesions
(dead tissue). First apparent on the tips and margins of the leaves. Stem and
branches may become weak and easily broken, the plant may also stretch. The
plant will become susceptible to disease and toxicity. In addition to appearing
to look like iron deficiency, the tips of the leaves curl and the edges burn
and die.
Potassium - Too much sodium (Na) displaces K, causing a K deficiency. Sources
of high salinity are: baking soda (sodium bicarbonate "pH-up"), too
much manure, and the use of water-softening filters (which should not be used).
If the problem is Na, flush the soil. K can get locked up from too much Ca or
ammonium nitrogen, and possibly cold weather.
Figure 13
Figure 14
Potassium
(K) Toxicity:
Usually not absorbed excessively by plants. Excess potassium can aggravate the
uptake of magnesium, manganese, zinc and iron and effect the availability of
calcium.
Magnesium
(Mg)
Magnesium is a component of the chlorophyll molecule and serves as a cofactor
in most enzymes.
Magnesium
(Mg) deficiency:
Magnesium deficiency will exhibit a yellowing (which may turn brown) and interveinal
chlorosis beginning in the older leaves. The older leaves will be the first
to develop interveinal chlorosis. Starting at leaf margin or tip and progressing
inward between the veins. Notice how the veins remain somewhat green though
as can be seen in figure 15.
Notice how in figure 16 and 17 the leaves curl upwards like they're praying?
They're praying for Mg! The tips may also twist.
This can be quickly resolved by watering with 1 tablespoon Epsom salts/gallon
of water. Until you can correct nutrient lockout, try foliar feeding. That way
the plants get all the nitrogen and Mg they need. The plants can be foliar feed
at ½ teaspoon/quart of Epsom salts (first powdered and dissolved in some hot
water). When mixing up soil, use 2 teaspoon dolomite lime per gallon of soil.
If the starting water is above 200 ppm, that is pretty hard water, that will
lock out mg with all of the calcium in the water. Either add a 1/4 teaspoon
per gallon of epsom salts or lime (both will effectively reduce the lockout
or invest into a reverse osmosis water filter.
Mg can get locked-up by too much Ca, Cl or ammonium nitrogen. Don't overdo Mg
or you'll lock up other nutrients.
Figure 15
Figure 16
Figure 17
Magnesium
(Mg) Toxicity:
Magnesium toxicity is rare and not generally exhibited visibly. Extreme high
levels will antagonize other ions in the nutrient solution.
Zinc
(Zn)
Zinc plays a roll in the same enzyme functions as manganese and magnesium. More
than eighty enzymes contain tightly bound zinc essential for their function.
Zinc participates in chlorophyll formation and helps prevent chlorophyll destruction.
Carbonic anhydrate has been found to be specifically activated by zinc.
Zinc Deficiencies:
Deficiencies appear as chlorosis in the inter-veinal areas of new leaves producing
a banding appearance as seen in figure 18. This may be accompany reduction of
leaf size and a shortening between internodes. Leaf margins are often distorted
or wrinkled. Branch terminals of fruit will die back in severe cases.
Also gets locked out due to high pH. Zn, Fe, and Mn deficiencies often occur
together, and are usually from a high pH. Don’t overdo the micro-nutrients,
lower the pH if that’s the problem so the nutrients become available.
Foliar feed if the plant looks real bad. Use chelated zinc. Zinc deficiency
produces “little leaf” in many species, especially woody ones; the
younger leaves are distinctly smaller than normal. Zinc deficiency may also
produce “rosetting”; the stem fails to elongate behind the growing
tip, so that the terminal leaves become tightly bunched.
Figure 18
Zinc
Toxicity:
Excess Zinc is extremely toxic and will cause rapid death. Excess zinc interferes
with iron causing chlorosis from iron deficiency. Excess will cause sensitive
plants to become chlorotic.
IMMOBILE ELEMENTS
Immobile elements will show
their first symptoms on younger leaves and progress to the whole plant.
Sulphur
(S)
Sulfate is involved in protein synthesis and is part of the amino acids, cystine
and thiamine, which are the building blocks of proteins. It is active in the
structure and metabolism in the plant. It is essential for respiration and the
synthesis and breakdown of fatty acids.
Sulphur (S) deficiency:
The initial symptoms are the yellowing of the entire leaf including veins usually
starting with the younger leaves. Leaf tips may yellow and curl downward. Sulfur
deficiencies are light green fruit or younger leaves with a lack of succulence.
Elongated roots and woody stem. Although it's hard to see in figure 19, the
upper stems of this plant are purple. Although many varieties of cannabis do
get purplish stems, the trait generally extends the entire length of the plant's
stem, and not just near the top as in this specimen.
- Figure 19
Sulphur
Toxicity:
Leaf size will be reduced and overall growth will be stunted. Leaves yellowing
or scorched at edges. Excess may cause early senescence.
Calcium
(Ca)
Calcium plays an important role in maintaining cell integrity and membrane permeability.
Calcium Deficiency:
Young leaves are affected first and become small and distorted or chlorotic
with irregular margins, spotting or necrotic areas. Bud development is inhibited,
blossom end rot and internal decay may also occur and root may be under developed
or die back. Deficiency will cause leaf tip die-back, leaf tip curl and marginal
necrosis and chlorosis primarily in younger leaves. Symptoms: young leaves develop
chlorosis and distortion such as crinkling, dwarfing, developing a strap-like
shape, shoots stop growing and thicken.
Calcium Toxicity:
Difficult to distinguish visually. May precipitate with sulfur in solution and
cause clouding or residue in tank. Excess calcium may produce deficiencies in
magnesium and potassium.
Iron (Fe)
Iron is an important component of plant enzyme systems for electron transport
to carry electrons during photosynthesis and terminal respiration. It is a catalyst
for chlorophyll production and is required for nitrate and sulfate reduction
and assimilation.
Iron deficiency:
- Pronounced interveinal chlorosis similar to that caused by magnesium deficiency
but on the younger leaves.
-Leaves exhibit chlorosis (yellowing) of the leaves mainly between the veins,
starting with the lower and middle leaves.
Caused by factors that interfere with iron absorption of roots: over irrigation,
excessive soluble salts, inadequate drainage, pests, high substrate pH, or nematodes.
This is easily corrected by adding an iron supplement with the next watering.
Fe is unavailable to plants
when the pH of the water or soil is too high. If deficient, lower the pH to
about 6.5 (for rockwool, about 5.7), and check that you’re not adding
too much P, which can lock up Fe. Use iron that’s chelated for maximum
availability. Read your fertilizer’s ingredients – chelated iron
might read something like “iron EDTA”. To much Fe without adding
enough P can cause a P-deficiency.
Note: When adding iron to the solution,
it is often necessary to not use fertilizer for that watering. Iron has a tendency
of reacting with many of the components of fertilizer solutions, and will cause
nutrient lockup to occur. Read the labels of both the iron supplement and the
fertilizer you are using before you attempt to combine the two.
Iron
Toxicity:
Excess accumulation is rare but could cause bronzing or tiny brown spots on
leaf surface.
Manganese
(Mn)
Manganese is involved in the oxidation reduction process in the photosynthetic
electron transport system. Biochemical research shows that this element plays
a structural role in the chloroplast membrane system, and also activates numerous
enzymes.
Manganese Deficiency:
Interveinal chlorosis of younger leaves, necrotic lesions and leaf shredding
are typical symptom of this deficiency. High levels can cause uneven distribution
of chlorophyll resulting in blotchy appearance. Restricted growth and failure
to mature normally can also result.
-Mn gets locked out when the pH is too high, and when there's too much iron.
Use chelated Mn.
Manganese Toxicity:
Toxicity: Chlorosis, or blotchy leaf tissue due to insufficient chlorophyll
synthesis. Growth rate will slow and vigor will decline.
Chlorine (Cl)
Chloride is involved in the evolution of oxygen in the photosynthesis process
and is essential for cell division in roots and leaves. Chlorine raises the
cell osmotic pressure and affects stomata regulation and increases the hydration
of plant tissue. Levels less than 140 ppm are safe for most plants. Chloride
sensitive plants may experience tip or marginal leaf burn at concentrations
above 20 ppm.
Chlorine
Deficiency:
Wilted chlorotic leaves become bronze in color. Roots become stunted and thickened
near tips. Plants with chlorine deficiencies will be pale and suffer wilting.
Chlorine
Toxicity:
Burning of leaf tip or margins. Bronzing, yellowing and leaf splitting. Reduced
leaf size and lower growth rate.
Boron
(B)
Boron biochemical functions are yet uncertain, but evidence suggests it is involved
in the synthesis of one of the bases for nucleic acid (RNA uracil) formation.
It may also be involved in some cellular activities such as division, differentiation,
maturation and respiration. It is associated with pollen germination.
Boron
Deficiency:
Plants deficient in boron exhibit brittle abnormal growth at shoot tips and
one of the earliest symptoms is failure of root tips to elongate normally. Stem
and root apical meristems often die. Root tips often become swollen and discolored.
Internal tissues may rot and become host to fungal disease. Leaves show various
symptoms which include drying, thickening, distorting, wilting, and chlorotic
or necrotic spotting.
Boron
Toxicity:
Yellowing of leaf tip followed by necrosis of the leaves beginning at tips or
margins and progressing inward before leaves die and prematurely fall off. Some
plants are especially sensitive to boron accumulation.
Copper
(Cu)
Copper is a constituent of many enzymes and proteins. Assists in carbohydrate
metabolism, nitrogen fixation and in the process of oxygen reduction.
Copper
Deficiency:
Symptoms of deficiency are a reduced or stunted growth with a distortion of
the younger leaves and growth tip die-back. Young leaves often become dark green
and twisted. They may die back or just exhibit necrotic spots. Growth and yield
will be deficient as well.
Copper
Toxicity:
Copper is required in very small amounts and readily becomes toxic in solution
culture if not carefully controlled. Excess values will induce iron deficiency.
Root growth will be suppressed followed by symptoms of iron chlorosis, stunting,
reduced branching, abnormal darkening and thickening of roots.
Molybdenum
(Mo)
Molybdenum is a component of two major enzyme systems involved in the nitrate
reeducates, this is the process of conversion of nitrate to ammonium.
Molybdenum
Deficiencies:
Often interveinal chlorosis which occurs first on older leaves, then progressing
to the entire plant. Developing severely twisted younger leaves which eventually
die. Molybdenum deficiencies frequently resemble nitrogen, with older leaves
chlorotic with rolled margins and stunted growth.
Molybdenum
Toxicity:
Excess may cause discoloration of leaves depending on plant species. This condition
is rare but could occur from accumulation by continuous application. Used by
the plant in very small quantities. Excess mostly usually does not affect the
plant; however the consumption of high levels by grazing animals can pose problems
so she might not be too good to smoke.
Sodium
(Na)
Sodium seems to encourage crop yields and in specific cases it acts as an antidoting
agent against various toxic salts. It may act as a partial substitute for potassium
deficiencies. Excess may cause plant toxicity or induce deficiencies of other
elements. If sodium predominates in the solution calcium and magnesium may be
affected.
Silicon
(Si)
Silicon usually exists in solution as silicic acid and is absorbed in this form.
It accumulates as hydrated amorphous silica most abundantly in walls of epidermal
cells, but also in primary and secondary walls of other cells. It is largely
available in soils and is found in water as well. Inadequate amounts of silicon
can reduce tomato yields as much as 50%, cause new leaves to be deformed and
inhibit fruit set. At this time toxicity symptoms are undetermined.
Cobalt
(Co)
Cobalt is essential to many beneficial bacteria that are involved in nitrogen
fixation of legumes. It is a component of vitamin B12 which is essential to
most animals and possibly in plants. Reports suggest that it may be involved
with enzymes needed to form aromatic compounds. Otherwise, it is not understood
fully as to its benefit to plant growth, but it is considered essential to some
animal health issues.