Marijuana leaf heat stress
If you look closely you will see the brown marijuana leaf edges in the center that are indicative of marijuana leaf heat stress. This damage looks allot like nutrient burn, except marijuana leaf heat stress occurs only at the tops of the marijuana plants closest to the lamps. There's only one cure for this... get the heat away from the marijuana plants, either by moving the lamps or moving the marijuana plants.
Nutrient solution marijuana leaf burn
There's a good chance that this marijuana bud 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 marijuana leaves under hot HID lamps, causing the cannabis leaves to burn under the solution.
Many hydroponic gardeners see this problem. It's the beginning of nutrient burn. It indicates that the marijuana 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 marijuana plants never get any worse than this here, then the marijuana plants are probably just fine.
This figure is definitely an over-fertilization problem. The high level of nutrients accumulates in the marijuana 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. The find the cause of the high nutrient levels.
The marijuana plants in the first picture [marijuana leaf heat stress] were on a continuous 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 marijuana plants, say for 1/2 hour every 2 to 3 hours. This would give the marijuana 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 marijuana plants in figure 2 [nutrient solution marijuana leaf burn] are sitting in still water, this is actually an H² O² solution used to try and correct the problem. Adding an air stone to the tub would also help add O² to the solution.
The leave in this picture could be over-fertilized, 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 unsolvable salts and compounds, some of which are actually toxic to the marijuana plants. What then happens is the cannabis grower then tries to supplement the marijuana 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.
Marijuana ozone damage
Marijuana ozone damage is generally found near the generator. Although it is a rare problem, symptoms of ozone damage appears as a Magnesium [Mg] deficiency, but the symptoms are localized around the generator only. Magnesium [Mg] deficiency will exhibit a yellowing [which may turn brown] and inter vein chlorosis beginning in the older marijuana leaves. The older marijuana leaves will be the first to develop inter vein chlorosis. Starting at leaf margin or tip and progressing inward between the veins.
Marijuana root stunting
Marijuana root stunting is a characteristic of calcium [Ca] deficiency, acidity, aluminum toxicity, and copper toxicity. Some marijuana strains may also show it when boron [B] deficient. The shortened marijuana roots become thickened, the laterals become stubby, peg-like, and the whole system often discolours, brown or grey.
Symptoms localized at the marijuana shoot growing points:
- young leaves distorted, dead leaf tips, pale green marijuana plant » Copper [Cu] deficiency
- New shoots withered or dead petiole or stem collapse, shoots stunted, green marijuana plant » Calcium [Ca] deficiency
- Young leaves pale green or yellow rosetting or dead tip, dieback, dark green marijuana plant » Boron [B] deficiency
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
Nitrate - Ammonium is found in both inorganic and organic forms in the marijuana plant, and combines with carbon, hydrogen, oxygen and sometimes sulfur [S] to form amino acids, amino enzymes, nucleic acids, chlorophyll, alkaloids, and purine bases. Nitrogen [N] rates high as molecular weight proteins in marijuana plant tissue. Marijuana plants need lots of nitrogen [N] during the vegetative stage, but it's easy to overdo it. Added too much? Flush the soil with plain water. Soluble nitrogen [N] [especially nitrate] is the form that's the most quickly available to the roots, while insoluble nitrogen [N] [like urea] first needs to be broken down by microbes in the soil before the roots can absorb it. Avoid excessive ammonium nitrogen [N], which can interfere with other nutrients. Too much nitrogen [N] delays flowering. Marijuana plants should be allowed to become nitrogen [N] deficient late in flowering for best flavour.
Nitrogen [N] deficiencies
Marijuana plants will exhibit lack of vigour, slow growth and will be weak and stunted. Quality and marijuana yield will be significantly reduced. Older cannabis leaves become yellow [chlorotic] from lack of chlorophyll. Deficient marijuana plants will exhibit uniform light green to yellow on older marijuana leaves, these leaves may die and drop. Leaf margins will not curled up noticeably. Chlorosis will eventually spread throughout the marijuana plant. Stems, petioles and lower leaf surfaces may turn purple.
Nitrogen [N] toxicity
Marijuana leaves are often dark green and in the early stages abundant with foliage. If excess is severe, marijuana leaves will dry and begin to fall off. Root system will remain under developed or deteriorate after time. With breakdown of vascular tissue restricting water uptake. Stress resistance is drastically diminished.
Phosphorus [P] is a component of certain enzymes and proteins, adenosine tri-phosphate [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
Symptoms of phosphorus [P] deficiency are: marijuana fan leaves are dark green or red/purple, and may turn yellow. Leaves may curl under, go brown and die. Small formed marijuana buds are another main symptom. Phosphorus [P] deficiencies exhibit slow growing, weak and stunted marijuana plants with dark green or purple pigmentation in older marijuana 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 marijuana varieties, plus it can also be a co-symptom of Nitrogen [N] , Potassium [K], and Magnesium [Mg] deficiencies, so red stems are not a foolproof sign of phosphorus [P] deficiency. Too much phosphorus [P] can lead to iron [Fe] 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 [P] deficiency by yellowing instead of purpling. Purpling is natural to some healthy ornamentals.
This picture shows Phosphorus [P] deficiency during vegetative growth. Many people mistaken this for a fungus, but look for the damage to occur near the end of leave, and leaves the colour dull greyish with a very brittle texture.
Potassium [K] is involved in maintaining the water status of the marijuana plant, the pressure of it's cells and the opening and closing of the stomata. Potassium [K] is required in the accumulation and translocation of carbohydrates. Lack of potassium [K] will reduce marijuana yield and quality.
Potassium [K] deficiency
Older marijuana leaves are initially chlorotic but soon develop dark necrotic lesions [dead tissue]. First apparent on the tips and margins of the marijuana leaves. Stem and branches may become weak and easily broken, the cannabis plant may also stretch. The marijuana plant will become susceptible to disease and toxicity. In addition to appearing to look like iron [Fe] deficiency, the tips of the marijuana leaves curl and the edges burn and die. Too much sodium [Na] displaces potassium [K], causing a potassium [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 sodium [Na], flush the soil. Potassium [K] can get locked up from too much calcium [Ca] or ammonium nitrogen [N] and possibly cold weather.
Potassium [K] toxicity
Usually not absorbed excessively by marijuana plants. Excess potassium [K] can aggravate the uptake of magnesium [Mg], manganese[Mn], zinc [Zn], iron [Fe] and effect the availability of calcium [Ca].
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 inter vein chlorosis beginning in the older marijuana leaves. The older marijuana leaves will be the first to develop inter vein 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 in this picture. If the marijuana leaves curl upwards like they're praying... they are praying for magnesium [Mg]! The marijuana leaf tips may also twist. This can be quickly resolved by watering with one tablespoon Epsom salts on a gallon | 3.5 liters of water. Until you can correct nutrient lockout, try foliar feeding. That way the marijuana plants get all the nitrogen [N] and Magnesium [Mg] they need.
The marijuana 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 two teaspoon dolomite lime per gallon | 3.5 liters of soil. If the starting water is above 200 parts per million [ppm], that is pretty hard water, that will lock out magnesium [Mg] with all of the calcium [Ca] in the water. Either add a ¼ teaspoon per gallon \ 3.5 liters of epsom salts or lime [both will effectively reduce the lockout or invest into a reverse osmosis water filter. Magnesium [Mg] can get locked-up by too much calcium Ca, chloride [Cl] or ammonium nitrogen. Don't overdo magnesium [Mg] or you'll lock up other nutrients.
Magnesium [Mg] toxicity
Magnesium [Mg] toxicity is rare and not generally exhibited visibly. Extreme high levels will antagonize other ions in the nutrient solution.
Zinc [Zn] plays a roll in the same enzyme functions as manganese [Mn] and magnesium [Mg]. More than eighty enzymes contain tightly bound zinc [Zn] essential for their function. Zinc [Zn] participates in chlorophyll formation and helps prevent chlorophyll destruction. Carbonic anhydrate has been found to be specifically activated by zinc [Zn].
Zinc [Zn] deficiencies
Zinc [Zn] deficiencies appear as chlorosis in the inter-vein areas of new marijuana leaves producing a banding appearance as seen in the picture below. This may be accompany reduction of marijuana 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. Zinc [Zn], Iron [Fe], and Manganese [Mn] deficiencies often occur together, and are usually from a high pH. Don't overdo the micro-nutrients lower the pH if that is the problem so the nutrients become available. Foliar feed if the marijuana plant looks real bad. Use chelated zinc [Zn]. Zinc [Zn] deficiency produces "little leaf" in many species, especially woody ones; the younger leaves are distinctly smaller than normal. Zinc [Zn] deficiency may also produce "rosetting"; the stem fails to elongate behind the growing tip, so that the terminal leaves become tightly bunched.
Zinc [Zn] toxicity
Excess zinc [Zn] is extremely toxic and will cause rapid death. Excess zinc [Zn] interferes with iron [Fe] causing chlorosis from iron [Fe] deficiency. Excess will cause sensitive marijuana plants to become chlorotic.
Immobile elements will show their first symptoms on younger marijuana leaves and progress to the whole marijuana plant.
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 marijuana plant. It is essential for respiration and the synthesis and breakdown of fatty acids.
Sulphur [S] deficiency
The initial symptoms of Sulphur [S] deficiency are the yellowing of the entire marijuana leaf including veins usually starting with the younger marijuana leaves. Leaf tips may yellow and curl downward. Sulphur [S] deficiencies younger leaves with a lack of succulence. Elongated roots and woody stem. Although it is hard to see in the picture below, the upper stems of this marijuana plant are purple. Although many varieties of marijuana do get purplish stems, the trait generally extends the entire length of the marijuana plant's stem, and not just near the top as in this marijuana plant.
Sulphur [S] Toxicity
The marijuana leaf size will be reduced and overall growth will be stunted. Marijuana leaves yellowing or scorched at edges. Excess may cause early senescence.
Calcium [Ca] plays an important role in maintaining cell integrity and membrane permeability.
Calcium [Ca] deficiency
Young marijuana leaves are affected first and become small and distorted or chlorotic with irregular margins, spotting or necrotic areas. Marijuana bud development is inhibited, blossom end rot and internal decay may also occur and root may be under developed or die back. Calcium [Ca] deficiency will cause root tip die-back, marijuana leaf tip curl and marginal necrosis and chlorosis primarily in younger marijuana leaves. The symptoms of calcium [Ca] deficiency are: young marijuana leaves develop chlorosis and distortion such as crinkling, dwarfing, developing a strap-like shape, shoots stop growing and thicken.
Calcium [Ca] toxicity
Difficult to distinguish visually. May precipitate with sulfur [S] in solution and cause clouding or residue in tank. Excess calcium [Ca] may produce deficiencies in magnesium [Mg] and potassium [K].
Iron [Fe] is an important component of marijuana 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, sulfate [S] reduction and assimilation.
Iron [Fe] deficiency
Pronounced inter-vein chlorosis similar to that caused by magnesium [Mg] deficiency but on the younger marijuana leaves. Leaves exhibit chlorosis [yellowing] of the marijuana leaves mainly between the veins, starting with the lower and middle marijuana leaves. Caused by factors that interfere with iron [Fe] absorption of roots: over irrigation, excessive soluble salts, inadequate drainage, pests, high substrate pH, or nematodes. This is easily corrected by adding an iron [Fe] supplement with the next watering. Iron [Fe] is unavailable to cannabis plants when the pH of the water or soil is too high. If deficient, lower the pH to about 6.5 [for rock wool, about 5.7], and check that you are not adding too much phosphorus [P], which can lock up iron [Fe]. Use iron [Fe] that' is chelated for maximum availability. Read your fertilizer's ingredients - chelated iron [Fe] might read something like "iron EDTA". To much iron [Fe] without adding enough phosphorus [P] can cause a phosphorus [P] deficiency.
When adding iron [Fe] to the solution, it is often necessary to not use fertilizer for that watering. Iron [Fe] 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 [Fe] supplement and the fertilizer you are using before you attempt to combine the two.
Excess accumulation is rare but could cause bronzing or tiny brown spots on marijuana leaf surface.
Manganese [Mn] 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 [Mn] deficiency
Inter-vein chlorosis of younger marijuana leaves, necrotic lesions and leaf shredding are typical symptom of manganese [Mn] deficiency. High levels can cause uneven distribution of chlorophyll resulting in blotchy appearance. Restricted growth and failure to mature normally can also result. Manganese [Mn] gets locked out when the pH is too high, and when there's too much iron. Use chelated manganese [Mn].
Manganese [Mn] toxicity
Chlorosis, or blotchy marijuana leaf tissue due to insufficient chlorophyll synthesis. Marijuana growth rate will slow and vigour will decline.
Chloride [Cl] is involved in the evolution of oxygen in the photosynthesis process and is essential for cell division in marijuana roots and leaves. Chlorine [Cl] raises the cell osmotic pressure and affects stomata regulation and increases the hydration of marijuana plant tissue. Levels less than 140 parts per million [ppm] are safe for most plants. Chloride sensitive plants may experience tip or marginal leaf burn at concentrations above 20 parts per million [ppm].
Chlorine [Cl] deficiency
Wilted chlorotic marijuana leaves become bronze in colour. Roots become stunted and thickened near tips. Marijuana plants with chlorine [Cl] deficiencies will be pale and suffer wilting.
Chlorine [Cl] toxicity
Burning of marijuana leaf tip or margins. Bronzing, yellowing and leaf splitting. Reduced marijuana leaf size and lower growth rate.
Boron [B] 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 [B] deficiency
Marijuana plants deficient in boron [B] exhibit brittle abnormal growth at shoot tips and one of the earliest symptoms is failure of root tips to elongate normally. Marijuana stem and root apical stems often die. Root tips often become swollen and discolored. Internal tissues may rot and become host to fungal disease. Marijuana leaves show various symptoms which include drying, thickening, distorting, wilting, and chlorotic or necrotic spotting.
Boron [b] toxicity
Yellowing of marijuana leaf tip followed by necrosis of the marijuana leaves beginning at tips or margins and progressing inward before marijuana leaves die and prematurely fall off. Some plants are especially sensitive to boron [B] accumulation.
Copper [Cu] is a constituent of many enzymes and proteins. Assists in carbohydrate metabolism, nitrogen [N] fixation and in the process of oxygen reduction.
Copper [Cu] deficiency
Symptoms of copper [Cu] deficiency are a reduced or stunted growth with a distortion of the younger marijuana leaves and growth tip die-back. Young marijuana leaves often become dark green and twisted. They may die back or just exhibit necrotic spots. Growth and cannabis yield will be deficient as well.
Copper [Cu] toxicity
Copper [Cu] is required in very small amounts and readily becomes toxic in solution culture if not carefully controlled. Excess values will induce iron [Fe] deficiency. Marijuana root growth will be suppressed followed by symptoms of iron [Fe] chlorosis, stunting, reduced branching, abnormal darkening and thickening of marijuana roots.
Molybdenum [Mb] is a component of two major enzyme systems involved in the nitrate reeducates, this is the process of conversion of nitrate to ammonium.
Molybdenum [Mb] deficiencies
Often inter-vein chlorosis which occurs first on older marijuana leaves, then progressing to the entire marijuana plant. Developing severely twisted younger marijuana leaves which eventually die. Molybdenum [Mb] deficiencies frequently resemble nitrogen [N], with older marijuana leaves chlorotic with rolled margins and stunted growth.
Molybdenum [Mb] toxicity
Excess may cause discoloration of leaves on the marijuana plant . This condition is rare but could occur from accumulation by continuous application. Used by the marijuana plant in very small quantities. Excess mostly usually does not effect the marijuana plant, however the consumption of high levels by grazing animals can pose problems so she might not be too good to smoke.
Silicon [Sid] 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 marijuana yields as much as 50%, cause new marijuana leaves to be deformed. At this time toxicity symptoms are undetermined.
Silicon [Si] deficiency
The effects of silicon [Si] deficiency are: affects the development of strong leaves, stems, and roots, affects the formation of a thick silicated epidermal cell layer and reduces photosynthetic activity. The symptoms of silicon [Si] deficiency: soft and droopy marijuana leaves, increased occurrence of diseases and smaller marijuana yields.
Cobalt [Co] is essential to many beneficial bacteria that are involved in nitrogen [N] fixation of marijuana plants. Cobalt [Co] is a component of vitamin B12 which is essential to most animals and possibly in marijuana plants. Reports suggest that it may be involved with enzymes needed to form aromatic compounds. Otherwise, it is not understood fully as to it's benefit to marijuana plant growth, but it is considered essential to some animal health issues.