Phosphorus deficiency guide

Phosphorus (K) deficiency guide

Phosphorus plays an important role for all living organisms and is an essential nutrient element for plants and animals. It has a key position in the combustion processes of the cell, and in the total energy transfer of the plant. It is also a “building block” of the cell walls, the DNA, and all sorts of proteins and enzymes.

For young plants, the presence of phosphate is indispensable; about 3/4 of the phosphorus consumed during a plant’s life cycle is absorbed in the first quarter of its life. The largest concentrations of phosphorus are found in the developing parts of the plant: the roots, the growth shoots and the vascular tissue.

About phosphorus in short

What is it and what does it do?: Phosphorus holds a key position in both cell processes and total energy transfer of the plant.; Also a “building block” of – among others – cell walls and DNA.

What can you see?: Small plant with purple/black necrotic leaf parts.; Leafs become malformed and shriveled.

What can you do?: Mix inorganic phosphate fertilizer THOROUGHLY through the potting mix or add extra liquid phosphate when growing in hydroponics.

Symptoms of a deficiency

Plants remain rather small with purple-black necrotic leaf parts, which later on become malformed and shriveled.

Development of a deficiency

At first, the plant becomes dark green – a different sort of dark green (blue/ green) as appears when there is a shortage of phosphorus.
The growth in height, and the development of the plant’s side shoots are inhibited.
After 2 to 3 weeks, dark purple-black necrotic spots appear on the old and medium-old leaves, making the leaves malformed.
The purple/black necroses expand to the leaf’s stem. The leaf turns, curls considerably and dies off.
The dead leaves are curled and shriveled, have a typical orange purple color, and fall off.
The plant flowers fully, but the yield will be minimal.

Reasons for a deficiency

Due to the low concentrations in which phosphate appears in nature, the affinity of plant cells for phosphorous allows easy absorption through the whole root. Therefore, shortages do not happen very often, except when:

The growing medium has a too high pH (higher than pH 7). In such cases the plant can not absorb phosphorus due to the fact that insoluble phosphorous compounds develop.
The ground is too acidic, or too rich in iron and zinc. This hinders the absorption of phosphate.
The potting mix has become fixated. Phosphate can not be absorbed any more.

Solutions to a deficiency

Always use inorganic phosphates as these are easy to absorb. Also always mix the phosphate fertilizer thoroughly through the potting mix.

When pH is too high, acidify the medium by using a thinned solution of phosphoric acid.
Choose products that have a guaranteed phosphate percentage on the packaging instead of alternative phosphate-containing products like guano or manure.

Thrips – Pest

Thrips – Pests & Diseases

Thrips are recognizable by their small size and long flat shape. The adult thrips has four feathery wings. They can vary in color from gray to yellow or brown. Thrips are carriers of viruses, mainly of the genus Tospovirus. These viruses cause significant crop loss and are incurable.

About the pest in brief

What are Thrips?: When we use the term thrips, we are referring to a wide group of insects of the order Thysanoptera.

What can you see?: Because certain toxic substances are present in the saliva of thrips, you may see some deformations in the shoots or flowers of the affected plants.

What can you do?: Spray plants with ecological insecticides like potassium soap or plant extracts with pyrethrum.

Biological cycle of thrips

The first stage of the thrips’ life cycle is the egg, which will hatch much more quickly when temperatures are higher. The females lay eggs in plant tissues. The larvae that emerge from the eggs feed on the surrounding tissues. One of the characteristics of these insects is that they make the transition from pupa to adult in the soil or in the lower leaves. The larvae live in the leaves, but as soon as they reach the right stage of development, they fall to the ground or lower leaves where they live during the pre-pupal and pupal stages until a reproductive adult appears with fully developed wings. The whole life cycle lasts only a few weeks.

Thrips

Symptoms of the pest

The adult thrips eats a varied diet based mainly on pollen, but the larvae feed on plant tissues and it is the larvae that are responsible for the majority of plant damage. The larvae suck the liquid from plant cells, mainly from the leaves, but also the petals, shoots and fruits. Early symptoms include an almost transparent or clear discoloration of the leaf with black dots (which are caused by fecal secretions). They have rasping, sucking mouthparts that look like combs and make a soup from the tissue which is then sucked up. Usually the top layer of the tissue is undisturbed and a window of clear tissue is seen in the middle of the area of discoloration.

Because certain toxic substances are present in the saliva of thrips, some deformations may occur in the shoots or flowers of affected plants. In cases of very severe infestation, the leaves may dry up entirely. At the same time, some thrips like Frankliniella occidentalis secrete a few drops of a substance when they are threatened by predators. These excretions contain decyl acetate and dodecyl acetate – pheromones that serve as a warning signal for other nearby thrips.

How to prevent the pest?

Because of the thrips’ ability to transmit viruses, it is important to monitor our crops for thrips and detect them as early as possible. The classic method for doing this is by using adhesive traps. These traps are blue in color, because thrips are strongly attracted to blue. The traps should be examined every few days using a magnifying glass to see if any thrips (usually winged adults) have gotten stuck to them.

Thrips

Solutions for controlling the pest

If you detect thrips, appropriate treatments need to be administered to minimize the risk of an infestation. These treatments include ecological insecticides such as potassium soap or plant extracts with pyrethrum, in places where these are allowed by law. Plants must be sprayed thoroughly all over because the thrips will take refuge under the veins of the leaves, making it difficult for the insecticide to come into contact with all the insects.

It is also possible to use entomophagous fungi to combat thrips. Beauveria bassiana is one fungi that is typically used to combat thrips. It is also important to make sure that you clean up and remove any plant or soil residues from the floor or worktops.

Aphids – Pest

Aphids

Aphids are no longer than about 4 mm, have a bulbous abdomen, and can be many different colors. They are among the most destructive pests to affect cultivated plants in temperate regions. Winged aphids are especially dangerous for your crops since they destroy plants much faster than regular aphids.

What are aphids?: When we refer to aphids or plant lice, we usually mean a superfamily of insects that includes over 4.000 species of plant-specific parasites.

What can you see?: Aphids can cause decreased growth rates, mottled leaves, yellowing, stunted growth, curled leaves, browning, wilting, low yields, and death in plants.

What can you do?: There are several cultivation techniques that we can use to prevent or minimize an attack by aphids.

Biological cycle of aphids

Aphids can be winged or wingless. Usually, the first generation to hatch after winter is wingless. However, after several generations, there can be a lack of space on the host plant. This triggers the birth of a generation of winged aphids, which can migrate to other hosts. All the aphids born from the winter eggs are females. Several more generations of female aphids are born during spring and summer. Females can live for 25 days, during which they can each produce up to 80 new aphids. Spring and summer reproduction occurs asexually – without males.

Symptoms of the pest

The aphids feed on phloem sap, which weakens the plant and causes a metabolic imbalance, twisting of the leaves and, in extreme cases, causing leaf loss. Leaf loss affects the quantity and quality of the final harvest. Aphids also introduce toxins into the plant, systemically altering its development.

Furthermore, the honeydew secreted by the aphids is an ideal culture medium for a range of various fungi, which form a barrier on the leaf, stopping it from taking in all the light that hits it.

However, the most harmful effect of aphids is the transmission of viruses. Aphids can transmit dozens of viruses from a diseased plant to a healthy one in just a few seconds, especially the winged generations. The biggest problem with viruses is that there is no remedy for them, so the infection of a plant that is not tolerant or resistant to the virus leads inevitably to a decline in the final production.

CONTROL AND PREVENTION

HOW TO GET RID OF APHIDS

Try spraying cold water on the leaves, sometimes all aphids need is a cool blast to dislodge them.
If you have an aphid invasion, dust plants with flour. It constipates the pests.
Use commercially available biological controls or spray with insecticidal soap or horticultural oil.
You can often get rid of aphids by wiping or spraying the leaves of the plant with a mild solution of water and a few drops of dishwashing detergent such as Ivory.
Stir together 1 quart of water, 1 tsp of liquid dish soap, and a pinch of cayenne pepper. Do not dilute before spraying on plants.
Organic controls include soapy emulsion, horticultural oil (read the directions), and pyrethrum spray. Soapy water should be reapplied every 2-3 days for 2 weeks.
Use homemade garlic or tomato-leaf sprays.

There are several cultivation techniques that we can use to prevent or minimize the infestation of aphids.

These include:

Eliminating weeds that can serve as a reservoir of eggs and adults
Using insect nets (sometimes insecticide-impregnated) to cover crops
Avoiding the excessive use of nitrogenous fertilizer
Removing crop residues
Establishing plant species that can serve as a reservoir for predators (banker plants)

PREVENT APHIDS

For fruit or shade trees, spray dormant oil to kill overwintering eggs.
You can purchase beneficial insects, such as lady beetles, lacewings, and parasitic wasps, which will feed on aphids. These are usually ordered via mail—check the Internet for labs. They should keep the aphid populations controlled in the first place.
- You can also plant flowering groundcovers in home orchards to attract predators.
Companion planting can be very helpful to keep aphids away from your plants in the first place. For example:
- Aphids are repelled by catnip.
- Aphids are especially attracted to mustard and nasturtium. You can plant these near more valuable plants as traps for the aphids.
- Nasturtiums spoil the taste of fruit tree sap for aphids and will help keep aphids off broccoli.
- Garlic and chives repel aphids when planted near lettuce, peas, or rose bushes.

Solutions for controlling the pest

The natural enemies of aphids include ladybird beetles (or ladybugs) and lacewings. Green lacewing larvae (Chrysoperla sp.) are voracious predators of aphids.

Fungus Gnats – Pest

The adult fungus gnat is a small black fly, about 3-4 mm in length. They are commonly seen swarming in greenhouses because they are attracted by the humidity, high temperatures and decomposing organic matter. Crop substrates offer ideal conditions for their larvae, which are white and legless, resembling small worms. They feed on organic matter and the tender parts of plants below the ground, such as roots, as well as the stems.

About the pest in brief

What are fungus gnats?: Fungus gnats (families Mycetophilidae and Sciaridae) are a common pest affecting indoor plants, especially where humidity and moisture levels are high.

What can you see?: They’re usually first noticed when the harmless adults are seen flying around house plants or gathered at a nearby window.

What can you do?: Make sure that air is circulating over the top of your soil and water your plants properly.

Biological cycle of fungus gnats

Adults live about one week and lay up to 300 eggs in rich, moist soils. Within 4-6 days tiny larvae emerge and begin feeding on plant roots during their two-week lives. The pupal stage lasts 3-4 days before young adults leave the soil and begin the next generation. The entire life cycle from egg to adult may be completed in as little as 3-4 weeks depending on the temperature. Because of their proclivity and relative short gestation period, potted plants can host each stage – egg, larvae, pupae, adult – with multiple generations at once. Because of this, remedies usually require repeated applications until there are no surviving eggs.

Symptoms of the pest

Plant symptoms that indicate fungal gnats are sudden wilting, loss of vigor, poor growth, and yellowing of the leaves. With severe infestations, a considerable portion of the plants may be lost.

How to prevent the pest?

Inspect plants thoroughly prior to purchase for signs of insect pests. Turn up soil carefully near the base of the plant and look for the glossy, clear larvae. Reject any plant sending up flying gnats.
Fungus gnats do best in damp soils; be careful not to overwater, especially during winter months when plants require less water. When potting, avoid organic material that holds water, such as algae, which may encourage egg laying.

Solutions for controlling the pest

If pests are present, allow the soil to dry to a depth of one to two inches between waterings. This not only kills the larvae and inhibits the development of eggs, it also makes the soil less attractive to egg-laying females.
Use yellow sticky traps placed horizontally at the soil surface to capture large numbers of egg laying adults. The gnats are attracted to yellow and can easily be removed from the trap before they can lay more eggs.
Top-dress houseplants with beneficial nematodes to destroy the larval stage. Nematodes are microscopic roundworms that penetrate fungus gnat larvae, as well as harmful lawn and garden grubs, fleas, and other soil-borne pests (they do not harm earthworms), and then release a bacterium that consumes the pest from the inside out. The long-lasting nematodes are safe for use around pets, plants, and your family.

Potting Soil

The structure of potting soil determines how much water and air are available to the roots. Air is important for the roots’ oxygen supply and for the micro-organisms in the root environment.

Roots need oxygen for growth, maintenance of the root system, and the uptake of water and nutrients. The provision of a good supply of air for fast growing plants is of vital importance for obtaining good results. A shortage of air in the early stages of cultivation leads to a poorly developed root system, which hampers growth resulting in a smaller yield.

Air (Oxygen) moves from the air supply outside or in the growing room, through large pores in the medium to the root surface by diffusion. The structure of the potting soil in use is dependent on the quality of the raw materials comprising the soiless potting mix. The best soiless potting media starts with virgin peat that has long-term stable structural characteristics.

Vertically cut or shaved peat?

Two different methods of harvesting can be used to exploit peat deposits: the cheapest but least efficient method consists of “shaving off” the top layer of peat. The disadvantage of this technique is that the structure is less coarse which has an undesirable effect on the air/ water relationship.

The second method consists of cutting the peat vertically. This is the most well known method from times past. The peat blocks that were previously used as fuel for cooking and heating houses were cut in this way. This is an expensive way of extracting peat. When peat is cut into blocks it has to be turned by hand to dry out.

The coarser the peat is, the better will be the balance between the water and air it contains. This ensures the roots develop better in the medium. The plants are healthier and the tendency of the mix to compress is reduced.

High and low peat

One of a potting medium’s main ingredients is peat. This is a century’s old, naturally occurring material formed from old vegetation. Peat originates from regions where climatic circumstances caused new plant material to form faster than the dead vegetation could rot. Slowly but surely this process built up a layers of organic materials that become several meters deep in some locations.

Two different types of peat can be differentiated: high peat and low peat. Low peat is formed in regions where groundwater levels are high and there are plenty of nutrients. Low peat typically contains a high proportion of rotten material and can have high levels of silt; sand and harmful salts which makes it an unsuitable base for a good potting soil. High peat is formed under the influence of rainwater in low nutrient regions and its principal ingredient is sphagnum moss. This is a small plant that dies off from below while continuing to grow above on its own remains. The remains of other plants are also found here; grasses, tree limbs and leaves for example.

Sphagnum moss

Sphagnum moss is particularly suitable for use as a growing substrate because it is natural, light, clean and easy to work with. It has a low nutritional content; a pH that ranges from 3.5 to 4.5 and has good water retention properties (up to 20 times its own weight). The profile of high peat in the flat peat region of Northwest Germany, contains different, distinct layers that formed in different periods.

Calcium (Ca) deficiency guide

Calcium deficiency guide

Calcium occurs throughout the entire plant. It is used for many processes in the plant, however, calcium is most important for the growth process. It has a regulating effect in the cells and contributes to the stability of the plant. Plants have two transportation systems at their disposal: the xylem vessels and the sieve vessels.

Most nutrients can be transported via both systems, however, for calcium this is not possible. Since calcium can be transported almost exclusively via the xylem vessels, it is an element that deposes of little mobility within the plant. It is, therefore, important that a sufficient amount of calcium is always available in the root environment, so that it will be continuously available for absorption by the plant.

About calcium in short

What is it and what does it do?: Calcium is important to the growth process.; Has a regulating effect in the cells and contributes to the stability of the plant.

What can you see?: Yellow/brown spots, surrounded by a sharp brown outlined edge.

What can you do?: Add calcium by applying a liquid lime fertilizer such as a calcium nitrate solution.

Symptoms of a deficiency

The older, larger leaves just above the bottommost ones will show the first symptoms. Yellow/brown spots occur, which are often surrounded by a sharp brown outlined edge. In addition, the growth is curbed and in serious cases the tops are smaller than normal and do not close.

Development of a deficiency

The symptoms often appear quickly; within one or two weeks the first spots being visible on the older leaves. The spots usually start as small, light brown specks that increase in size over time.

After two weeks, the older leaves show ever increasing spots and the spots also often appear at the edge of the leaves, as with a potassium deficiency or with scorch symptoms. The spots have a sharp outline and do not originate exclusively at the edge of the leaves. A lag in development is often already noticeable within a week.
Sometimes the growing points will wrinkle up and around the fruits you will find thin, small leaves that are not spotted.
The older leaves die off slowly and yellowish cloudy spots may appear around the necrotic spots. The older the leaf is, the more serious the symptoms are.
The flowering is also hindered and slowed down. Fruits stay small.

Reasons for a deficiency

Culture on calcium fixing potting mix.
An excessive amount of ammonium, potassium, magnesium and/ or sodium in the root environment. The absorption is curbed mostly by ammonium and least by sodium.
Problems with the evaporation caused by an excessively high EC value or by excessively high or low relative humidity.

Solutions to a deficiency

If the EC value of the substrate or the potting mix is too high, it can be easily rinsed out with pure and if necessary acidified water.
Additional calcium can be applied through the nutrient solution by means of liquid lime fertilizers such as a calcium nitrate solution. With an excessively acidic potting mix, lime milk can be used to increase the pH. Use the appropriate potting mix that is not too acidic. Acid potting mix often contains insufficient amounts of lime. Good potting mix and Coco substrates are already limed.

For your information: Be careful with fertilizers containing chloride.

Magnesium (Ca) deficiency guide

Magnesium deficiency guide

Magnesium is an indispensable element for – amongst others – plants. In plants, it represents a building block for chlorophyll (leaf green), and therefore, it is essential for photosynthesis. At the same time, magnesium plays an important role in the energy transfer. Together with calcium, it is also a component of tap water, influencing water hardness. Inorganic magnesium fertilizers are produced using the same bases that are used to produce potassium fertilizers.

About magnesium in short

What is it and what does it do?: Magnesium is indispensable to plants as it is essential for photosynthesis.; Represents a building block for chlorophyll.

What can you see?: Rusty brown spots.; Cloudy, vague yellow spots between the veins.

What can you do?: Spray with a 2% solution of Epsom salts every 4-5 days during about a week.

Symptoms of a deficiency

When there is a shortage, the leaf green in the medium-old leaves under the flowering top will be broken up, and the magnesium will be transported into the young parts of the plant. This breakdown is visible as rusty brown spots and/ or vague, cloudy, yellow spots between the veins. A slight shortage of magnesium hardly affects flowering, although the development of the flowers make the deficiency symptoms worse.

Development of a deficiency

Signs of a deficiency first appear around the 4th-6th week. Small, rusty brown spots and/or cloudy yellow flecks appear in the middle-aged leaves (under the top of the plant).
The color of the young leaves and the fruit development are not affected.
The size and number of rust-brown spots on the leaves increase.
The symptoms spread out over the whole plant, which looks ill. When the shortage becomes acute, the younger leaves are also affected and the flower production will be reduced.

Reasons for a deficiency

The magnesium deficiency can occur because uptake is inhibited because of:

A very wet, cold and/or acidic root environment.
A high quantity of potassium, ammonia and/or calcium (for instance high concentrations of calcium carbonate in drinking water, or clay potting mixes rich in calcium) in comparison with the quantity of magnesium.
A limited root system and heavy plant demands.
A high EC in the growing medium, which hinders evaporation.

Solutions to resolve a deficiency

When a shortage is diagnosed, the best thing to do is to spray with a 2% solution of Epsom salts.
Fertilization via the roots: Inorganic: Epsom salts on hydroponics or Kieserite (magnesium sulphate mono hydrate). Organic: composted turkey or cow manure.

Recovery

Rectify the possible causes: In potting mixes, when the pH is too low (less than 5), use magnesium containing calcium fertilizers. In hydro, temporarily apply a nutrient solution with a higher pH (6.5). When the EC is too high, rinse and/or temporarily feed with drinking water only.

When growing indoors, keep the root temperature between 20 – 25 degrees Celsius. A little extra magnesium is not particularly harmful. When growing in potting mixes, excessive quantities of magnesium do not appear quickly. Too much magnesium inhibits the uptake of calcium, and the plant displays general symptoms of an excess of salts; stunted growth, and dark-colored vegetation.

Iron deficiency guide

Iron is a vital element for plant life. Iron has a number of important functions in the overall metabolism of the plant and is essential for the synthesis of chlorophyll. In general, iron is poorly absorbed by the plant. It can only be sufficiently taken up by the roots in certain forms and under proper conditions.

Potting mixes seldom contain too little iron, but it is possible that forms of iron that can be absorbed by the plant are lacking. The absorbency of iron is strongly dependent on the pH. Usually, there is sufficient iron present in absorbable form in acidic potting mixes.

About iron in short

What is it and what does it do?: Iron has a number of important functions in the plant’s overall metabolism and is essential for the synthesis of chlorophyll.

What can you see?: Strong yellowing of especially the young leaves and growth shoots between the veins.

What can you do?: The best thing is to spray the plants with a watery solution of EDDHA or EDTA chelates.

Symptoms of a deficiency

Iron deficiency can occur during periods of heavy growth or high plant stress and is characterized by a strong yellowing of the young leaves and the growth shoots between the veins. This occurs chiefly because iron is not mobile in the plant. The young leaves can’t draw any iron from the older leaves. With a serious iron shortage, the older leaves and the smaller veins in the leaf can also turn yellow.

Development of a deficiency

Green/yellow chlorosis, from inside to the outside in the younger leaves and in the growth shoots. The veins remain mostly green.
Continued yellowing of the leaves to sometimes almost white. Also, large leaves turn yellow. This inhibits growth.
In serious cases the leaves show necrosis, and the plant’s growth and flowering are inhibited.

Reasons for a deficiency

The pH in the root environment is too high (pH> 6,5).
The root environment contains a lot of zinc and/or manganese.
The concentration of iron is too low in the root environment.
The root temperature is low.
The root medium is too wet, causing the oxygen supply in the roots to stagnate.
The root system functions inefficiently due to damaged, infected or dead roots.
There is too much light on the nutrition tank; light promotes the growth of algae. Algae also use up the iron and break down iron chelates.

Solutions for a deficiency

Lower the pH.
Iron chelates can be added to the substrate.
Drainage can be improved, or the ground temperature can be increased.
A leaf nutrient with iron chelates can possibly be applied. If a good fertilizer is used with hydroponic growing, an iron deficiency is almost out of the question.
The best thing you can do is to spray the plants with a watery solution of EDDHA (max. 0.4 grams per gallon) or EDTA chelates (max. 2 grams per gallon).

Potassium deficiency guide

It is necessary for all activities having to do with water transport and the opening and closing of the stomata.

Potassium takes care of the strength and the quality of the plant and controls countless other processes such as the carbohydrate system.

About potassium in short

What is it and what does it do?: Potassium takes care of the strength and the quality of the plant.; Controls countless other processes such as the carbohydrate system.

What can you see?: Dead edges on the leaves.

What can you do?: In case the EC in the substrate or potting mix is high, you can rinse it with clean water.; Add potassium yourself.

Symptoms of a deficiency

Evaporation is reduced if there is a shortage of potassium. A consequence is that the temperature in the leaves will increase and the cells will burn. This occurs mostly on the edges of the leaves, where normally, evaporation is highest.

Development of a deficiency

Tips of the younger leaves show gray edges.
Leaves turn yellow from the edge in the direction of the veins and rusty colored dead spots appear in the leaves.
The tips of the leaves curl up radically and whole sections of the leaves begin to rot. The leaves keep on curling and ultimately fall off.
An extreme shortage produces meagre, unhealthy-looking plants with strongly reduced flowering.

Reasons for a deficiency

Too little, or the wrong type of fertilizer.
Growing in potassium-fixed potting mixes.
An excess of sodium (kitchen salt) in the root environment, as sodium slows down potassium intake.

Solutions for a deficiency

In case the EC in the substrate or potting mix is high, you can rinse with water.
Add potassium yourself, either in inorganic form: Dissolve 5 – 10 grams of potassium nitrate in 2.5 gallons of water. In acidic potting mixes, you can add potassium bicarbonate or potassium hydroxide (5ml in 2.5 gallons of water).
Add potassium in organic form: Add a water solution of wood ash, chicken manure or slurry of manure (be careful not to burn the roots). Extracts of the grape family also contain a lot of potassium.

For your information

Potassium is absorbed quickly and easily by the plant. In a hydroponic system results get visible within several days. Potassium supplementation by leaf fertilization is not recommended.
Too much potassium will cause salt damage, calcium and magnesium deficiencies and acidification of the root environment!

Manganese deficiency guide

Manganese is an essential trace element for all plants. Manganese acts as an activator for different enzyme reactions in the plant, for example in water-splitting during photosynthesis, the synthesis of amino acids and proteins and the build up of plant cell membranes and chloroplasts.

Manganese is generally taken up via the roots. Once inside the plant it is difficult to transport but not as difficult as calcium or iron for example. Silicon and molybdenum improve the transport possibilities for manganese in the plant.

About manganese in short

What is it and what does it do?: The metal manganese is an essential trace nutrient and acts as an activator for different enzyme reactions in the plant.

What can you see?: Yellow stripes appear between the leaf’s side veins.

What can you do?: Using products that contain trace elements (Tracemix).

Manganese deficiency guide

Symptoms of a deficiency

A manganese deficiency causes different physiological changes in the plant due to a decrease in protein production. Among others, this causes less nitrate to be fixed in the plant, which can lead to dangerously high levels of nitrate. Additionally, a lot of chemical reactions in plant cells slow down which may result in a build up of organic acids.

Development of a deficiency

The progression in chronological order:

Yellow stripes appear between the leaf’s side veins on the larger leaves at the top of the plant.
The yellowing between the side veins spreads further over the leaf and small, yellow/brown necrotic spots can form.
The final result is a small plant (-10%) with minimum fruit/flower production.

Manganese deficiency guide

Reasons for a deficiency

In practice, the most common reason is that the pH in the substrate is too high. Like iron, manganese is easily dissolved at a low pH value in the substrate. If the pH is too low, a risk of excess manganese may occur. At high pH values manganese precipitates into manganese oxide (MnO2) which cannot be taken up by the plant which can cause deficiency.

Solutions to resolve a deficiency

Check the medium’s pH when the first symptoms are noticed. High pH values mean that there is less manganese available for the plant. By lowering the pH of the nutrition (pH minus (down)) the medium’s pH can be lowered to 5.0 – 5.5.
Low substrate temperature can be the cause of reduced manganese absorption. If a deficiency is noticed, check that the substrate temperature is sufficiently high (68 – 77 oC) during the day.
Using products that contain trace elements may also help. A manganese deficiency is usually not a problem on its own. To facilitate manganese transportation in the plant, molybdenum is needed. Thus, the problem may well be a molybdenum deficiency. High levels of phosphorus may also result in a reduced availability of trace elements like zinc, copper and (of course) manganese. CANNA advises to use a mix of all needed trace elements. Trace elements can be given to the plant both in the feeding and by spraying the leaves. Spray the plant at the end of the day and spray daily with water after spraying to prevent burning.

Excess Manganese!

When there are high concentrations, manganese precipitates into manganese oxide (MnO2 or black manganese) which causes yellow-brown spots on the leaves. Initially, small spots will appear along the main and side veins of the leaf, following this, the spots will spread out from the veins. Excess manganese can be a result of a low pH in the substrate.