How To Fix A Manganese Deficiency In Plants
Plants require nine essential nutrients for growth including manganese. Plants do not need much manganese for health or growth, but this micronutrient is essential. Manganese is extremely important for photosynthesis. The only nutrient more essential for plants than manganese is iron. When there is manganese toxicity or deficiency, the growth of plant tissue is often severely impacted.
Plants require manganese for a variety of biological systems including nitrogen assimilation, respiration and photosynthesis. Manganese is just as important for the growth of pollen tubes, pollen germination, resisting root pathogens and the elongation of root cells. A manganese deficiency in plants often results from soils too rich in organic matter or with high pH levels.
Manganese is critical for synthesizing fatty acids, the regulation of the carbohydrate metabolism and the energy budget. An adequate supply of manganese is required to decrease nitrates within the plants. Manganese also enhances the growth of the secondary roots and elongates cells to increase plant growth.
How does a Manganese Deficiency Affect the Quality of Your Plant?
A manganese deficiency in plants often results in chlorotic spots around the veins in mid and new leaves due to the negative impact of chloroplast development. Manganese is critical for the process of photosynthesis or the conversion of sunlight into energy for the plant. Since manganese is unable to move throughout the plant, the symptoms of a deficiency can be seen in new growth.
The quality of the plant is impacted due to negative chlorophyll production resulting in an unnatural coloration of the leaves. New leaves turn olive green as opposed to a naturally bright green coloration. The chlorosis present around the veins results in abnormally dark veins.
What are the Symptoms of a Manganese Deficiency?
The most common manganese deficiency symptoms include:
- Plants turn a pale green
- Decreased growth
- Older and new leaves are affected
- Paleness between leaf veins
- Leaves turn brown then die
- Mottled yellowing in cabbage leaves
- Curled edges on beetroot leaves
- Yellow stripes on corn and onion leaves
- Yellowing at the base of cannabis leaves
- Mottled brown spots
The most common symptoms are decreased growth and pale greens leaves. In many plants, the symptoms are first seen on either the oldest or newest leaves. Although the areas surrounding the veins remain a normal color, the areas in between turn a pale green. As time passes, these areas become even paler, the veins enlarge, and the leaves often turn brown and die.
The leaves on cabbage plants often become mottled and yellow due to interveinal chlorosis. Beetroot leaves become spear-shaped or triangular with curled edges, small dead patches, yellow mottling and a speckled appearance. These distinctive and common symptoms are referred to as speckled yellow. Yellow stripes appear on sweetcorn and onion leaves due to interveinal chlorosis.
The veins on tomato plant leaves stay green, but the areas located between the veins become yellow. As the manganese deficiency worsens, the yellow coloration intensifies causing a pattern like a net appearing on the leaves.
Possible Confusion with Other Symptoms
- The symptoms for manganese and iron deficiencies are similar, leading to confusion
- A magnesium deficiency also causes a yellow coloration to appear around the veins
- A calcium deficiency results in similar brown spots on the leaves
- Brown spots are also caused by fluctuations in pH
What Causes a Manganese Deficiency in plants?
A deficiency can be caused by:
- Calcareous, neutral or well-drained soil
- Heavy lime applications
- Sands with limestone
- Swamps with an alkaline marl base
- Excessive pH levels
- Too much iron
A manganese deficiency in plants is most common on calcareous, neutral or well-drained soil. Heavy use of fertilizer or lime can also result in a deficiency. A magnesium deficiency is also common in swamps with an alkaline marl base or sands with limestone. A deficiency frequently results when plants receive too much iron, or if the pH is excessively high.
The leaves of the plant will be deficient in manganese if there is less than 20mg available, with severe symptoms resulting from levels below 10mg. Healthy plants generally have between 50 and 200 mg of manganese.
How to Fix a Manganese Deficiency in Plants
For effective root absorption of manganese, the pH range should be between 6.0 and 7.0. For cannabis plants, the level should be decreased to 6.0 to 6.5. Plants grown using hydroponics will thrive with a range between 5.5 and 6.5, but for the best absorption the level should remain under 6.0. To treat a manganese deficiency in plants, the system needs to be flushed with nutrients, pH water and manganese.
Once any excess nutrient salts and iron are removed from the system, the roots can effectively absorb the manganese due to the restoration of correct pH levels. Manganese sulphate is effective for the management of a manganese deficiency. If there is limestone in the sand, the swamps are marl-based and alkaline, or heavy lime has been used, manganese sulphate is recommended.
- Make any necessary pH adjustments for plant root absorption of manganese
- Flush the system with nutrients, pH water and manganese
- Use manganese sulphate
How Long Does It Take for a Plant to Recover from a Manganese Deficiency?
Once you have finished treating your plants for a manganese deficiency, there should not be any yellowing leaves or brown spots spreading to the other leaves within about seven days. Once a leaf has been affected by a manganese deficiency, it will most likely not turn green or recover. Pay close attention to the plants to make certain they are recovering properly.