Recognizing and Addressing Plant Deficiencies
We often assume our plants are sick when we notice signs of plant deficiencies, such as discolored, wilting leaves, mottled crops, or stunted, weak stems. Growers commonly suspect pests or diseases as the cause. In such cases, however, reaching for the sprayer is a mistake. More often than not, the issue stems from a nutrient deficiency. Pesticides won’t solve this problem, and unnecessary spraying only releases chemicals into the environment.
What is missing and when?
Early summer is the time when the plants already growing outside have used up most of the nutrients that can be taken up from the soil and released with planting. Many of the early spring-sown crops are already in the seed and fruit maturation stage, when they are particularly in need of nutrients. And summer crops such as tomatoes, peppers, cucumbers, cabbages that have been planted or sown in situ are developing and strengthening their green parts, stems and leaves, preparing for flowering and setting.
It is essential to replenish the reduced nutrient supply during the growing season, as plants can quickly start to show signs of nutrient deficiency. The most typical time for deficiency symptoms to appear is between flowering and harvest.
Symptoms
Some symptoms of deficiency diseases are easily confused with those of fungal, bacterial diseases or pests. In general, poor or distorted growth, discolouration, distorted leaf or fruit shape are common. Deficiency diseases can also be indicated by reduced or absent flowering, flower drop, or poor flower attachment. Prevention is the best solution, but once the problem is established it is important to know and recognise the deficiency symptoms. If we replenish nutrients and micronutrients, plants will recover quickly.
The German baron and the grain
Justus von Liebig, a German scientist, chemist and founder of agricultural chemistry, was one of the first to study the elemental nutrient requirements and uptake of plants, distinguishing between macro, meso and micro elements that are essential for the healthy development of plant organisms. He also described the phenomena that occur in plant organisms when certain elements are deficient.
His results have been widely praised or criticised, but it was his work that laid the foundations for nutrient replenishment. And Liebing’s law of minimums, which he discovered, states that plants can use the nutrients present in the smallest proportion to the other nutrients present. In practice, this means that even if there is enough nitrogen available, if there is a shortage of phosphorus or potassium in the soil, for example, plants will develop deficiencies and will not grow healthily. Of course, this also means that if they only receive one type of nutrient, and thus become unilaterally enriched in one nutrient, they will not have access to other equally important elements.
Micro-macro
In a very disaggregated way, plants need 17 types of nutrients. To further colour the picture, they are needed in different proportions, at different times and in different quantities. Some plants need nitrogen, others need potassium, and some species need different nutrients at different stages of their life.
Nutrients are divided into macro, meso and micro elements:
- Macronutrients are Nitrogen (N), Phosphorus (P), Potassium (K), Carbon (C), Oxygen (O) and Hydrogen (H).
- Secondary nutrients are Calcium (Ca), Magnesium (Mg), and Sulphur (S).
- Micronutrients or trace elements are Iron (Fe), Zinc (Zn), Manganese (Mn), Boron (B), Copper (Cu), Chlorine (Cl), Molybdenum (Mo), and Nickel (Ni).
Various deficiency diseases
Each deficiency causes a different set of symptoms in different plants. It is worth examining each anomaly closely to see whether it may be caused by a deficiency of one or more nutrients.
Nitrogen deficiency
Nitrogen is mainly needed for the healthy development of the root system and the green parts, the so-called vegetative organs such as stems and leaves. In its absence, the plant shows stunted growth, leaves turn yellow and stiff. The whole plant has a yellowish, light greenish appearance. Deficiency always appears first on the older, lower leaves.
Leaf plates fade uniformly, then turn yellow. There is no difference in the colour of the area between the leaf veins, leaf margins and veins within the leaves. The stunted, weak root system also makes it difficult to absorb nutrients. Nitrogen is needed by all our crops.
Phosphorus deficiency
Phosphorus plays an extremely important role in photosynthesis, root formation, respiration and basic biological processes. Phosphorus is found in the reserve nutrients in seed crops, is crucial for crop formation and affects the quantity and quality of the crop. In its absence, leaves become stiffly erect and take on a reddish-purple colour. Plant growth slows down, stems remain thin, flowering starts later and leaves are smaller and less abundant than normal. The crops most in need of fertilization are onions, lettuce and maize.
Potassium deficiency
There are many plants that require higher amounts of potassium, such as green beans, tomatoes and carrots. An optimal supply of potassium increases the tolerance of plants, the formation of pigments, and increases the sugar, protein and vitamin content of the crop.
A crop with a favourable potassium supply stays fresh longer and is more resistant to external influences. In case of deficiency, symptoms appear later, especially on older leaves. It is characterised by yellowish discoloration starting at the leaf margins or the leaf apex in the vascular spaces, followed by brownish dieback towards the edge of the leaf plate.
Calcium deficiency
With a lack of calcium, the leaves of plants become distorted, small and deformed. Calcium is a constituent of the plant cell wall, and an optimal calcium supply is responsible for the structure of the fruit, which, if lacking, develops brownish, softened flesh.
The most striking symptom on leaves is brownish dry necrosis in the vascular spaces, brown spots starting from the leaf margins or leaf tip and later coalescing on the whole leaf blade. Younger leaves are spooned towards the backbone. The breeding apex dies back, becoming papery dry in dry weather and slimy rotten in rainy weather.
Magnesium deficiency
In horticultural production, magnesium application is particularly important. Horticultural crops require proportionally much higher amounts of magnesium than arable crops and it is mainly incorporated in the leaves, which are not recycled as in arable crops.
The deficiency symptom appears mainly on the leaves and is characterised by yellow discolouration running from the leaf edge or tip towards the leaf veins. The discolouration is never pale or dirty yellow, always bright yellow.
Sulphur deficiency
Sulphur is the sixth most important nutrient for plants. The decline in organic fertilisation is the main reason why soils have become sulphur deficient. Nitrogen and phosphorus, which are leached during fertilisation, make it even more difficult for plants to absorb sulphur. Some crops are particularly sensitive to sulphur, including cruciferous vegetables and onions, and arable crops such as lucerne, brassica and tobacco. Sulphur-deficient crops are very similar to nitrogen-deficient crops.
The leaves of the plant turn yellow, and the whole plant takes on a yellowish tinge, but in the case of sulphur, yellowing always starts on the younger leaves. Sulphur-deficient plants are shorter than normal and, if the deficiency reaches an early stage of development, will grow stunted.
Iron deficiency
Of the micronutrients, iron deficiency produces the most pronounced symptoms and is the most difficult to correct. Minor deficiencies cause the youngest leaves of the plant to turn yellowish green. As the deficiency increases, the interveinal fields turn yellow or orange-yellow. It occurs on the youngest leaves, first with yellowish-white streaks, then almost the whole leaf turns yellowish-white or completely white.
Zinc deficiency
Zinc, like boron, is an important micronutrient, mainly responsible for the fertilizing ability of pollen and successful fruit setting. Crops with a high zinc requirement include maize, beans, soya, hops, flax, grapes, medicinal plants such as castor beans and most citrus fruits.
In case of deficiency, the symptoms are relatively difficult to identify precisely, but in general, leaf deformities, small leaflets and discoloured spots in the leaf veins are characteristic of zinc-deficient plants.
Boron deficiency
Boron is necessary for the development of healthy pollen and for the viability of pollen, next to zinc. It plays an essential role in the uptake of other nutrients, regulates the differentiation of meristematic cells and promotes their elongation. It plays an important role in the formation of the fine structure of cell walls. Its deficiency is often the cause of poor fertility and failure to produce crops.
A boron-deficient plant uses water less efficiently and has more difficulty withstanding drought. Boron deficiency can be a symptom of discoloration or dieback on the youngest leaves and inhibited root formation. Boron-deficient plants will wilt more quickly and show symptoms of water deficiency earlier than healthy plants.
Prevention and treatment of deficiency symptoms with Biomit technology
Plant deficiency symptoms should be prevented rather than treated. A deficiency symptom that has already developed can greatly set back the development of the crop, and treatment always requires more work and effort than if the plants were to be included in a complex technology.
And the best way to prevent this is to create an environment for the plants before planting where nutrients are harmoniously available. In this way, the various nutrients will always be present in the right quantity and quality, in an absorbable form.
Humic acid
The recommended technology is to apply Biomit Genesis high concentrations of humic acid before sowing or planting, or at the latest at the same time. Humic acid, i.e. potassium humate, is a water-soluble plant and soil conditioner that can establish a healthy soil composition over the long term, improve soil structure and is readily taken up by plants. It is made from a special carbon compound called leonardite.
Humic acid alone can improve the condition of plants, causing increased photosynthesis and an increase in green colour bodies. It also has an important chelating effect. This means that it can activate microelements that are immobilised in the soil and make them available for uptake by plants. Humic acid treatment improves soil structure and nutrient enrichment. Crops develop stronger roots and become more resistant.
Earthworm humus
Besides humic acid, the other main tool for soil conditioning is worm humus. The various annelids, such as earthworms, earthworms, dung worms and forest worms, produce humic substances during their metabolism that are both structurally, chemically and microbiologically excellent for feeding crops. The worms’ intestinal tracts are enriched with enzymes and microbes that contribute to the development of a rich soil life. Worm castings provide the perfect medium for beneficial bacteria and fungi to enter into symbiotic relationships with the root system of the plants.
Biomit Terra soil conditioner contains a high concentration of worm humus in dissolved form. This is an advantage for two reasons, the aqueous suspension allows both the plants and the bacteria in the soil to easily access the nutrients and enzymes found in the worm humus. The soil improvement effect is therefore faster and longer lasting.
Be sure to use these two technologies before sowing or planting, or in combination. This greatly reduces both the risk of deficiency symptoms and the risk of bacterial and fungal diseases.
The treatment
Once a problem has occurred, i.e. a shortage has developed, the stock should be treated as soon as possible. It takes a long time to recover from deficiencies and the plant is slow to incorporate the elements it has been given. It is advisable to use foliar fertiliser for treatment. Foliar fertilisers are absorbed through the cell walls of the leaves and green parts of the plant and can provide the plant with the nutrients it needs in a short time.
Biomit plant vonditioner is an excellent solution for replenishing micro and meso elements and thereby treating deficiency symptoms. By using it, you can effectively replenish the elements copper, zinc, iron, boron and manganese in the plant population within a short period of time. In addition, its micro-dolomite content helps to ensure perfect adherence and the formation of a proper coating on the leaves of the plants.
Dolomite also provides protection against chewing pests (e.g. leaf beetles, owl beetles). This is a great advantage, as the pests will first appear on the already weakened nutrient deficient plants.
