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Crops

Fruits

KALI Academy

Consumers expect fresh, healthy-looking fruit, which should be sufficiently developed and ripened when it is offered for sale. For every fruit grower, this poses the annual challenge of producing quality fruit that can stand up to the critical gaze of buyers. The balanced supply of minerals to the plants can make a major contribution to harvesting "extra class" fruit. 

At a glance

It's all about taste and preservation for fruit

Besides the "external" quality characteristics of fruit, the "internal" factors, such as mineral and vitamin contents, as well as the fruit's content of stress-reducing ingredients, e.g. anthocyanins, are among the value-adding properties. Both of these categories can be significantly improved through optimized plant nutrition.

  • Potassium ensures efficient plants, better frost resistance.
  • Magnesium guarantees high internal and external quality.
  • Sulfur is indispensable for the production of plants' own defense substances.
  • Micronutrients control important stages of plant development.
Importance and benefit

Produce best qualities

In today's fruit growing, the focus is on producing high-quality fruit. The highest quality fruit can only be produced if the fruit trees are supplied with sufficient mineral nutrients. The nutrient removal by the fruit is relatively low compared to agricultural crops, but when measuring fertilization, it must be taken into account that nutrients accumulate predominantly in other plant parts such as wood and the leaves.

Fertilization recommendations in fruit growing are based on the needs of the fruit trees and not on the pure withdrawals by the harvested product.

Fruit

K2O

(kg ha-1)

MgO

(kg ha-1)

Pome fruit (apples, pears etc.) 90-120 20-30
Stone fruit 100-140 30-40
Strawberries 80-150 20-30
Soft fruits 60-80 15-25
Nutrients

The most important nutrients for fruits

Potassium – for powerful trees and bushes

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  • Potassium is involved in many metabolic processes crucial to the yield and quality of fruit
  • Potassium improves water utilization, assimilation performance as well as fruit set and therefore has a positive effect on the yield.
  • Quality criteria such as fruit acidity or skin coloration are also positively influenced by potassium
Market value
exterior quality markers
Health value
interior quality markers
Size/weight Sugar content/acid content
Colour Mineral nutrients
Shape Vitamins
Taste Dietary fibre
Unblemished by pests and diseases Bioactive ingredients (e.g. polyphenols)

Magnesium guarantees high quality

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For a very good quality of the harvested products, it is necessary to ensure the supply of magnesium to the trees and bushes. 

  • Magnesium not only promotes assimilation, but also plays an important role in assimilate transportation.
  • This increases the sugar and acid content of the fruit.
  • The formation of aroma substances, as well as the size and coloration of the fruit, is improved.
  • Magnesium deficiency is quite common in fruit crops and can be aggravated by high levels of calcium or potassium in the soil.

As observed in a two-year apple trial, the magnesium and chlorophyll content was significantly increased by treatment with EPSO Microtop. The increase of the Mg content in the fruits led to a better coloration of the fruits.

Sulfur – indispensable for health

  • Sulfur activates important enzymes in energy and fatty acid metabolism. It is essential for the synthesis of sulfur-containing amino acids, influences overall protein synthesis and thus has a positive effect on yield.
  • Sulfur is irreplaceable in the production of the plant's own defense substances, the so-called phytoalexins.
    Great importance is now attached to certain sulfur-containing compounds, such as glutathione, which play a central role in the plant's resistance to diseases and pests.
    Sulfur enables the plant to maintain its physiological processes optimally even under drought stress and to avoid or at least minimize yield losses. Sulfur is a component of the metabolic product glutathione, which, as an antioxidant, renders oxygen radicals produced during drought stress harmless and therefore prevents necrosis of the leaves.
  • According to recent findings, sulfur-containing compounds are also involved in stress defense against ozone and heat damage.
  • Optimized sulfur supply leads to efficient nitrogen utilization. When there is a lack of sulfur, the nitrogen taken up cannot be converted into proteins, and a signal is sent to the roots to take up less nitrogen. Therefore, the plant's need for sulfur must be met in order to make optimal use of nitrogen. 

Don't forget about micronutrients

Micronutrients such as boron, zinc, and manganese are becoming increasingly important in modern fruit growing. In many soils, they are either deficient or cannot be absorbed sufficiently by the woody plants.

Since micronutrients control important stages of plant development, yield and quality losses can result – even from temporary deficiencies.

  • Boron is of great importance for the fertilization of flowers, among other things. Deficiencies result in lower fruit set and malformed fruits.
  • Zinc controls numerous enzyme reactions. Insufficient zinc supply results in stunted shoots and leaf discoloration.
  • Manganese deficiency increases e.g. apple speckling. Furthermore, the storability of the fruit is greatly reduced.

Micronutrient deficiencies can be remedied effectively and quickly by using foliar fertilizers.

Fertilizer recommendation

Fertilizer recommendations for fruits

All types of fruit are very sensitive to chloride or salt. Therefore, potassium and magnesium in sulfate form are used in fertilization for avoiding risks to yield and quality.

Recommendation for soil fertilization

Depending on crop type

  • approx. 200–500 kg/ha Patentkali®, depending on crop type
  • approx. 100–200 kg/ha ESTA® Kieserit  

Product recommendation

Recommendation for foliar fertilization

Foliar fertilization effectively supplies the plant with the micronutrients boron, manganese, or zinc.  

It also supplements soil fertilization with rapidly available macronutrients such as magnesium or sulfur. In phases of strong growth, fertilization through the leaf covers peaks in demand and reliably ensures an optimum supply of nutrients even in dry conditions or when sulfur mineralization is too slow.

This ensures the best yields and qualities. If deficiency symptoms have already occurred, foliar fertilization provides an effective and quickest possible remedy. 

Product Recommendations

EPSO Top as 2-5 % solution, 25-50 kg/ha (divided into 2 to 3 sprays of  15 kg/ha; application possible together with crop protection products), timing: before flowering to fruiting or when deficiency symptoms appear. All EPSO products are suitable for fertigation. 

Deficiency Symptoms

Deficiency Symptoms ABC

Open Deficiency Symptom ABC