High Quality Fruit
Producing top quality harvests
Modern pome fruit production is driven largely by the need to produce fruit of the highest quality. Only fruit trees supplied with sufficient minerals are able to produce premium fruit. Even though nutrient removal in fruit production is relatively low in comparison to agricultural crops, fertiliser calculation needs to take into consideration the fact that nutrient accumulation in other plant components, such as wood and leaves, is relatively high.
Fertiliser recommendations in pomiculture are therefore determined by the fruit trees’ total requirements, not simply by calculating the nutrient removal by the final harvested product.
For pome fruits, the following nutritional requirements can be taken as a general guide (assuming a moderate level of soil fertility)
|Pome fruit (apples, pears etc.)||
Fertilisation influences health benefits and market value of fruits
The cultivation of high quality fruit needs to meet a range of standards in order to be rewarding and profitable. In addition to `exterior´ quality factors, there is an increasing number of `interior´ factors to be considered, such as the fruit’s mineral and vitamin contents, as well as the fruit’s proportion of “anti-stress” components, such as anthocyanins (plant pigments).
exterior quality markers
interior quality markers
|Size/weight||Sugar content/acid content|
|Unblemished by pests and diseases||Bioactive ingredients (e.g. polyphenols)|
Potassium for highly productive trees and bushes
- Potassium is involved in many of the plant’s metabolic processes, all of which contribute to the potential yield and quality of the fruit it produces.
- Potassium increases the plants’ water use efficiency and assimilation of reserves and therefore positively contributes to successful fruit formation and a profitable harvest.
- Potassium positively influences quality criteria such as fruit acidity and skin pigmentation.
Magnesium guarantees high quality
In order to ensure premium quality harvests, the magnesium requirement of trees and bushes must be adequately supplied.
- Magnesium not only promotes assimilation, but also plays an important role in assimilate transport. This increases both the sugar and acid content of fruit.
- Magnesium improves the content of natural aromatic flavour compounds, as well as fruit size and pigmentation.
- Magnesium deficiency is a common occurrence in fruit orchards, and may be excaserbated by excessive soil levels of other cations such as calcium or potassium.
A two year trial with apples proved that treatment with EPSO Microtop decisively improved magnesium and chlorophyll proportions. The increased Mg content of the fruits resulted in an improvement in the fruit pigmentation.
Sulphur – indispensable for health
Sulphur plays a central role in the plants metabolism:
- Sulphur is an essential factor in the development of amino acids, and therefore proteins, and is indispensable for the production of plant-produced defence substances, so-called phytoalexines.
- Today, great importance is given to certain sulphur-containing compounds such as glutathione, which is essential for the plants’ resistance against diseases and pests.
- Recent research has shown that sulphur-containing compounds are also involved in decreasing stress susceptibility due to ozone and heat damage.
Don’t forget micronutrients
In modern pomiculture, micronutrients such as boron, zinc and manganese are becoming increasingly important. Many soils either lack these nutrients, or otherwise the plants are not able to absorb sufficient quantities. As these micronutrients control particular plant development stages, even a temporary deficiency may lead to significant losses of quality and crop yields.
- Boron is important for pollination of the flowers. Deficiency may lead to diminished fructification and malformed fruit.
- Zinc controls a number of enzyme reactions. Insufficient supply may cause stunted shoot growth and leaf discolouration.
- Manganese deficiency increases the occurrence of bitter pits in apples, and decreases storability.
Micronutrient deficiency may be rectified efficiently and quickly by applying foliar fertilisers.
All types of fruit are very sensitive to chloride i.e. salt. This is why potassium and magnesium fertilisation is applied in sul-phate form, in order to minimise risks for yield and quality.
Recommendations for soil conditioning
approx. 200–500 kg ha-1Patentkali®, depending on crop type
approx. 100–200 kg ha-1 ESTA® Kieserit
Recommendations for foliar fertilisation
* EPSO Top, EPSO Microtop and EPSO Combitop as 2-5% w/v solution, at a total rate of 25-50 kg ha-1 (divided into 2-3 treatments of 15 kg ha-1; combined application together with pesticides possible).Time: before flowering, until fruit formation, or whenever symp-toms of deficiency are noticeable. All EPSO-products are also suitable for fertigation.