Category: Cultivation advice
Date published: April 06, 2020

A good fruit set is the start of a good production!


Spring is here! And time for fruit crops to flower. A strong fruit set is all important for a high quality and healthy yield.

The flower buds, formed in fall, are swelling and ready to open. During the short flowering period the crop experiences a tremendous hormonal shift moving from the earlier vegetative stage to this all-important reproductive phase. In addition to standard nutrition, the crop will require higher concentrations of trace minerals and calcium. Flower buds, embryo and subsequent blossom require zinc, manganese, boron and other trace elements in quantities 80 to 100 times higher than leaf tissue! It is essential that these elements are available and utilized at this stage, as they play an important role during flowering and fruit set. Boron, for example is actively involved in pollen germination and seed, fruit and nut development.

When the flowers are opening, active pollination is needed. Most fruits get the best pollination when the flowers are freshly opening and cross pollinated. So, make sure that there are sufficient pollinators in the crop. When Natupol bumblebees are introduced as planned, good pollination is ensured. This is in addition to natural occurring pollinators, and/or honey-bees that may or may not be in sufficient numbers to support this flower flush.

After pollination, when the pollen is brought to the stigma, the pollen tubes start to grow down the pistil and reach the ovule where fertilization then occurs. After fertilization there is a period of rapid cell division when there is a high demand for energy. Calcium is essential during this period, and often a limiting factor, in order to develop strong cell walls.

What can you do as a grower to ensure good pollination and fruit set?

Make sure that the plants get enough water during flowering and fruit set. Water stress reduces pollen viability, leading to poor fruit set. Avoid over-watering or ‘wet feet’ through proactive irrigation management.

Make sure that there are enough trace elements (such as manganese, boron and zinc) available during flowering. Be ahead of any ‘hidden hungers’ (e.g. leaf sap analysis), and apply appropriate trace element and calcium foliar sprays to correct before they become an issue. Apply a foliar spray of Vidi Terrum + Veni Calcium just prior to flowering, during flowering, and directly after fruit set. Aim for (at least) 3 foliar applications. Vidi Terrum contains a special mix of amino acids and seaweed extracts which supports the fruit set of the plant. Veni Calcium supplies the plant with readily available calcium that is needed for the cell wall formation during the cell division phase. Veni Calcium also contains boron, which enhances the calcium uptake and plays a vital role in promoting fruit set. Introduce Natupol bumblebees in the crop as soon as the first flowers open.

For further information please do not hesitate to contact Koppert.