September 2021

Finding a sustainable solution

There are various ways of protecting early buds and blossoms from unexpected onsets of frost in the spring. One way is to spray them with water or natural oils. This creates an isolating layer that will protect the blossoms from being damaged by frost.

Another option is to spray with protective substances or biostimulants that will increase the plants’ resilience against frost during their growth. However, spraying requires vast amounts of water, and chemical substances do not necessarily constitute sustainable solutions – particularly not when it comes to ecological fruit farming.

Another option is therefore to look at the varieties of fruit that blossom later in the spring, says associate professor Majken Pagter from the Department of Chemistry and Bioscience at Aalborg University. She works on finding solutions to injuries associated with springtime frost during blooming in fruit trees and berries.

- There is a huge difference between when i.e., different varieties of apples or cherries start their blossoming. Obviously, those that bloom later in the spring are better protected against frost damage. The drawback is that these varieties are not necessarily the ones favoured by the farmers. This depends just as much on taste, yield, and many other factors, she explains.

An ancient technique with future potential

A solution to the problem can be to take a closer look at a technique that has been known for thousands of years namely to graft boughs from one type of tree onto the stem of another type of fruit tree. 

This is typically done to harvest fruits from trees of limited height or trees that have a high resilience against diseases or funghi. But according to Majken Pagter, the grafting technique could potentially help fruit trees become more resistant against springtime frost.