A new, natural pesticide against late blight in potatoes

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Anders Lambæk

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Et nyt, naturligt sprøjtemiddel mod kartoffelskimmel

A new, natural pesticide against late blight in potatoes

Denmark In Danish

Project period: May 2026 - November 2026
Supported by: Food & Bio Cluster Denmark

Many of the chemical pesticides traditionally used by farmers to combat late blight in potatoes are currently being banned. As a result, the Danish potato industry is in urgent need of new solutions.


In the CNSL project, we are investigating whether a natural oil extracted from cashew nut shells can be used as a new, alternative pesticide.

– With the new, stricter regulations on pesticide use in the potato industry, there is a pressing need to develop alternative solutions. This is where biological agents, like the one we are testing in this project, can truly step in and save the day, says My Hemmeth Børjesen Livbjerg, Specialist at Danish Technological Institute.

Potato late blight challenges Danish potato growing

Potato late blight is a fungal disease that destroys potato plants. It is one of the primary reasons why potato growers lose crops or experience reduced yield.
When late blight ruins the harvest, much of the farmer’s labor, fertilizer, and energy consumption goes to waste. This also means that the climate impact per kilogram of potato increases. Therefore, there is an urgent need to find new, biological ways to protect potatoes.

Can cashew nut oil help?

– We want to investigate whether cashew nut shell oil can be used as a new pesticide in Denmark. The oil contains natural substances that, in trials abroad, have been shown to eradicate pests in various crops. The task will be partly to examine if it works, and partly to assess the effect the oil has on the plant, says Anders Lambæk, Consultant at Danish Technological Institute.

In this project, we are investigating three key areas:

  1. Does it work? How much oil is required to kill the fungus, when should it be sprayed, and does it work on different isolates of late blight?
  2. Does it work in practice? Can the oil be mixed and used in the spraying equipment farmers already own today?
  3. Is it safe? Does the oil harm the potato plants themselves and is there a risk of it leaching into the groundwater?

Four partners have divided the tasks between them

  • Aarhus University: Testing the oil in a laboratory to see exactly how it kills the fungus.
  • Danish Technological Institute: Testing the oil on potato plants in our controlled mesocosm facility. We are also examining whether the plants sustain damage and if the oil is environmentally safe.
  • Interfiller A/S: Blending and adapting the oil so it achieves the right formulation and can be used in farmers' spraying machinery.
  • Bigum Holding ApS: Main applicant and concept owner of the project.

What is the goal?

Once the project is completed, the results should show whether the cashew nut oil is effective and safe enough to proceed with developing a commercial product that farmers can purchase and use in the future.

Partners

  • Bigum Holding ApS
  • Danish Technological Institute
  • Aarhus University
  • Interfiller A/S