Lily growers in Drenthe have cut active substance use by 60% in four years — from 114kg per hectare in 2020 to 46.5kg in 2024, according to Statistics Netherlands — and a UV-C robot now on trial in Hijken is intended to push the figure lower still.

Since July, a 1.5m-wide Wagus machine from Spanish manufacturer Agrikola has been waking each evening at Veninga Hijken Bloembollen BV. As soon as darkness falls, the battery-powered cart drives over three pre-programmed lily beds at 1.5 to 2 km/h, its downward-facing UV-C lamps aimed at destroying botrytis spores before they enter the plant. HLB, a research institute based in the village of Wijster, runs the trial for the growers' group De Drentse Lelie. Researcher Ben Seubring leads the work.

Why UV-C and not fungicides?

UV-C light damages the DNA of micro-organisms, rendering bacteria, viruses and fungi harmless. Seubring sees precedent for the approach. "There have already been positive tests with onions in Spain and grapes in France," he said. "So why not here in lilies? The UV light shines on the crop and in doing so controls the fungus that occurs in the lilies."

The nightly UV-C pass is compared against a weekly fungicide spray and against beds receiving neither spray nor light. That three-way design, Seubring cautions, makes firm conclusions difficult. Varietal differences in botrytis susceptibility muddy the comparison. Dry weather kept disease pressure low this season. And the Wagus only arrived in Hijken in July, whereas maximum effect requires treatment from April.

No verdict yet, then. But first impressions give cause for optimism, and the experiment continues next year.

What is the target?

Lily cultivation ranks among the most spray-intensive agricultural sectors in the Netherlands. Campaign groups want crop protection use reduced further; some want the crop phased out entirely. The recent decline reflects reduced mineral oil use and legal bans on stronger chemical fungicides such as mancozeb.

Gert Veninga of Veninga Hijken sets the bar for the group's 17 growers. "What we as Drenthe growers want is to bring the use of crop protection products in lilies into line within 3 years with that in onions, potatoes and sugar beet," he said. "I am talking about the total of fungicides, herbicides and insecticides: in the region of 20–25kg of active substance per hectare per year."

That would mean roughly halving current use. Seubring calls the initiative a unique collaboration among growers around a new technology that leads to accelerated sustainability.

Is the robot alone enough?

No. Veninga names two further routes. "We are also increasingly working with a DSS to spray only when necessary," he said, referring to a Decision Support System. "And we are going to look more closely at the botrytis susceptibility of the varieties we grow."

The Wagus itself showed practical shortcomings in year one. Castor wheels at the front caused occasionally unstable driving behaviour. In wetter conditions, the tractor-pattern drive wheels proved too small. The machine carries two sets of two batteries, navigates by RTK-GPS once dark falls, and connects to the internet via Starlink satellites. It works only at night, because UV-C delivers maximum effect in darkness.

What should growers watch next?

Agrikola is represented in the Netherlands by Clean Light in Dordrecht. The 1.5m-wide version costs €17,000. The question of optimal night-time operation will be investigated more thoroughly in 2027. Meanwhile, HLB's trial resumes next spring — and with an April start, the second year should give growers the first real read on whether UV-C can substitute for a weekly fungicide pass.