NIBIO og partnere lanserer SOLWeeds i Norge; øker avkastning og lønnsomhet for bønder.

Black nightshade causing major problems for Norwegian vegetable production - Nibio

Published: 10.08.2026 By: Erling Fløistad

Black nightshade causing major problems for Norwegian vegetable production

PhD fellow Lovisa Ek Hansson will spend the next three years studying the biology and development of nightshade species in Norwegian agricultural fields. Photo: Erling Fløistad

Nightshade weed species are becoming an increasing challenge for Norwegian potato and vegetable growers. NIBIO and several partners have now launched the research project SOLWeeds, which aims to develop new weed management strategies and reduce production costs for growers.

Black nightshade ( Solanum nigrum L.) is an alien species in Norway. Until around 1970, it was not considered a serious weed problem. However, over the past 50 years, the species has become an increasingly common weed in vegetable and potato production, particularly in root crops such as carrots.

Since the turn of the millennium, problems caused by black nightshade—and later also by other nightshade species—have continued to increase. Today, the greatest challenges are associated with black nightshade ( Solanum nigrum L.) and hairy nightshade ( Solanum physalifolium Rusby).

Why nightshade weeds are difficult to control

Nightshade species produce berries containing large numbers of seeds. The seeds survive passage through birds’ digestive systems and therefore spread easily to new areas. Once established in a field, the seeds remain viable in the soil for many years. This means that the nightshade problem does not disappear on its own.

According to the Norwegian Agricultural Extension Service (NLR), between 67 and 87 per cent of vegetable growers in southeastern Norway now have nightshade infestations in their fields.

“One reason nightshade species are particularly difficult to control is that they germinate late in the season,” explains NIBIO researcher Kirsten Tørresen.

“Early weed control, which is effective against many other weeds, therefore has limited impact. In addition, several herbicides that previously provided good control of nightshade are no longer approved.”

New project aims to find solutions

Tørresen is project leader for a new research project that started in February and will run for four years.

The SOLWeeds project aims to develop effective solutions based on both direct and preventive measures. Field trials will investigate strategies such as crop rotation, stale seedbeds, cover crops, non-chemical control methods and herbicide use.

In vegetable crops, the project will also test a robot that applies herbicides only to the weeds leaves.

“Our goal is to develop methods that make nightshade weeds easier to control. This will increase yields and improve profitability for growers,” says Tørresen.

Field trials have already started in Østfold County (potatoes, carrots and parsnips) and in Agder County (potatoes).

– I tillegg har vi ansatt en stipendiat, Lovisa Ek Hansson, som de neste tre årene skal fordype seg i søtvierartenes biologi og utvikling på norske jorder.

Rådgivere i Norsk Landbruksrådgiving forteller at flere produsenter allerede har valgt bort arealer eller gitt opp leiejord som er sterkt infisert med søtvier. Lukekostnadene har blitt så høye at produksjonen ikke er lønnsom. Tidlig gulrot og potet under plast er særlig utsatt.

– Søtvier er derfor ikke bare et agronomisk problem. Det er også et driftsøkonomisk og strukturelt problem for norsk matproduksjon, avslutter Tørresen.

Kirsten Tørresen Research Scientist - Division of Biotechnology and Plant Health

(+47) 971 80 114 kirsten.torresen@nibio.no Office Location: Ås H7

SOLWeeds is a four-year collaborative research project involving NIBIO (project owner), the Norwegian University of Life Sciences (NMBU), Luke (Finland), Aarhus University (Denmark), the Norwegian Agricultural Extension Service (NLR), growers and industry partners. SOLWeeds is funded by the Norwegian Research Funding for Agriculture and Food Industry, Grofondet, NLR, growers and other industry partners.

SOLWeeds is funded by the Norwegian Research Funding for Agriculture and Food Industry, Grofondet, NLR, growers and other industry partners.

Division of Biotechnology and Plant Health

SOLWeeds: Effektiv bekjemping av svartsøtvier og begersøtvier i grønnsaker og potet

Svartsøtvier (Solanum nigrum L.) og begersøtvier (S. physalifolium Rusby) er ugras som forårsaker store problemer for norske produsenter av grønnsaker og potet. Flere dyrkere mener at problemet og lukekostnadene er så store at de frykter de må redusere dyrka areal av f.eks. gulrot, eller stoppe produksjonen helt. I potet er spesielt tidligproduksjonen under dekke utsatt.

New study documents TFA runoff from a Norwegian agricultural catchment

TFA, a relatively little-known PFAS compound, is spreading in the environment. Researchers have now, for the first time, estimated how much is washed out of a Norwegian agricultural catchment over the course of an entire year.

Rare orchids find new homes in Telemark

This summer, several hundred laboratory-grown elder-flowered orchid (Dactylorhiza sambucina) plants will be introduced into traditionally managed hay meadows in Telemark, southeastern Norway.

Researchers agree: Regulations are hindering biological plant protection products

Despite promising research results, it can take up to ten years to obtain approval for biological plant protection products in the EU. Researchers experience that current regulations are designed for synthetic products and prevent new biological alternatives from reaching the market.

Nine facts about Norwegian agriculture

Norway’s agricultural landscape is undergoing a remarkable transformation. While milk consumption has halved over the past three decades, cheese and poultry have surged in popularity.

Representatives from the SOLWeeds partner organisations gathered for the project kick-off meeting at Ås (Akershus County) in February. Photo: Erling Fløistad