Invasive Japanese knotweed spreading in Jelgava, warns municipality
Jelgava's municipality has warned that the invasive Japanese knotweed plant is spreading across the city and is asking residents to report sightings. The plant is considered one of Europe's most aggressive invasive species and can damage infrastructure.
The Jelgava municipality has reported that Japanese knotweed, regarded as one of the most aggressive invasive plant species in Europe, is spreading within the city. The municipality shared the information with the LETA news agency.
Residents and landowners are being asked to report locations where the plant is growing to the municipality's operational information centre by calling 8787. The collected data will help build a more complete map of the plant's spread and will be passed on to the State Plant Protection Service (VAAD).
Where it has been found
According to information gathered by the municipality, the main areas of concern are around Slokas Street and Meiju Road, as well as the intersection of Meiju and Atmodas streets — mostly near infrastructure and traffic junctions.
Potential damage
The municipality warns that the plant can rapidly take over both neglected and partially maintained areas. Its powerful root system has been known to lift paving stones and even deform asphalt, potentially causing significant economic damage if left unchecked.
VAAD notes that Japanese knotweed (Reynoutria japonica) has been included on the European Union's list of invasive species since 17 June 2025. The agency is urging municipalities to monitor and control the plant on their own properties and, where possible, inform private landowners about the need to control it on their land.
Why eradication is difficult
The plant spreads through rhizomes and stem fragments, which can remain viable and produce new shoots, making complete eradication a lengthy process. Dug-up or cut plant parts should not be composted; they must be stored in sealed bags or containers for several months until no longer viable. After removal work, clothing, footwear and equipment must be cleaned, and soil that may contain viable rhizome fragments should not be moved. Treated areas need to be monitored for several more years, since new shoots can still appear.
Other knotweed species found in Latvia — Sakhalin knotweed and Bohemian knotweed — are also classified as invasive at the EU level, and growing them is prohibited.
