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Knotweed Surveys Along the Motueka River

Kūmānu has been supporting Tasman District Council with surveys to identify sites where knotweed (Fallopia spp) is present along the Motueka River. 

Knotweed is listed as an eradication pest in the Tasman–Nelson Regional Pest Management Plan (RPMP). The species spreads readily through river systems and can form dense stands that outcompete native vegetation, alter riverbank stability, and reduce habitat values along waterways. 

This work has focused on both the upper and lower Motueka River following the significant flooding that occurred in July 2025. 

Large flood events can redistribute plant material through river systems, and in the case of knotweed, small root or stem fragments can establish new infestations downstream.

The survey programme has helped build a clearer picture of where knotweed occurs within the river corridor and provides important information to support future management planning. 
Location: Richmond, Tasman
Client: Tasman District Council

Services:
The survey work has been led by Kūmānu Ecologists David Cook and Mike Orchard, with support from our awa technicians and biosecurity field staff. Their combined experience in river ecology, plant identification, and field survey techniques has been central to developing an accurate understanding of knotweed distribution within the Motueka catchment.

A collaborative approach has also been taken to data collection in the field. 

The Tasman District Council pest inspection layer has been integrated into Kūmānu’s field mapping application, allowing survey data to be entered directly into the council dataset during field work. 

This approach improves efficiency, reduces duplication, and ensures that new observations are captured quickly and consistently within the shared system. 

Kūmānu is pleased to support Tasman District Council in building the knowledge needed to inform future management decisions for knotweed within the Motueka River system.

Care and capability in action. 

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