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Research & Development - Japanese Knotweed field trials

Background to physiochemical Japanese knotweed field trials by Mr. D. Jones

1) Rationale for field trial programme and the field trial locations:

Following extensive literature survey in 2010/2011, I decided that independent, large-scale field trials were required in order to investigate the effectiveness of a wide range of Japanese knotweed physiochemical control methods. It was also identified that the field trials should last for at least two years, in order that control method effectiveness can be assessed in the longer-term.

Once the initial parameters of the investigation were set, field trial sites were identified throughout the South Wales area. Following  exhaustive survey, three trial sites were identified; two smaller sites in Swansea (courtesy of Mr. S. Hathaway, City & County of Swansea) and a third, much larger site in Taffs Well, near Cardiff. In order to determine their suitability in terms of physical and ecological parameters,
extensive desk and field-based assessments were undertaken (e.g. historic landuse and protected species surveys) in order to confirm the suitability of the field trial sites for the field trial programme.

2) How we implemented the field trials:

Following desk and field-based assessments, treatments were rolled out at the Swansea field trial sites from April 2012. Three initial treatments were rolled out: 1) covering with geomembrane; 2) digging + Tordon 22K® + Glyfos Proactive® & 3) digging + Glyfos Proactive®.

Through 2012, treatments were assessed on an on-going basis (please see below) and the Taffs Well field trial site was prepared for all remaining treatments in 2013 – there are over 6km of paths between the treatment plots at the Taffs Well field trial site.

Mr. D. Jones is fully NPTC qualified and applied all chemical treatments (6 different herbicides) within the field trial programme, amounting to 20,475m2 of knotweed spraying in 2012 alone.

3) How we are assessing control on an ongoing basis across the three field trial sites in South Wales.

All treatments are monitored on an on-going basis, with photographic documentation of all 57 treatment plots at least once per month (March-October).

Additionally, annually full treatment plot assessments are undertaken, that include the following:

1. Above-ground knotweed growth parameters (e.g. stem height).

2. Below-ground knotweed growth parameters (rhizome viability).

3. Non-invasive measures of knotweed stress (leaf chlorophyll content).

4.  Vascular plant species diversity (knotweed percentage cover, compared with other treatment plots and surrounding

5.  Soil parameters (e.g. nutrient content)

Assessments at all three sites will continue on a monthly and annual basis until conclusion of the field trials.  

Main Research and Development Page
Field Trial Site 1
Field Trial Site 2
Field Trial Site 3 
General Observations


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