Optimising Physiochemical Japanese Knotweed Control

Optimising PhysiochemicalJapanese Knotweed Control

Dr Daniel Jones

Presentation Overview• Brief introduction to the target taxa• Knotweed control – current best

practice• Field trials – design & progress• Results & analysis• Further work

Japanese Knotweed1. Ecological impacts:• Reduced habitat availability and

quality• Disruption of terrestrial and

freshwater food webs (Gerber et al. 2008)

2. Socioeconomic impacts: • Built environment (e.g. development

sites)• Recreation and landscape (e.g.

angling)3. Control costs:• £165.6 million PA for UK• £8.8 million PA for Wales (Williams et

al. 2010)• In excess of £1.5 billion for complete

eradication in UK (Shaw et al. 2009)

Japanese knotweed (Fallopia japonica var. japonica) Welsh National Herbarium

specimen

Knotweed – The Main CulpritsJapanese knotweed stand (F. japonica var. japonica), Cardiff

(UK)

Dwarf knotweed stand (F. japonica var. compacta), Merthyr Tydfil

(UK)Bohemian knotweed stand

(F. x bohemica), Cardiff (UK)

Giant knotweed stand (F. sachalinensis), Cardiff (UK)

UK Distribution of Japanese Knotweed s.l. Taxa

Bohemian knotweed (F. x bohemica)

Giant knotweed (F. sachalinensis)

Japanese knotweed (F. japonica var. japonica and

compacta)

Available from: http://data.nbn.org.uk/

Physical ControlCurrent best practice

Summary of physical control methods (EA 2006)

Chemical ControlCurrent best practice

Summary of chemical control methods (EA 2006)

Despite proven ecological and socioeconomic impacts, we still do not know enough to make

good, evidence-based decisions

Field Trial RationaleIdentified need for large-scale and long-term field experiment (>3 years duration) to:• Test control efficacy of widely applied and

novel control methods• Investigate control method costs and

environmental impacts• Site restoration following knotweed control

How Are We Testing?• Largest knotweed control experiment ever

undertaken – sixty-five 225 m2 field trial plots• Greatest number of control treatments ever

trialled for control of a single invasive species – 24 currently under investigation

• One of the longest running invasive species field trials, worldwide (Kettenring & Adams 2011)

Field Trial Site Locations

Field Trial Site LocationsSite 1: Lower Swansea Valley Woods (LS),

Swansea

Field Trial Site LocationsAerial view of site 2013

Field Trial Site LocationsSite 2: Swansea Vale Nature Reserve (SV),

Swansea


Field Trial Site LocationsSite 3: Taffs Well (TW), nr. Cardiff


‘By their very nature chemical controls are self-defeating, for they have been devised and applied without taking into account the complex biological systems against which they have been blindly hurled.’

Rachel Carson (1962)

Knotweed Physiology

Rhizome PhysiologyRhizome:• Rhizomes (roots) are robust &

extensive and are functionally similar• Root system >65 % total biomass• Most found in the top 1m of soil,

though roots reported deeper than 4.5 m (Jones 2015)

• Rhizome can extend ≤20 m from the main stand and grow ≤3 m per year (Beerling et al. 1994)

Dispersal: • Rhizome fragments (diaspores)• Direct rhizome expansion (Bailey et

al. 2009)

Shoots emerging 10 m away from main stand

(Briton Ferry, Wales, UK)

Control Implications• Physical methods ineffective due to significant

energetic reserves – also encourage spread• Rhizome exhibits strong seasonal changes in

herbicide uptake • Deep rhizome is distant from the point of

herbicide application• Is there a herbicide dose-response

relationship?• Most herbicides formulated and tested on

annual plant species (e.g. synthetic auxins)

Source-Sink RelationsKnotweed source-sink relations and implications for herbicide application

Knotweed regrowth following glyphosate treatment (Cardiff: A = 14/07/09; B = 24/07/11)

HerbicidesALS inhibitor:• Flazasulfuron (Chikara®) PPO inhibitor: • Flumioxazine (Digital®)• Oxadiazon (Ronstar Liquid®) AAA inhibitor: • Glyphosate (Glyfos Proactive®) Synthetic auxin: • 2,4-D amine (Depitox®)• Aminopyralid & triclopyr (Icade®)• Aminopyralid & fluroxypyr (Synero®)• Picloram (Tordon 22K®)

Application Methods• Spraying• Stem injection• Cut & fill• Turning before herbicide

application• Cutting before herbicide

application

Knotweed excavation at Lower Swansea Valley Woods

Treatment Schedule

Treatment SchedulePre-emergent treatment window

Treatment ScheduleLate spring / summer treatment window

Treatment ScheduleLate summer / autumn treatment window

Testing Control Response• 225 m2 treatment area• 6× 4 m2 monitoring

patches, assigned at random

• Treatment plots were treated in their entirety

• Control plots received no treatment

Scale drawing of treatment plot

ParametersMonitoring patch data capture:• Aboveground knotweed growth parameters• Plant stress measures • Vascular plant species diversity • Soil parameters

Glyfos ProActive® 689 DAT10.00 L ha-1 (3.60 kg AE ha-1) glyphosate

Tordon 22K® & Glyfos ProActive® 797 DAT11.20 L ha-1 (2.69 kg AE ha-1) picloram &10.00 L ha-1 (3.60 kg AE ha-1) glyphosate

ObservationsLower Swansea Valley Woods

October 2014

Covering treatment 888 DAT

ObservationsSwansea Vale Nature Reserve

October 2014

ObservationsTaffs Well

October 2014

Spray alone (left) and cut with spray (right) Glyfos ProActive® 404 DAT

10.00 L ha-1 (3.60 kg AE ha-1) glyphosate


October 2014

Cut & fill (left) and stem injection (right) Glyfos ProActive® 407 and 389 DAT

244.44 & 180.89 L ha-1 (80.00 & 65.12 kg AE ha-1) glyphosate

Synero® & Glyfos ProActive® 508 DATSynero® 2 L ha-1 (0.06 kg AE ha-1 aminopyralid &

0.20 kg AE ha-1 fluroxypyr) & 10.00 L ha-1 (4.32 kg AE ha-1) glyphosate

Tordon 22K® & Glyfos ProActive® 568 DAT11.20 L ha-1 (2.69 kg AE ha-1) picloram &10.00 L ha-1 (3.60 kg AE ha-1) glyphosate


October 2014

Chikara® & Glyfos ProActive® 506 DAT25 % w/w (0.15 kg AE ha-1) flazasulfuron &


Chikara® & Glyfos ProActive® 568 DAT25 % w/w (0.15 kg AE ha-1) flazasulfuron &10.00 L ha-1 (3.60 kg AE ha-1) glyphosate


October 2014

Digital® & Glyfos ProActive® 508 DAT0.10 L ha-1 (0.03 kg AE ha-1) flumioxazine &


Ronstar Liquid® 223 DAT8.00 L ha-1 (2.00 kg AE ha-1) oxadiazon


October 2014

Results & Analysis• Data for 1st 3 years of field trials now in publication, forming

the basis of best practice guidance for:- Royal Institute for Chartered Surveyors (RICS) and - Property Care Association (PCA)• Full economic evaluation and Life Cycle Assessment (i.e. CO2

emissions) of all control methods• Community analysis of vascular plant data• Soil analysis (physical, chemical & biological)

Further Work• Treatment of Himalayan balsam underway• Expansion of field trial programme to include:- Additional herbicides- New application technologies- Test efficacy of widely applied and novel physical

eradication methods

Informing Industry• Experimental data (supporting evidence) are

essential for informing Integrated Plant Management (IPM) control strategies

• Such data reduce operational costs and environmental impacts, increasing sustainability

• In the face of increasing pesticide deregulation, studies such as these form an essential source of evidence for regulators

• Consolidation in Ag industry will make it more important for industry to find solutions in concert with universities

Project Partners:

Part-funded by the European Social Fund (ESF) through the Welsh Government with Swansea University and Complete Weed Control Ltd.

Project Acknowledgements:

Environment

Optimising Physiochemical Japanese Knotweed Control