Enhancing Physiochemical Control of Introduced Petasites spp.

Dr Daniel Jones

Presentation Overview• Introduction to the target taxa• Petasites spp. – current control• Field trials – design & progress• Results & analysis• Further work

Introduced Petasites spp.• Genus Petasites (Asteraceae)

includes 19 species distributed across Eurasia, North America and Africa

• Naturalised representatives of the genus Petasites are locally significant Invasive Alien Plants (IAP) throughout the UK

• Socioeconomic impacts: - Nature conservation- Recreation and landscape

• Limited body of literature pertaining to introduced Petasites spp.

Winter heliotrope (Petasites fragrans) Welsh National Herbarium specimen

Introduced Petasites spp.• Petasites japonicus ssp.

giganteus, P. albus & P. fragrans are all horticultural introductions (ground-cover)

• Form dense, monospecific stands that shade out competitors

• All are herbaceous, rhizomatous, perennial geophytes

• Once established they can be difficult and costly to eradicate

Giant butterbur (P. japonicus ssp. giganteus)

(Adapted from Clement et al. 2005)

Introduced Petasites spp. – The Main Culprits

Giant butterbur(P. japonicus ssp. giganteus), Cardiff

(UK)

Winter heliotrope(P. fragrans), Cardiff (UK)

White butterbur(P. albus), nr. Cilycwm (UK)

UK Distribution of Introduced Petasites spp.

Winter heliotrope (P. fragrans)

White butterbur (P. albus)

Giant butterbur (P. japonicus ssp. giganteus)

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

Physical ControlCurrent practice

Summary of physical control methods (NRA 2012)

Chemical ControlCurrent practice

Summary of chemical control methods (NRA 2012)

Field Trial RationaleIdentified need for long-term (>3 years duration), controlled Petasites spp. field trials to:• Develop technical understanding of control

techniques• Formulate effective control methods• Enhance knowledge of control efficacy and

associated costs• Communicate knowledge RE methods and

efficacy to stakeholders

How Are We Testing?• Trialing 13 proven and novel control methods• Twenty-eight 1 m2 controlled field trial plots

(treatments in duplicate, except for covering and one control plot)

• Trial conducted at Taffs Well field trial site nr. Cardiff

Field Trial Site Location

Rhizome PhysiologyRhizome:• Rhizomes (roots) are robust &

extensive and are functionally similar• Root system >50 % total biomass• Majority of rhizome biomass is found

in the top 50 cm of the soil profile, though roots may extend >2 m depth

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

Image highlighting depth and extent of Winter heliotrope (P. fragrans) rhizome

network (Cardiff, 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 RelationsP. fragrans source-sink relations and implications for herbicide application

HerbicidesAAA inhibitor: • Glyphosate (Glyfos Proactive®) Synthetic auxin: • 2,4-D amine (Depitox®)• 2,4-D amine & dicamba

(Thrust®) • Triclopyr & clopyralid (Blaster®) • Aminopyralid & triclopyr (Icade®)• Aminopyralid & fluroxypyr

(Synero®)• Picloram (Tordon 22K®)

All herbicides were foliar / soil spray applied with:• Topfilm® surfactant• EasiMix® water conditioner

Field Trial Site Plan

Treatment Schedule

Treatment ScheduleSpring treatment window

Treatment ScheduleAutumn treatment window

ParametersTreatment patch data capture:• P. fragrans percentage (%) cover• Vascular plant species diversity

ObservationsTaffs Well

April 2014

Glyfos ProActive® 351 DAT [SPRING] 10.00 L ha-1 (3.60 kg AE ha-1) glyphosate

ObservationsTaffs Well

April 2014

Tordon 22K® 351 DAT [SPRING] 5.60 L ha-1 (1.34 kg AE ha-1) picloram

ObservationsTaffs Well

April 2014

Glyfos ProActive® 351 DAT [SPRING] 6.00 L ha-1 (2.16 kg AE ha-1) glyphosate

Glyfos ProActive® 351 DAT [SPRING & AUTUMN]

6.00 L ha-1 (4.32 kg AE ha-1) glyphosate

Glyfos ProActive® 351 DAT [AUTUMN]6.00 L ha-1 (2.16 kg AE ha-1) glyphosate

ObservationsTaffs Well

April 2014

Depitox® 351 DAT [AUTUMN]9.00 L ha-1 (4.50 kg AE ha-1) 2,4-D amine

Depitox® 351 DAT [SPRING]9.00 L ha-1 (4.50 kg AE ha-1) 2,4-D amine

ObservationsTaffs Well

April 2014

ObservationsTaffs Well

April 2014

Covering 239 DAT

Results & Analysis• Analysis of P. fragrans control efficacy• Full economic evaluation of all control methods• Community analysis of vascular plant data

Project Partners:

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