Weeds of National Significance

National Willows Program

WILLOWS WORKSHOP

Supported by the State Government of Victoria.

• National, state and regional context

• Willow identification

• Willow sawfly in Australia

• Update regional maps highlighting where willows occur

Workshop Game Plan

Willows - a Weed of National Significance

• Infest 1000s of km of waterways

• Approx. $30 million spent annually

• > 32 types of willows

• Spread in different ways

• Distribution, invasiveness and impacts of specific

willows are poorly understood

Did you know?

Q: Do willows consume more water than natives?

Clue: it depends on where they are in the landscape

A: Yes: if growing in the water No: if growing on the bankCan consume approx. 3 megalitres per crown hectare more water than river red gums

WILLOWWILLOWIMPACTS?IMPACTS?

Primary production altered (algae)

Nutrient transfer

Leaf litter input

Aquatic food webs

Increased shading of stream

Obstruct and divert floods

Erode Riverbanks

Sediment trapping around roots

Change in vegetation & structure

Terrestrial insects

Change in higher trophic

orders

Emergent stream insects

Q: When sitting along a river, lazily fishing, how might you accidentally grow a new willow tree?

Clue: what do you lean your fishing rod on?

A: Stick a willow stem in the ground as a fishing rod holderWillows grow easily from stems

How do you grow a willow?

How do willows spread?

Seed up to 100km

Twigs and branches

Layering

Salix nigra Salix nigra (black willow)(black willow)e.g. North East Victoriae.g. North East Victoria

Salix cinerea Salix cinerea (grey sallow)(grey sallow)

e.g. Sydney catchmente.g. Sydney catchment

Spread by seed

Early detection and eradication of Early detection and eradication of seeding willows in Tasmaniaseeding willows in Tasmania

Don’t respect our borders

National Willows Taskforce

SA

CMAs

Weeds CRC

ACT

NSW

Tas

Community

NGIA

QldLocal gov’t

VicCommunity

Did you know?

Q: For what religious festivals are willows allowed to still be imported?

Clue: they can be imported from Israel and the U.S.A

A: Jewish festivals

‘cut flowers and foliage’

‘only Rabbis may import the cuttings’One of the Four Kinds taken on Sukkos: “The

willow, which is inedible and lacks aroma as well, represents those people lacking both in Torah and good deeds”

National Willows Program

• National policy on importation – to prevent future problems

• Biological control and other research– protecting our investment for the future

• Education / awareness / communications– National Best Practice Management Guide– Nursery and Garden Industry– Increasing broad public awareness

• Mapping and weed risk assessment – can’t manage what we don’t know

Developing willow management priorities

• Workshops

– create/update regional maps

– training in mapping, sawfly and ID

• Weed risk assessment

– risk, impacts, current and potential distribution and

feasibility of control

• Priority actions for willow management

– reports to each state and CMA/NRM region

– maps of distribution and potential spread

Find out more...

Website:

www.weeds.org.au/WoNS/Willows

National Willows Network

nationalwillowsnetwork@lists.weeds.org.a

u

Willow Strip Newsletter

Weeds of National Significance

WILLOW MAPPING

Supported by the State Government of Victoria.

Why map willows?

Because you can’t manage what you don’t know!

North East bushfiresNorth East bushfires

TasmaniaTasmania

E.g. Wingecarribee E.g. Wingecarribee SwampSwamp

Why map willows?

• Eradication of all willows not feasible or desirable

• Need to set priorities for management

• Factors to consider:

– Risk of further spread by seed or branches

– Current impacts

– Density and location of willows

– Accessibility and cost of management

– Community support

Did you know?

Q: What industry in South Australia is impacted by willows growing along the River Murray?

Clue: they float on water

A: Houseboating IndustryNowhere to moor the boats in some sections

Weed risk management

• Weed risk is based on:

– invasiveness (rate of spread)

– impacts

– current and potential distribution

Weed risk management

• One willow may rank more highly than another

willow if:

– its overall area and / or the number of ecosystems it

can invade is greater (invasiveness);

– it impacts more on social, environmental and

agricultural values (impacts)

– it is presently localised - but could spread much

further (current:potential distribution)

Feasibility of coordinated control

• Total cost is a function of:

– total area infested,

– annual control cost per unit area and

– number of years required to achieve the desired

level of control.

Current : potential distribution

Potential Distribution

Sample maps

Australian climate matchSalix aegyptiaca

Australian climate match Salix fragilis