Environmental weed risk assessments

Page last updated: Friday, 14 October 2022 - 2:33pm

Please note: This content may be out of date and is currently under review.

Introducing new plants to an area may have both positive and negative effects on the environment, economy and community. To minimise the negative environmental impact of introducing new agricultural species, we use a risk assessment procedure based on widely accepted scientific standards.

Why assess environmental weed risk for introduced plants?

Agriculture in Australia is based largely on exotic or non-indigenous plants, however there is a well-documented history of introduced plants becoming environmental weeds. A number of plants introduced for agriculture have spread from sown areas and become serious environmental weeds. For example, Gamba grass (Andropogon gayanus) was introduced into the Northern Territory as a pasture species but has subsequently become a serious environmental weed as the large biomass greatly increases the intensity of fires (note: Gamba grass is a prohibited import into Western Australia).

The information on this page is of particular relevance to pastoralists as a diversification permit from the Pastoral Lands Board (PLB) is required to grow any non-indigenous (exotic) species on pastoral leasehold land. However, the weed risk is not confined to certain land tenures, so all landholders in northern Western Australia (WA) are encouraged to be aware of the potential of species they sow or cultivate to become weeds of the natural environment and to take appropriate measures to minimise the risk.

In this context, ‘non-indigenous’ refers to any species not indigenous to WA. There is no need to apply for a diversification permit for species that are endemic (i.e. native) to WA. This can be checked using Florabase.

How we assess environmental weed risk

The environmental weed risk assessment of a species is assessed for three regions in the pastoral zone of WA (Kimberley, Pilbara, Gascoyne-Goldfields; Figure 1) using a three-step process (Figure 2).

Step 1: Species prerequisites for WRA

Non-indigenous species or specific varieties may undergo post-border weed risk assessment after checking that each of the proposed species is:

  • permitted entry into Australia
  • not a Weed of National Significance (WoNS)
  • not listed as a WA prohibited organism (s12) or a declared pest (s22) on Western Australian Organism List (WAOL).
  • either listed as a permitted organism (s11), or a permit has been granted for its import (r73) on WAOL.

If a proposed species is not listed as a prohibited organism, declared pest or permitted organism on WAOL, the applicant/importer can lodge an ‘Application for Import Permit’ with DPIRD.

Step 2: A filter

The second step is a ‘filter’ to identify species which are:

  • recorded as environmental weeds in similar environments in Australia or overseas and,
  • likely to persist in the given environment without management.

Species with a ‘negative’ response to both filters represent a negligible to low environmental weed risk in the pastoral zone.

Step 3: Full environmental weed risk assessment

For all other species, an environmental weed risk assessment (WRA) is undertaken using the ‘Environmental weed risk assessment protocol for growing non-indigenous plants in the Western Australian rangelands’ (Moore et al. 2022) which is based on the methodology developed by the Future Farm Industries Co-operative Research Centre (FFI CRC) WRA for southern Australia (Stone et al. 2012). DPIRD Bulletin 4924

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Figure 1 The three regions within the pastoral zone of Western Australia plus the agricultural area

 

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Figure 2 Flow diagram showing the three-step assessment process

Note: *For all organisms listed on WAOL under s11 of the Biosecurity and Agriculture Management Act 2007 or r73 of the Biosecurity and Agriculture Management Regulations 2013.

**The ‘environment’ can be considered in the context of the WA Rangelands and the three regions (Kimberley, Pilbara, Gascoyne-Goldfields), or for a specific application within a single Region.

***Without management, means without any fertiliser, Rhizobia, irrigation, grazing management or control of competition from other species.

The WRA protocol is subdivided into three sections where:

  • invasiveness – assesses the ability of a species to spread beyond agricultural systems or grazed native vegetation into intact native vegetation
  • impacts – assesses the potential detrimental impacts a species may have on intact natural ecosystems
  • potential distribution – assesses how widely adapted is the species to the novel environment based on the climate and soils of the target area.

Weed risk score calculation

The first 2 sections of the protocol contain a series of questions that will generate a score depending on the response given. The scores for each question are then summed and standardised (maximum score of 10 for each section).

The adjusted scores for each section are then multiplied by the potential distribution score (maximum score of 10) to arrive at the overall weed risk score (equation 1).

Equation 1: Weed risk score = Invasiveness (0–10) x Impacts (0–10) x Potential distribution (0–10)

The weed risk category is then determined from the weed risk score (Table 1).

Example: For species X with an invasiveness score of 6.2, an impacts score of 3.2 and a potential distribution score of 4.4, the risk score equals 6.2 x 3.2 x 4.4 = 87.3, which equates to a medium risk rating.

The environmental weed risk assessment scores for the Kimberley, Pilbara and Gascoyne-Goldfields (includes Gascoyne, Murchison and Goldfields) regions are listed in Table 2.

Table 1 Weed risk scores and corresponding risk rating

Weed risk score

Risk rating

Possible conditions on a diversification permit

≥236

Very high

In general, unlikely to be approved, however if approved the PLB may include additional conditions

112–235

High

If approved the PLB may include additional conditions

50–111

Medium

Standard conditions

0–49

Negligible to low

Standard conditions

Source: Future Farm Industries (FFI) CRC; Stone et al. (2012)

Environmental weed risk ratings for species for three regions within the pastoral zone of WA

Plants are listed alphabetically in ‘species’ order:
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

Note: The species name hyperlink opens a PDF of the weed risk assessment for that species. Blank cells means that an assessment has not been done or is currently in preparation.

Table 2 Environmental weed risk ratings for species for three regions within the pastoral zone of WA assessed using the ‘Environmental weed risk assessment protocol for growing non-indigenous plants in the Western Australian rangelands’ (Moore et al. 2022) which is based on the FFI CRC Methodology. Species native to WA have not been included.
Species name Common name Gascoyne-Goldfields Pilbara Kimberley

Acroceras macrum

Nile grass

Negligible to low

Negligible to low

Negligible to low

Allium cepa

common onion

Negligible to low

Negligible to low

Negligible to low

Alysicarpus vaginalis

Alyce clover

Negligible
to low

Negligible
to low

Medium

Arachis glabrata

peanut prime

Negligible
to low

Negligible
to low

Negligible
to low

Arachis pintoi

peanut pinto

Negligible
to low
Negligible
to low
Negligible
to low

Asparagus officinalis

asparagus

Negligible
to low
Negligible
to low
Negligible
to low

Avena sativa

oats

Negligible
to low
Negligible
to low
Negligible
to low

Beta vulgaris

fodder beet, beet

Negligible
to low
Negligible
to low
Negligible
to low

Bothriochloa insculpta

creeping bluegrass

 

 

 

Bothriochloa pertusa

Indian bluegrass

Negligible
to low
Negligible
to low

High (>450mm)

Brassica napus

canola, oilseed rape

Negligible
to low
Negligible
to low
Negligible
to low

Brassica rapa

turnip

Negligible
to low
Negligible
to low
Negligible
to low
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Species name Common name Gascoyne-Goldfields Pilbara Kimberley

Cajanus cajan

pigeon pea

Negligible
to low

Negligible
to low
Negligible
to low

Cenchrus americanus

pearl millet

Negligible
to low

Negligible
to low
Negligible
to low

Cenchrus ciliaris

buffel grass

TBD

Very high

Very high

Cenchrus clandestinus

kikuyu

Negligible
to low
Negligible
to low
Negligible
to low

Cenchrus purpureus

elephant grass

Negligible
to low
Negligible
to low
Negligible
to low

Cenchrus setiger

Birdwood grass

TBD (>200mm)

High

High

Centrosema brasilianum

Brazilian centro

Negligible
to low
Negligible
to low
Negligible
to low

Centrosema pascuorum

centro

Negligible
to low
Negligible
to low
Negligible
to low

Chamaecrista rotundifolia

Wynn cassia, roundleaf cassia

Negligible
to low
Negligible
to low
Negligible
to low

Chloris gayana

Rhodes grass

Negligible
to low
Negligible
to low

High (>550mm)

Cicer arietinum

chickpeas

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Cichorium intybus

chicory

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Citrullus lanatus

watermelon

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Citrus reticulata

mandarin

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Citrus x limon

lemon

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Citrus x paradisi

grapefruit

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Citrus x sinensis

orange

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Clitoria ternatea

butterfly pea

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Medium (>400mm)

Cucumis melo

rockmelon

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Cucurbita argyrosperma

cushaw pumpkin

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Cucurbita maxima

squash, gourd

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Cucurbita moschata

squash

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Cucurbita pepo

marrow, pumpkin

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Cynodon dactylon

couch grass

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Very high (>550mm)

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Species name Common name Gascoyne-Goldfields Pilbara Kimberley

Dactylis glomerata

cocksfoot

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Daucus carota

cultivated carrot

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Desmanthus virgatus

desmanthus

Negligible
​​​​​​​to low

Medium

High

Desmodium heterophyllum

hetero

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Medium

Desmodium intortum

greenleaf desmodium

Negligible
​​​​​​​to low

Negligible
​​​​​​​to low

Medium (>800mm)

Dichanthium annulatum

Sheda grass

 

 

 

Dichanthium aristatum

Angleton grass

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Digitaria eriantha

digit grass, pangola grass

Negligible
​​​​​​​to low

Negligible
​​​​​​​to low

Medium

Digitaria milanjiana

finger grass

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Medium

Dimocarpus longan

lychee, longan

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Echinochloa esculenta

Japanese millet

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Eragrostis curvula

African lovegrass

Very high

Very high

High

Eucalyptus polybractea

Blue-leaved mallee

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Festuca arundinacea

tall fescue

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Ficus carica

figs

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
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Species name Common name Gascoyne-Goldfields Pilbara Kimberley

Glycine max

soybean

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Gossypium barbadense

cotton

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Gossypium hirsutum

cotton

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Helianthus annuus

sunflower

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Hordeum vulgare

barley

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Ipomoea batatas

sweet potato

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Lablab purpureus

lablab

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Leucaena collinsii
(assessed for sterile leucaena
breeding program)

leadtree

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Leucaena confertiflora
(assessed for sterile leucaena
breeding program)

leadtree

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Leucaena cuspidate
(assessed for sterile leucaena
breeding program)

leadtree

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Leucaena diversifolia
(assessed for sterile leucaena
breeding program)

leadtree

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Medium

Leucaena esculenta
(assessed for sterile leucaena
breeding program)

guaje

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Negligible
​​​​​​​to low

Leucaena greggii
(assessed for sterile leucaena
breeding program)

gregg leadtree, guajillo

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Negligible
​​​​​​​to low

Leucaena lanceolata
(assessed for sterile leucaena
breeding program)

leadtree

Medium

Very high

Very high

Leucaena leucocephala

leucaena, coffee bush

TBD (>250mm)

High

Very high

Leucaena macrophylla
(assessed for sterile leucaena
breeding program)

leadtree

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Medium

Leucaena pallida
(assessed for sterile leucaena
breeding program)

leadtree

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Leucaena pulverulenta
(assessed for sterile leucaena
breeding program)

great leadtree

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Leucaena retusa
(assessed for sterile leucaena
breeding program)

littleleaf leadtree

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Leucaena shannoni
(assessed for sterile leucaena
breeding program)

guaje

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Leucaena trichandra
(assessed for sterile leucaena
breeding program)

lobadaviyia

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Leucaena trichodes
(assessed for sterile leucaena
breeding program)

beranero

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Lolium multiflorum

Italian ryegrass

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Lolium perenne

perennial ryegrass

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Lolium rigidum

annual ryegrass

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Lotus corniculatus

birdsfoot trefoil

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Lotus uliginosus

greater lotus

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Lupinus angustifolius

narrowleaf lupins

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
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Species name Common name Gascoyne-Goldfields Pilbara Kimberley

Macroptilium atropurpureum

siratro, atro

TBD

Very high

Very high

Macroptilium bracteatum

burgundy bean

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Mangifera indica

mango

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Medium

Medicago littoralis

strand medic

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Medicago orbicularis

button medic

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Medicago polymorpha

burr medic

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Medicago sativa

lucerne, alfalfa

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Medicago scutellata

snail medic

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Medicago truncatula

barrel medic

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Megathyrsus maximus

panic grass

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

High (>650mm)

Moringa oleifera

moringa

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

High

Neonotonia wightii

glycine

Very high

Very high

Very high

Ornithopus sativus

French serradella

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
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Species name Common name Gascoyne-Goldfields Pilbara Kimberley

Panicum coloratum

Bambatsi panic

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

High (>400mm)

Passiflora edulis

passionfruit

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Phalaris aquatica

phalaris

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Phoenix dactylifera

date palm

Negligible
​​​​​​​to low

Negligible to medium (niche)

Negligible to medium (niche)

Plantago lanceolata

plantain

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Prunus persica

peach

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Puccinellia ciliata

puccinellia

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Raphanus sativus

radish (vegetable)

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Salvia hispanica

chia

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Santalum album

Indian sandalwood

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Secale cereale

cereal rye, rye

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Sesamum indicum

sesame

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Solanum tuberosum

potato

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Sorghum bicolor

hybrid forage sorghum

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Sorghum x almum

perennial sorghum

TBD

Medium

High

Stylosanthes guianensis
var. guianensis

common stylo

Negligible to low

Negligible to low

High (>500mm)

Stylosanthes guianensis
var. intermedia

fine stem stylo

Negligible to low

Negligible to low

High (>500mm)

Stylosanthes hamata

Caribbean stylo, (Verano)

Negligible to low

Medium (>350mm)

Medium

Stylosanthes scabra

shrubby stylo, (Seca)

Negligible to low

Medium (>350mm)

Medium

Stylosanthes seabrana

Caatinga stylo

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
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Species name Common name Gascoyne-Goldfields Pilbara Kimberley

Tamarindus indica

tamarind

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Trifolium alexandrinum

Berseem clover

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Trifolium michelianum

balansa clover

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Trifolium pratense

red clover

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Trifolium repens

white clover

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Trifolium resupinatum

Persian clover

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Trifolium subterraneum

subterranean clover

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Trifolium vesiculosum

arrowleaf clover

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Triticum aestivum

wheat

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Urochloa decumbens

signal grass

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

High (>900mm)

Urochloa humidicola

humidicola

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Medium

Urochloa mosambicensis

sabi grass

Negligible to low

Medium (>350mm)

High

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Species name Common name Gascoyne-Goldfields Pilbara Kimberley

Vaccinium corymbosum

blueberry

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Vaccinium corymbosum x
V. ashei x V. darrowi

blueberry hybrids

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Vicia faba

faba bean

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Vicia sativa

vetch

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Vicia villosa

woolly pod vetch

Negligible
​​​​​​​to low
Negligible
​​​​​​​to low
Negligible
​​​​​​​to low

Vigna radiata

mung bean

Negligible to low

Negligible to low

Negligible to low

Vigna unguiculata

cowpea

Negligible to low

Medium (>300mm)

Medium

Vitis vinifera

grapevines

Negligible to low

Negligible to low

Negligible to low

Zea mays

corn, maize

Negligible to low

Negligible to low

Negligible to low

 

References

Moore G, Munday C, Barua P (2022) ‘Environmental weed risk assessment protocol for growing non-indigenous plants in the Western Australian rangelands’, Department of Primary Industries and Regional Development, Bulletin no. 4924, Perth.

Stone L, Munday C, Bettink K (2012) ‘Environmental weed risk assessment protocol’ Future Farm Industries CRC Weed Risk Assessment.

Contact information

Papori Barua
+61 (0)8 9368 3267
Geoff Moore
+61 (0)8 9368 3293

Authors

Papori Barua
Geoff Moore