Transcript PROCEDURES FOR WEED RISK ASSESSMENT

THE NEED FOR WEED RISK
ASSESSMENT
Ricardo Labrada
320.000 Species
Examples of major weeds introduced in different regions
Species
Coming from
World Regions
Sorghum halepense (L.) Pers.
Mediterranean
Americas
Cynodon dactylon (L.) Pers.
Near East
Americas
Rottboellia
cochinchinensis(Lour.)
Clayton
Southeast Asia
North and Central
America and Caribbean
Chromolaena odorata (L.)
R.M. King & H. Robinson
Central America and
the Caribbean
Africa South of Sahara,
Asia & Pacific
Parthenium hysterophorus L.
Central America and
the Caribbean
Ethiopia, South Asia &
Australia
Prosopis juliflora L.
North America
Near East, East &
Southern Africa, &
Australia
Eichhornia crassipes
South America
North and Central
America and Caribbean
Africa, Asia & Pacific
Magnitude of the problem
• There are 260 000 plant species worldwide
• 10 000 are weeds
• 4 000 species have been exchanged among the
continents (introduced as exotic weeds)
• One can assume that there are still 6 000 species
waiting for their exchange (plants without any
history as weeds out of their known natural
habitat).
What is weed risk assessment?
•
•
Weed risk assessment (WRA) is the use of standard
technical criteria to determine the relative weed
threats posed by plant species (Virtue and Panetta,
2002).
Such a risk assessment is normally based on pest
risk analysis (PRA) prepared and accepted by the
IPPC, which consists of three stages:
1.
2.
initiating the process for analyzing risk
assessing pest risk
3.
managing pest risk
How to conduct weed risk
assessment?
Persons
Pathways
Weed Risk
Assessment
Habitats
Plants
Weed Risk Assessment is only one technical part
of the pre-entry decision-making process
Potential
economic
benefits
Potential
weed
risks
Risk &
benefits
assessed
Accept the
risk
Decision
“Political Input”
Reject the
risk
Pre-Entry Risk Assessment
Content of the procedures
• The procedures for weed risk assessment are concerned
primarily with preventing the entry and initial spread of plant
species that are likely to become pests within a country, or
which are there and ought to be considered pests.
• They describe the responsibilities of all participants in the
process of plant importation required to halt the spread of
weeds.
• The procedures are based primarily on the experience of
Australia and New Zealand, two countries that have effective
quarantine protocols for preventing the introduction of and
spread of unwanted plant species.
Pathways of entry
Plants may be introduced into countries via 3 main pathways
that will vary between countries according to their economies
and the flow of trade goods and people:
Introductions made intentionally
1. Plant imports for urban and/or commercial horticulture, or forestry. In
several countries these purposeful introductions have been responsible for
more than half the exotic weed flora.
Introductions made unintentionally
2. Via contaminated goods and products, such as seeds for sowing or
consumption by humans or livestock. This pathway is the easiest to
monitor because much attention is already paid to such products owing to
their potential to spread diseases.
3. Strictly accidental introduction of plants not included in either of the above
pathways e.g., attached to clothing. It is actually the least important.
Authorities need to determine the relative risk of these
pathways in each country.
The process of weed-risk assessment
• The most effective legislative framework to prevent the entry
of new weeds is the concept of a Permitted List of plant
species (or defined taxa).
• If a taxon with the potential to be a pest in an area is not on a
list of taxa permitted to be in that area, then it will be
prohibited until it has been determined whether it is potential
quarantine pest.
• A formal weed-risk assessment is part of that process. All
plants not present in the country i.e., exotic, are deemed to be
prohibited until they have undergone assessment.
• By systematically undertaking weed-risk assessments,
countries will develop lists of species that are either permitted
entry and those that are prohibited.
Scoring for Weed Risk Factors (critical score = 6)
Aquatic plant ?
Other members of the genus are weeds ?
Propagules likely to be dispersed intentionally or
unintentionally by human activity?
Produces spines, thorns or burrs?
Parasitic?
Unpalatable or toxic to grazing animals?
Host for recognised pests and pathogens?
Causes allergies or otherwise toxic to humans?
Climbing or smothering growth habit?
Produces viable seed?
Seed persists for > 1 year?
Reproduction by vegetative propagation?
Tolerates or benefits from mutilation, cultivation, or fire?
Y=3
Y=2
Y=2
Y=1
Y=1
Y=1
Y=1
Y=1
Y=1
Y=1
Y=1
Y=1
Y=1
NB Where the status of a risk factor is unknown, it should be scored as a ‘yes’.
Post-entry risk management
When Should Risk Assessment be
conducted?
A species can be assessed:
Pre-entry
1. When it is out of the area of interest area.
2. When it is arriving or entering the new
territory.
Quarantine
Post-entry management
3. When it is established.
4. When it is spreading.
The procedure on Post-border Weed Risk
Management
• It has a systematic process of six steps:
Step 1 is establishing the weed risk management context:
overall goal/s, stakeholders, existing legislation and resources
to undertake the WRM.
Step 2 is identifying the weed risk candidates. Plant species
for WRA are determined from collating existing weed lists,
surveillance to detect new species and/or review of likely
incursions.
Step 3 is analysing and evaluating weed risks. Comparative
weed risks are scored and categorised using a WRA system
that incorporates the three key criteria of Invasiveness,
Impacts and Potential Distribution.
Invasiveness
•
Invasiveness is a relative index of the rate of spread of a
weed, and encompasses the factors of establishment,
reproduction and dispersal.
•
Direct measurement of rate of spread is difficult, and
requires sequential data over many years. There are three
key factors for Invasiveness:
1. weed's ability to establish amongst existing
vegetation.
2. weed's reproductive ability (germination process,
reproduction by seeds or other propagules).
3. weed's dispersal ability (intervening factors, wind,
water, flying and ground animals, human dispersal,
vehicles, and produce or by-products contaminant).
The Impacts
•
The procedure focuses on the effects of naturalised
plants, and consider six factors, i.e. the degrees of weed
to reduce, restrict or affect:
1.
2.
3.
4.
5.
Establishment of desired plants
The biomass/yield of desired plants
The quality of products or services
Physical movement
Human and/or animal health
6.
Ecosystem processes
Potential Distribution
•
Potential distribution is the total area at risk if a weed were
to spread uncontrolled.
•
•
•
It is best predicted using maps in a GIS framework.
Predictions should be conservative and only include areas
where the weed is likely to have significant impacts.
The steps in determining Potential Distribution are:
1.
2.
3.
World distribution data for the weed
Climate modelling
Soil tolerances
4.
Land uses at risk
4-6 Steps
• Step 4 is for analysing and evaluating feasibility of
coordinated control. Comparative feasibility of
coordinated control programs are scored and categorised using
a system that incorporates the three key criteria of Current
Distribution, Control Costs and Duration.
• Step 5 is for determining weed management
priorities. Such actions include preventing entry,
eradication, containment and improving targeted control
techniques.
• Step 6 is for implementing weed management
actions, based on the priorities determined above. This is the
transition from the strategic planning stage of WRM to
operational, on-ground programs.
WEED
RISK
Stage 5 OF
– Determine
Weed
FEASIBILITY
COORDINATED
CONTROL
Management Priorities
Low
Medium
High
No action
No action
Monitoring
Medium
General improvement
of weed management
General improvement
of weed management
and local
containment
Prevent the entry and
regional
containment
High
Direct management
including Biocontrol
and local
containment
Direct management,
regional containment
and
Local Eradication
Prevent entry and
regional eradication
Low
Post –border Weed Risk System
Southern Australia
Comparative
weed risk =
Containment
Feasibility =
Invasiveness
(0-10)

Impacts
(0-10)

Potential Distribution (0-10)
Control Costs (0-10)

Real Distribution
(0-10)

Persistence (0-10)
Post –border Weed Risk System Southern Australia
CONTAINMENT FEASIBILITY
WEED
RISK
No
significativ
e
>13
No significative
>13
Low>56
NO ACTION
NO ACTION
Medium
<101
High >14
Very High
<14
NO ACTION
MONITORING
MONITORING
PROTECT THE
SITES
NO ACTION
Low
<39
Medium
>31
NO ACTION
NO ACTION
NO ACTION
MANAGE THE
SITES
MANAGE THE
SITES
MANAGE THE
SITES
PROTECT THE
SITES
EXPANSION
CONTAINMENT
High
<192
Very High
>192
MANAGE
WEED
MANAGE
WEED
MANAGE
WEED
PROTECT THE
SITES
& MANAGE
WEED
PROTECT THE
SITES
EXPANSION
CONTAINMENT
DESTROY
INFESTATIONS
EXPANSION
CONTAINMENT
DESTROY THE
INFESTATIONS
ERADICATE IN
THE REGION
• Any of these procedures can be modified and
improved either locally or at a regional level
once the countries use them and see their
limitations.
• Countries should have access to available
international literature on weeds and also to
internet related web pages in order to get the
required information for the assessment.
• Weed risk assessment will for sure improve
the work of plant quarantine bodies in the
country, making possible to focus on really
exotic dangerous weeds.
Importance of WRA to avoid new
problems of invasive weeds
• Many of invasive plants have been introduced in
several countries without any regulation.
• Mesquite or Prosopis is an example, introduced in
several countries to help reduce the problems of
drought, where years later it became a terrible weed.
• There are many other examples. Prevention is the
first way to combat weed spread, and WRA
procedures are excellent tools to this end.
Thank you