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This Weed Risk Management Assessment uses a series of questions to arrive at scores for weed risk and feasibility of coordinated control for this weed, and displays the necessary management actions derived from these scores.

This information is then used to make decisions about the introduction, prioritisation and status of this weed in New South Wales.

Weed (Scientific name) Phyla canescens
Weed (Common name) Lippia
Region All of NSW
Management area Grazing areas
Landuse 2.1 Grazing natural vegetation 
Assumptions Lippia (Verbenaceae). Grazing areas across all of NSW are predominantly unimproved pastures.Standard weed management is limited. In the east pasture management for competitive pastures and varying stocking rates are most common. Fertiliser application is common in the east in some places.  Herbicide application may be used as well as cultivation and resowing of areas. Limited use of broad-scale herbicide applications and cultivation in the west. Density in land use: high.
Weed Risk
Invasiveness Score      Total Answers Source and comments
Q1. What is the ability of the weed to establish amongst existing plants? 1.0 Seedlings establish after moderate disturbance P. Welchman personal observations.
Q2. What is the weed's tolerance to average weed management practices in the land use? 3.0 95% + weeds survive common management Personal observations.
Q3. What is the reproductive ability of the weed in the land use? 3.0   Leigh and Walton (2004). 
(a) Time to seeding 2.0 1 year or less
(b) Annual seed production 1.0 Low
(c) Vegetative reproduction 2.0 Frequent
Q4. How likely is long-distance dispersal (>100m) by natural means? 1.0   Leigh and Walton (2004). 
(a) Flying animals 0.0 Unlikely
(b) Other wild animals 0.0 Unlikely
(c) Water 2.0 Common
(d) Wind 0.0 Unlikely
Q5. How likely is long-distance dispersal (>100 m) by human means? 2.0   Leigh and Walton (2004). 
(a) Deliberate spread by people 1.0 Occasional
(b) Accidentally by people and vehicles 1.0 Occasional
(c) Contaminated produce 1.0 Occasional
(d) Domestic/farm animals 1.0 Occasional
Total 6.7   
Impacts Score      Total   
Q1. Does the weed reduce the establishment of desired plants? 3.0 > 50% reduction Leigh and Walton (2004). 
Q2. Does the weed reduce the yield or amount of desired vegetation? 4.0 > 50% reduction Leigh and Walton (2004). 
Q3. Does the weed reduce the quality of products, diversity or services available from the land use? 2.0 Medium Leigh and Walton (2004) and Coutts-Smith and Downey (2006) - threatens Coolibah and box woodland - an EEC.
Q4. What is the weed's potential to restrict the physical movement of people, animals, vehicles, machinery and/or water? 0.0 None Leigh and Walton (2004). 
Q5. What is the weed's potential to negatively affect the health of animals and/or people? 1.0 Low Leigh and Walton (2004). 
Q6. Does the weed have major positive or negative effects on environmental health? 2.0   a., b., e. and f. Leigh and Walton (2004). C. and d, 'Do not know' .
(a) food/shelter 0.0 Minor or no effect
(b) fire regime 0.0 Minor or no effect
(c) altered nutrient levels ? Do not know
(d) soil salinity ? Do not know
(e) soil stability 1.0 Major negative effect
(f) soil water table 1.0 Major negative effect
Total 6.3   
Potential distribution    
Q1. Within the geographic area being considered, what is the percentage area of land use that is suitable for the weed?  8.0 60-80% of land use Estimate.
Comparative weed risk score 337   
Weed risk category Very high   
Feasibility of coordinated control
Control costs Score      Total   
Q1. How detectable is the weed?  2   Leigh and Walton (2004).
(a) Distinguishing features 0 always distinct
(b) Period of year shoot growth visible 0 > 8 months
(c) Height at maturity 2 <0.5 m
(d) Pre-reproductive height in relation to other vegetation 2 below canopy
Q2. What is the general accessibility of known infestations at the optimum time of treatment? 0 high Leigh and Walton (2004).
Q3. How expensive is management of the weed in the first year of targeted control? 2   Leigh and Walton (2004). 
(a) Chemical costs/ha 1 low (< $100/ha)
(b) Labour costs/ha 2 medium ($100-$249/ha)
(c) Equipment costs 1 low
Q4. What is the likely level of participation from landholders/volunteers within the land use at risk? 2.0 low Leigh and Walton (2004).
Total 5.0   
Persistence Score      Total   
Q1. How effective are targeted management treatments applied to infestations of the weed? 3 low Leigh and Walton (2004).
Q2. What is the minimum time period for reproduction of sexual or vegetative propagules? 3 < 6 months Leigh and Walton (2004).
Q3. What is the maximum longevity of sexual or vegetative propagules? 1 2-5 years L. Tanner personal communication.
Q4. How likely are new propagules to continue to arrive at control sites, or to start new infestations? 2.0   Leigh and Walton (2004). 
(a) Long-distance (>100m) dispersal by natural means 2 frequent
(b) Long-distance (>100m) dispersal by human means  1 occasional
Total 8.2   
Current distribution    
Q1. What percentage area of the land use in the geographical area is currently infested by the weed? 4.0 20-40% of land use Estimate.
Q2. What is the number of infestations, and weed distribution within the geographic area being considered?  2.0 widespread Personal observations.
Total 5.0   
Comparative feasibility of coordinated control score 205
Feasibility of coordinated control category Negligible
Management priority category Manage weed
Calculation of overall uncertainty score 2%
Positive Impacts Supposedly reduced fire risk in forestry but no evidence found in NSW. Used as a drought tolerant broad leaf lawn. Use in honey production by apiarists? Does it have any grazing value?
References/Other comments
Coutts-Smith, A. J. and Downey, P. O. (2006). The impact of weeds on threatened biodiversity in NSW. Technical series no.11. CRC for Australian Weed Management Systems, Adelaide. 100 pp.
Leigh, C. and Walton, C. S. (2004).  Lippia (Phyla canescens) in Queensland. Queensland Department of Natural Resources and Mines, Brisbane. 34 pp.

Assessment by Dr Stephen Johnson, Weed ecologist, I&I NSW, 17 May 2010.

This assessment does not include riparian areas that are not grazed.