Gundagai

Pest Plants

What the results tell us for Gundagai

Gundagai Shire Council listed ten priority pest plant species within their shire during the reporting period. All of the priority pest plants have the potential to adversely impact on primary productivity, with four being potentially harmful to stock and one able to contaminate wool. Some increase in infestations was reported for only two species.

photo of Silverleaf Nightshade, credit: Les Tanner, http://www.northwestweeds.nsw.gov.au/weed_photos.htm

Over the current reporting period, Council carried out weed control activities for all ten priority weeds. Eight species were reported to have decreased or remain stable over that time. The NSW Department of Environment and Conservation also undertook control activities for five weed species in the two nature reserves within the shire. Although one priority weed species was reported to occur in state forests, no detailed information was available about the severity of infestations or whether control measures were undertaken.

This is the first reporting period for which Gundagai Shire has been included in the Australian Capital Region State of the Environment Report. As such, no comparative data were available for comparing trends over the previous reporting period.

Pest plant infestations

Ten priority pest plant species were identified in Gundagai Shire for the current reporting period: Black Willow (Salix nigra), Blackberry (Rubus fruticosus agg. spp), Coolatai Grass (Hyparrhenia hirta), Horehound (Marrubium vulgare), Illyrian Thistle (Onopordom illyricum), Johnson Grass (Sorghum halepense), Serrated Tussock (Nassella trichotoma), Silverleaf Nightshade (Solanum elaeagnifolium), St John's Wort (Hypericum perforatum) and Sweet Briar (Rosa rubiginosa). Coolatai Grass will be listed on Council's noxious weeds list by the end of the next reporting period.

photo of Coolatai Grass, credit: Les Tanner, http://www.northwestweeds.nsw.gov.au/weed_photos.htm

All of the priority pest plants have the potential to adversely impact on primary productivity. St John's Wort, Johnson Grass, Serrated Tussock and Silverleaf Nightshade are potentially harmful to stock, and Horehound is able to contaminate wool.

The location, approximate area and density of infestation of the priority pest plant species in the shire are summarised in Table 1. Illyrian Thistle and Blackberry were the only species reported to have shown some increase in infestations during the reporting period.

Table 1. Priority pest plant species in Gundagai Shire, July 2000 to June 2004
Pest plant species	Location and area of infestations *
Black Willow (Salix nigra)	Up and downstream along the Murrumbidgee river. Infestations are at the following densities: High density infestation—2 hectares Scattered plants—1 hectare
Blackberry (Rubus fruticosus agg. spp)	State Forests within the Adjungbilly area. Scattered plants along Council roads. Infestations are at the following densities: High density—6,500 hectares
Coolatai Grass (Hyparrhenia hirta)	Along streets in Gundagai township. Infestations are at the following densities: Scattered plants—2 hectares
Horehound (Marrubium vulgare)	Jones Creek, Burra area. Infestations are at the following densities: Medium density infestation—30 hectares
Illyrian Thistle (Onopordom illyricum)	Along Muttama, Caulderwood, Darbalara, Nangus, Tarrabandra, Mingay and Coolac Roads. Infestations are at the following densities: High density infestation—100 hectares Scattered plants—50 hectares
Johnson Grass (Sorghum halepense)	Nangus, river flats upstream on the Murrumbidgee River from Gundagai. Tumut, O'Briens, Nangus, Burra, Mundarlo and Edwardstown Roads and Pope Street. Infestations are at the following densities: Low density infestation—10 hectares
Serrated Tussock (Nassella trichotoma)	Mount Reno, Burr and Nangus areas. Infestations are at the following densities: High density infestation—7 hectares
Silverleaf Nightshade (Solanum elaeagnifolium)	Nangus area on the Bethungra Road. Infestations are at the following densities: High density infestation—100 hectares Scattered plants—1.5 hectares
St John's Wort (Hypericum perforatum)	Adjungbilly, Gocup, Snowy Mountains Highway area. Infestations are at the following densities: High density infestation—120–200 hectares Low density infestation—10 hectares Scattered plants—50 hectares
Sweet Briar (Rosa rubiginosa)	Adjungbilly Creek area, Kangaroo Mountain. Infestations are at the following densities: High density infestation—150 hectares

* Note: High density infestation (80–100% cover); Medium density infestation (50–79% cover); Low density infestation (10–49% cover); Scattered plants (< 10% cover); Source: Gundagai Shire Council

Approximately 76% of Ellerslie Nature Reserve and 2% of Ulandra Nature Reserve occur within Gundagai Shire. Nine major weed species were recorded within them by the NSW Department of Environment and Conservation (DEC—formerly NSW National Parks and Wildlife Service) in the 2002–04 financial years (Table 2). Weed species affected a much greater area of Ulandra Nature Reserve than Ellerslie Nature Reserve, with Paterson's Curse and St John's Wort affecting 80% of the former reserve (see Table 2).

Table 2. Pest plants in conservation reserves within Gundagai Shire, July 2002 to June 2004
Pest plants	Location	Proportion of reserve affected #	Year
Blackberry	Ellerslie Nature Reserve	10%	2002–04
Blackberry	Ulandra Nature Reserve	50%	2002–04
Noogoora Burr	Ulandra Nature Reserve	unknown	2002–03
Pasture grasses	Ulandra Nature Reserve	5%	2003–04
Paterson's Curse (Echium platagineum)	Ulandra Nature Reserve	80%	2002–04
Paterson's Curse (Echium platagineum)	Ellerslie Nature Reserve	5%	2002–04
St John's Wort	Ellerslie Nature Reserve	5%	2002–04
St John's Wort	Ulandra Nature Reserve	80%	2002–04
Sweet Briar	Ulandra Nature Reserve	20%	2002–04
Thistles	Ellerslie Nature Reserve	1%	2003–04
Thistles	Ulandra Nature Reserve	5%	2003–04
Tree of Heaven (Ailanthus altissima)	Ellerslie Nature Reserve	30%	2002–04
Willows	Ellerslie Nature Reserve	1%	2002–04

# The percentage of reserve covered is for the 2003–04 financial year; Source: NSW Department of Environment and Conservation

The entire areas of Buccleuch and Bungongo state forests and 10% of Red Hill State Forest occur within Gundagai Shire. No detailed information was available regarding the presence of pest plant species within these areas.

Pest plants as threatening processes

A final determination to list 'Invasion of native plant communities by exotic perennial grasses' as a key threatening process under the Threatened Species Conservation Act 1995 was made by the NSW Scientific Committee during the current reporting period. The exotic perennial species included Serrated Tussock and Coolatai Grass, both of which are of concern within the shire. The impacts of exotic perennial grasses as outlined in the final determination of the Scientific Committee include (DEC 2004):

competition with or displacement of native species
local and regional declines in many native plant species and communities.

Pest plant control activities

NSW Government agencies

In the 2003–04 financial year, DEC undertook control programs for Patterson's Curse, St John's Wort and Blackberry within Ulandra Nature Reserve and Willow, Blackberry and Tree of Heaven within Ellerslie Nature Reserve. No information regarding expenditure or effectiveness of control measures was available.

No information was available on control programs for pest plant species within Buccleuch, Bungongo or Red Hill state forests.

Gundagai Shire Council

Regional Weed Management plans for the Riverina Region developed during the reporting period were relevant to the following five pest plant species in Gundagai Shire:

Black Willow (EWRNWAG, 2002a)
Johnson Grass (EWRNWAG, 2000a)
Scotch/Illyrian Thistle (EWRNWAG, 2000b)
Serrated Tussock (EWRNWAG, 2002b)
St John's Wort (EWRNWAG, 2002c).

Two Regional Weed Management plans that came into force on 1st July 2004 were relevant to the following pest plant species in the shire:

Blackberry (EWRNWAG, 2004a)
Silverleaf Nightshade (EWRNWAG, 2004b).

These regional plans enable a coordinated approach to pest plant control. All plans include a strong focus on raising Council, State Agency and community awareness of these weeds with respect to their identification, potential impacts and control options.

The objectives of control programs for major weeds within Gundagai Shire are outlined in Table 3. Control programs there largely focussed on controlling infestations along Council roads and on private property. Weed control methods for all priority pest plants predominantly involved the use of herbicide. Biological control methods were also used in conjunction with other methods to control St John's Wort, Horehound and Illyrian Thistle.

Table 3. Major objectives of control programs for some priority weeds within Gundagai Shire
Pest plants	Objectives of control program
Black Willow	remove major seed source by 2007 remove all core infestations along Adelong Creek by 2007 remove marginal infestation along the Murrumbidgee River at Gundagai by 2007 locate rare and isolated infestations and new infestations—these are to be treated within 1 year of discovery
Blackberry	limit spread into uninfested areas identify and remove all isolated infestations by 2005 and rehabilitate these areas identify and implement a minimum of 20 projects (in the Riverina Highlands Region) within light or medium infested areas and target on-ground control to removing all plants and rehabilitating these areas minimise spread from heavily infested areas support biological control programs in heavily infested areas particularly in inaccessible areas educate and involve the community in Blackberry management
Johnson Grass	prevent spread by removing new infestations prior to seed set reduce rare and isolated infestations by 45% by 2005 reduce marginal infestations to rare and isolated by 2005 contain existing core infestations
Serrated Tussock	prevent spread by removing new infestations prior to seed set reduce existing infestations by 30% by 2007
Silverleaf Nightshade	minimise spread by controlling new infestations prior to seed set prevent spread of rare and isolated infestations contain and prevent spread of marginal infestations contain core infestations limit spread into uninfested areas
St John's Wort	limit increase to existing core areas prevent spread from core areas reduce marginal infestations by 20% by 2007 reduce rare and isolated infestations by 50% by 2007

Source: EWRNWAG (2000–2004)

Expenditure on and effectiveness of pest plant control

Expenditure on weed control for selected priority pest plant species within Gundagai Shire over the reporting period, and outcomes of the control programs, are summarised in Table 4. Council received funding from the Department of Primary Industries (DPI—formerly NSW Agriculture) for six of the weed species.

The majority of funding for weed control within the shire was expended on Blackberry, Serrated Tussock, Illyrian Thistle and St John's Wort. Control activities resulted in reductions of St John's Wort, Blackberry and Serrated Tussock. However one infestation of Illyrian Thistle increased and increasing numbers of scattered Illyrian Thistle plants were recorded, despite the control measures. These changes can largely be attributed to wind and bird dispersal of the thistle's seed.

All other priority weed infestations within the shire were reported either to have decreased or remained stable during the current reporting period. Black Willow had the greatest reduction in area due to control works, with all existing plants in the shire poisoned. However, due to the existing Black Willow soil seed bank, it is expected that on-going monitoring will be required to locate and eradicate any seedlings which may appear.

Blackberry reportedly decreased in all areas of the shire except areas of State Forest. Infestations of St John's Wort along roadsides and on private property also decreased due to the introduction of biological control. The area of infestation of Johnson Grass was reported to have decreased along roadsides, but remain stable on private property due to landuse practices, such as the ploughing of paddocks, which only break up the plant clumps and allow the plants to regrow.

Table 4. Priority pest plant control undertaken by Council in Gundagai Shire, July 2000 to June 2004
Annual expenditure on controlling pest plant species			Outcome: Change in abundance or spread from levels in 2001	Total Area treated (ha)
Year	Amount	Source of funding#	Outcome: Change in abundance or spread from levels in 2001	Total Area treated (ha)
Black Willow (Salix nigra)
2000–01	$600	Council & DPI	Significantly reduced	Unknown
2001–02	$600
2002–03	$600
2003–04	$600
Blackberry (Rubus fruticosus agg.)
2000–01	$5,000	Council & DPI	Decreased in all of shire except on State Forest lands	Unknown
2001–02	$4,450
2002–03	$4,200
2003–04	$0
Coolatai Grass (Hyparrhenia hirta)
2000–01	No funding		Decreased	Unknown
2001–02
2002–03
2003–04
Horehound (Marrubium vulgare)
2000–01	No funding		Decreased along roadsides	Unknown
2001–02
2002–03
2003–04
Illyrian Thistle (Onopordum spp)
2000–01	$7,400	Council	One infestation has increased; increasing numbers of scattered plants	Unknown
2001–02	$0
2002–03	$7,400
2003–04	$0
Johnson Grass (Sorghum halepense)
2000–01	$1,650	Council & DPI	Decreased along all roads Private property infestations are stable	Unknown
2001–02	$1,500
2002–03	$1,350
2003–04	$0
Serrated Tussock (Nassella trichotoma)
2000–01	$1,500	Council & DPI	Decreased but ongoing monitoring required	Unknown
2001–02	$1,500
2002–03	$1,800
2003–04	$1,800
Silverleaf Nightshade (Solanum elaeagnifolium)
2000–01	$800	Council & DPI	Stable—infestations only occur on one property	Unknown
2001–02	$690
2002–03	$580
2003–04	$0
St John's Wort (Hypericum perforatum)
2000–01	$0	Council & DPI	Decreased	Unknown
2001–02	$0
2002–03	$3,000
2003–04	$3,000
Sweet Briar (Rosa rubiginosa)
2000–01	No funding		Decreased	Unknown
2001–02
2002–03
2003–04

Source: Gundagai Shire Council
# Where the source of funding is shown as Council and DPI the figures quoted are grant monies from DPI only and do not include the Council contribution.

About the data

Data were provided by Gundagai Shire Council. Data collected for the Ecologically Sustainable Forest Management Program for the 2003–04 financial year were provided by DEC South West Slopes region. Regional Weed Management Plans were provided by the Eastern Riverina Noxious Weeds Advisory Group.

The photographs of Coolatai Grass seed head and plant and Silverleaf Nightshade flower were both taken by Les Tanner. See http://www.northwestweeds.nsw.gov.au/weed_photos.htm for more information.

References

DEC—see Department of Environment and Conservation (NSW)

Department of Environment and Conservation (NSW) (2004) NSW Scientific Committee—Final Determination, Invasion of Native Plant Communities by Exotic Perennial Grasses—Key Threatening Process Declaration, NSW Department of Environment and Conservation, viewed 3 February 2005, http://www.nationalparks.nsw.gov.au/npws.nsf/ Content/Invasion+of+native+plant+communities+by+exotic+perennial+grasses+key+ threatening+process+declaration

Eastern and Western Riverina Noxious Weeds Advisory Groups (2000a) Riverina Johnson Grass Management Plan No. 746—Regional Weed Management Plan 2000—2005, Eastern and Western Riverina Noxious Weeds Advisory Groups.

Eastern and Western Riverina Noxious Weeds Advisory Groups (2000b) Riverina Scotch / Illyrium Thistle Management Plan—Regional Weed Management Plan 2000—2005, Eastern and Western Riverina Noxious Weeds Advisory Groups.

Eastern and Western Riverina Noxious Weeds Advisory Groups (2002a) Riverina Black Willow Management Plan—Regional Weed Management Plan 2002—2007, Eastern and Western Riverina Noxious Weeds Advisory Groups.

Eastern and Western Riverina Noxious Weeds Advisory Groups (2002b) Riverina Serrated Tussock Management Plan—Regional Weed Management Plan 2002—2007, Eastern and Western Riverina Noxious Weeds Advisory Groups.

Eastern and Western Riverina Noxious Weeds Advisory Groups (2002c) Riverina St John's Wort Management Plan—Regional Weed Management Plan 2002—2007, Eastern and Western Riverina Noxious Weeds Advisory Groups.

Eastern and Western Riverina Noxious Weeds Advisory Groups (2004a) Riverina Highlands Blackberry Management Plan—Regional Weed Management Plan 2004—2009, Eastern and Western Riverina Noxious Weeds Advisory Groups.

Eastern and Western Riverina Noxious Weeds Advisory Groups (2004b) Riverina Silverleaf Nightshade Management Plan No. 704—Regional Weed Management Plan 2004—2009, Eastern and Western Riverina Noxious Weeds Advisory Groups.

EWRNWAG—see Eastern and Western Riverina Noxious Weeds Advisory Groups

2004 Report