All in Weeds

Ecological, economic and social considerations of spray control for Hymenachne

Mon, 18 Aug 2008 06:21:26 +0000

IDs and People

Program:

Defeating the Weed Menace R&D Program

Program Theme:

Quantifying the impacts of weeds on sustainability and the environment and the relative benefits and costs

Research Type:

Research Project

Legacy (KMS) Project ID:

UCQ4

Host Organisation:

Central Queensland University

Researchers:

B.Miles

J.Rolfe

L.Duivenvoorden

W.Houston

Subjects

Subjects:

Data and Information

Weeds

Keywords:

Weeds

Project Information

Summary:

Hymenachne, a Weed of National Significance (WONs), is an aquatic plant invading northern Australia’s wetlands and waterways. The proliferation of this weed is associated with serious ecological losses and there are substantial costs associated with its control. Hymenachne also deserves special attention given the nexus regarding its beneficial use as a ponded pasture species for livestock production and drought management, and the disadvantages associated with its spread and ecological impact. A key challenge in the management of this weed is to understand the best ways to approach Hymenachne control, whilst satisfying environmental, social and economic concerns.

This study used a triple bottom line approach to improving the understanding of the issues facing Hymenachne control. This involved the integration of the social, economic and ecological studies and ecological surveys conducted in conjunction with a sample spray regime.

Outcomes:

Key findings were the need for a coordinated and inclusive approach to Hymenachne control across all stakeholders and landholders, with suitable incentives being made available and responsibility taken for control by each of the Government, Councils and the community. With respect to chemical control spraying, there was little evidence that this causes long-term, significantly negative effects on freshwater systems with respect to water quality, pesticides residuals, and biota (macroinvertebrates, fish and semi-aquatic invertebrates). This contrasts with the known adverse ecological effects of dense Hymenachne cover demonstrated in earlier studies, thus suggesting that control sprays should be employed to reduce existing infestations and prevent new outbreaks.

Current Activities

Status:

Complete

Background

Project Background:

Hymenachne, a Weed of National Significance, is an aquatic pest plant that is invading northern Australian wetlands and waterways. Its proliferation is associated with serious ecological issues and there are substantial costs associated with its control. However, Hymenachne is also valued by some livestock producers as a ponded pasture important in drought management.

A significant challenge for the control of Hymenachne is to balance the economic, social and environmental costs and benefits of its use and management.

Aims:

Project objectives:

1. A detailed review of literature will report on issues including, but not limited to, the current spread of Hymenachne, existing methods for control, available data on ecological consequences of spray regimes and the socio-economic impacts of the weed and different control measures.

2. The ecological component of the study will address the following research questions:

(a) What are the adverse ecological impacts associated with chemical spray regimes (e.g., decline in water quality, changes to aquatic habitats, loss in vertebrate & invertebrate biodiversity)?

(b) What is the extent of system recovery in the short term, following spray and/or successful hymenachne control (possibly including recolonisation by native vegetation)?

3. The key research questions for the economics component relate to the knowledge, barriers and incentives that will generate participation in control strategies:

Quantifying the economic costs of control and the level of incentives needed to generate effective participation
on-farm economic losses due to lost production where Hymenachne is removed from ponded pastures
costs of control measures
types and levels of incentives needed to encourage on-farm control activities,
the structure of incentive mechanisms needed to generate sufficient participation by landholders at a landscape scale.

4. The investigation of broader social issues regarding Hymenachne will include questions such as:

What is the current level of awareness & perceptions of the Hymenachne problem in central Queensland by landholders?
What is the extent of willingness to participate in control programs?
What barriers, catalysts and enablers influence landholder adoption of, and/or cooperation with, Hymenachne control regimes?
An analysis of conflicts of interest existing in regards to Hymenachne as (a) a ponded pasture grass used for livestock production and (b) an ecologically destructive weed of national significance
Investigations of strategies that could be put in place to foster greater awareness of the weed problem, cooperation across stakeholder groups and a wider adoption of control

Land use effects on soil nutrient enrichment: Risks for weed invasion

Mon, 18 Aug 2008 02:01:58 +0000

IDs and People

Program:

Defeating the Weed Menace R&D Program

Program Theme:

Land use change impacts on weed incursion

Research Type:

Research Project

Legacy (KMS) Project ID:

CEN9

Host Organisation:

CSIRO Entomology

Researchers:

Elizabeth Lindsay

Dr Saul Cunningham

Subjects

Subjects:

Data and Information

Landscape Management

Weeds

Keywords:

Soil

Weeds

Vegetation

weed

nutrient enrichment

bungendore

murrumbateman

boorowa

young

Project Information

Summary:

This project examined various soil and vegetation properties of remnant eucalypt grassy woodlands under different livestock grazing regimes within agricultural landscapes on the southern tablelands and south west slopes of N.S.W. All woodlands contained a minimum of two exotic plant species and there was up to 94% exotic plant cover in the understorey.

The most common invasive exotic plants were annual exotic grasses, most of which were introduced in the past to surrounding areas as pasture grasses. The top soil was generally enriched in various forms of nitrogen and phosphorous compared to published information on woodlands with a low disturbance history. There was no difference in the soil nutrient status between sites with livestock grazing excluded and those with low to high intensity grazing. This indicates that soil nutrient levels within woodlands will take a long time to decline to original levels once a major source, livestock, has been removed.

Exotic plant cover and diversity in the understorey increased as soil nutrient concentrations increased, whereas native plant diversity decreased as soil nutrient levels increased. Exotic plant cover increased as native plant cover decreased. Managing for a low soil nutrient status and high native plant understorey diversity and cover could assist in controlling exotic plants in woodlands.

A rotational grazing scheme rather than a setstock grazing regime would also help to maintain the native plant understorey. Land use intensity appears to alter the soil seed bank, soil properties and the weed community in woodland remnants. The land use history of a site appears just as important as the current property or landscape use; however this information is not always available.

The understorey of remnants in a grazing landscape are likely to be easier to restore and protect than those in the higher intensity cropping and grazing landscapes. When restoring the woodland understorey through native grass seedbaddition, there will be greater success if seeds are sown in areas of low soil ammonium and close to mature eucalypt trees. Weed invasion and nutrient enrichment are two major problems affecting the longevity of remnant grassy woodlands in agricultural landscapes. Minimising nutrient inputs and exotic grass dominance will assist in maintaining small remnants in highly modified landscapes.

Outcomes:

Results show that though remnant woodlands have been affected by agricultural practices, they are remarkably resilient. Minimising grazing pressure can improve the functioning of invertebrate communities and ecosystem processes within remnant woodlands. Livestock exclusion won’t improve all sites, and for some, additional remediation work will be required. With careful management, remnant vegetation can still be part of the production system within a livestock grazing property, with fencing making strategic grazing easier. Woodland vegetation needs to be rested from grazing and stock camping in woodlands should be minimised to stop further nutrient enrichment.

Current Activities

Status:

Complete

Background

Project Background:

Most of the eucalypt woodlands in south eastern Australia exist as remnants in highly modified agricultural landscapes, commonly on private land (McIntyre et al., 2002). In order to preserve the remaining woodlands we need to better understand the disturbances they face (e.g. land clearing, edge effects, livestock grazing, nutrient enrichment, weed invasion) and how to balance the conservation and production needs of these landscapes.

Aims:

This study aimed to understand the impacts of productive land use (livestock grazing and cropping) on soil nutrient enrichment and the understorey vegetation in small remnant grassy woodlands in agricultural landscapes. Sites were on the southern tablelands and south west slopes of N.S.W near the towns of Bungendore, Murrumbateman, Boorowa and Young (Appendix Fig. A1).

The main objectives of this project were to determine;

what exotic plants are common in woodlands?
the relationship between weed diversity and abundance and soil nutrient levels,
the impacts of weed invasion and nutrient enrichment on the understorey vegetation,
if there are native plant seeds in the soil seed bank that are not present as adults, and if there are
native plant species that are rare as adults but with a large seed reserve in the soil
how nutrient enrichment, weed invasion and the seed bank change with the current grazing regime
and land use intensity
what is inhibiting native grass germination and establishment in exotic grass dominated woodlands?

Enhancing Noogoora Burr biocontrol in northern Australia

Mon, 18 Aug 2008 01:39:37 +0000

IDs and People

Program:

Defeating the Weed Menace R&D Program

Program Theme:

Identifying biocontrol agents for priority weed species

Research Type:

Research Project

Legacy (KMS) Project ID:

CEN7

Host Organisation:

CSIRO Entomology

Researchers:

Dr Louise Morin

Subjects

Subjects:

Data and Information

Threats and Pests

Weeds

Keywords:

Weeds

weed

Noogoora burr

biocontrol

Project Information

Summary:

This project investigated ways to improve the biollgical control of the highly invasive weed Noogoora Burr (Xanthium occidentale). The project was designed to assemble the necessary information to support an application to release additional strains of the Noogoora Burr rust fungus to enhance the impact of biological control in northern Australia. The introduction of additional exotic rust strains better adapted to tropical conditions is being investigated as a means of controlling Noogoora Burr in tropical areas.

Outcomes:

Following field surveys carried out in tropical America, rust-infected material from 12 sites in Dominican Republic and Mexico was imported into the containment facility. No infection of Australian Noogoora burr accessions was obtained with the imported rust material. In contrast, plants inoculated with two Australian rust strains developed severe symptoms; confirming that experimental conditions were suitable for infection. As a result, it was not possible to establish cultures of exotic strains and perform host-specificity tests.

Microscopic examination of leaves inoculated with exotic rust-infected material revealed typical plant resistance responses. Xanthium specimens collected in Dominican Republic and Mexico were found to be morphologically and genetically different to Australian Noogoora burr accessions and other Xanthium spp. These genetic differences may explain why no infection occurred on Australian Noogoora burr inoculated with rust-infected material from tropical America.

A diagnostic microsatellite marker to differentiate between exotic and Australian rust strains was successfully developed to provide a tool for monitoring strain establishment after release. Baseline data on Noogoora burr populations and prevalence of biocontrol agents were collected at sites on three river systems in the Northern Territory and northern Western Australia. This data will be essential to assess the impact of additional strains of P. xanthii, should any be released in the future in Australia.

Current Activities

Status:

Complete

Background

Project Background:

Noogoora burr (Xanthium occidentale; ranked 28th during the WoNS process and an approved target for biocontrol) forms monocultures across the northern regions of Australia. The exotic rust fungus, Puccinia xanthii, illegally or accidentally introduced in the mid-1970s to Australia, has been highly effective in controlling Noogoora Burr in south-eastern Queensland, but has failed to have a major impact in tropical northern Australia (Morin et al., 1996).

Aims:

The project objectives were:

collect, characterise and test host-specificity of exotic strains of Puccinia xanthii that are better adapted to the tropical climate, and
gather baseline data of Noogoora burr populations in northern Australia.

Location

State & NRM Region:

Western Australia

Northern Territory

Boneseed Rust: A highly promising candidate for biological control

Mon, 18 Aug 2008 01:28:35 +0000

IDs and People

Program:

Defeating the Weed Menace R&D Program

Program Theme:

Identifying biocontrol agents for priority weed species

Research Type:

Research Project

Legacy (KMS) Project ID:

CEN24

Host Organisation:

CSIRO Entomology

Researchers:

Dr Louise Morin

Subjects

Subjects:

Data and Information

Weeds

Keywords:

Weeds

weed

biocontrol

boneseed rust

Project Information

Summary:

This project investigated the use of Endophyllum osteospermi (a systemic rust fungus) in the biological control of boneseed (Chrysanthemoides monilifera ssp. monilifera). This systemic South African rust fungus has been found to reduce growth and the reproduction of plants by causing extensive deformation of infected branches (witches’ broom).

Boneseed is a Weed of National Significance, which occurs mainly in Victoria, South Australia and Tasmania.

Outcomes:

This project has generated new approaches to the establishment and detection of boneseed rust that will play important roles in future development of biological control agents for boneseed. Through the adaptive approach to the research and appropriate applications to AQIS, the Principal investigator has also achieved innovative new approaches to tge use of traditional 3-tiered host specifity esting for biocontrol agents. Each of these new aspects of knowledge may have applications beyond the specific case under study - rust fungus control of boneseed.

Current Activities

Status:

Complete

Background

Project Background:

This project is building on research conducted in South Africa in the mid-1990s.

Aims:

This project aims to complete the host-specificity testing phase of the boneseed rust to provide the necessary data to finalise the risk assessment for this rust and build a strong case to support its release in Australia. This will be achieved by:

Carrying out inoculations of the six non-target plant species on which penetration occurred in initial host-specificity tests, and microscopically examining samples taken 4 weeks after inoculation to determine if the rust has successfully colonised plant tissue. (Modified objective proposed to L&W Australia in March 2007 and accepted on 7 June 2007)
Preparing and submitting an application to release the rust to the regulatory authorities.
Developing a molecular-based tool to enable detection of the rust in symptomless plants after release since it can takes up to 2-3 years for visible disease symptoms to develop.
Negotiating with AQIS to determine an acceptable approach to release the rust from the quarantine facility.

Location

State & NRM Region:

South Australia

Victoria

Tasmania

Biological control and ecology of Alligator Weed

Mon, 18 Aug 2008 00:55:51 +0000

IDs and People

Program:

Defeating the Weed Menace R&D Program

Program Theme:

Identifying biocontrol agents for priority weed species

Research Type:

Research Project

Legacy (KMS) Project ID:

CEN11

Host Organisation:

CSIRO Entomology

Researchers:

Dr Shon Schooler

Subjects

Subjects:

Mapping and Modelling

Weeds

Keywords:

Weeds

weed

biocontrol

alligator grass

Project Information

Summary:

This project investigated the potential use of biological control agents to assist
in the management of alligator weed in Australia. This was achieved through:

testing the host specificity of two herbivorous insects for potential use
as biological control agents,
completing ecological studies to better understand alligator weed in order
to develop and promote more effective methods of control.

Outcomes:

The study found that using low concentrations of selective herbicides will increase the competitive ability of grass species and lead to a reduction in alligator weed over time. This replaces prior practices that used broad spectrum herbicides (glyposphate) to manage this weed.

The study identified tip galling fly (Clinodiplosis alternantherae) as a potential biological control agent, but unfortunately it can complete its life cycle on at least two native plant species, and so is not safe to release in Australia. The testing of two other biological control agents, a leaf mining fly (Ophimyia morelli), and a beetle (Systena nitenula) were not able to be completed due to difficulty in exporting the organisms out of Argentina. A fungus, Uredo pacensis, from Bolivia, has been identified as an additional potential biological control agent. More research is required to see if this fungus will attack the varieties of alligator weed found in Australia.

A preliminary genetic analysis has found that there were probably three separate introductions of alligator weed to Australia. Australian populations have been found to be genetically similar to populations in Buenos Aires, Salta and Santa Fe/Chaco.

Current Activities

Status:

Complete

Background

Project Background:

This project follows on from a NHT-funded project (2003-06).

Aims:

This project continues the host testing of insects for the biological control of alligator weed and continues ecological studies to underpin development of better management strategies for the weed in Australia. We currently have a ranked list of potential agents and will continue the testing, apply for permits to release, and potentially release host specific insects within the timeframe of this project. Ecological studies will include comparing habitats of the native and introduced ranges to identify the most promising biological control agents and studying factors that allow alligator weed to outcompete desired vegetation in Australia.

Location

State & NRM Region:

National

Managing weeds under future scenarios for environmental flows in the Murray River

Sun, 17 Aug 2008 22:52:56 +0000

IDs and People

Program:

Defeating the Weed Menace R&D Program

Program Theme:

Early Detection, Survey and Eradication of Potential Weed Species

Research Type:

Research Project

Legacy (KMS) Project ID:

CEN6

Host Organisation:

CSIRO Entomology

Researchers:

Dr Matthew Colloff

Subjects

Subjects:

Monitoring and Assessment

Weeds

Environmental Flows

Keywords:

Weeds

weed

murray river

Project Information

Summary:

This project aims to determine site indicators that will clarify risk with respect to weed invasion, and how this risk is affected by patterns of flooding. This will assist in reducing the spread of weeds in riparian and floodplain environments and in restoring native vegetation in systems that are degraded.

Outcomes:

Management implications of results derived from small spatial scales indicate improving environmental water allocations is predicted to result in a reduction in exotic weeds, since fewer exotics occur in functional groups that require flooded conditions to germinate.

The early involvement of the traditional owners of the study area has had an additional positive impact on this project.

Current Activities

Status:

Complete

Background

Project Background:

Many exotic weeds have colonized floodplain and riparian environments in Australia, including blackberry (Rubus spp.), willows (Salix spp.) bridal creeper (Asparagus asparagoides), cabomba (Cabomba caroliniana) and Lippia (Phyla canescens)). These weeds can have substantial negative impacts on the biodiversity values of riparian environments, and can spread away from the river banks to invade otherwise productive agricultural land. Flooding promotes growth and reproduction of many riparian plants, activates the sexual and asexual propagules of aquatic and semi-aquatic species and eliminates flood-intolerant species that colonize the floodplain during dry periods.

Riparian and floodplain environments have been subject to many stressors due to land use changes in the past, but it is known that more significant changes will occur in the next decade. State and federal governments are co-ordinating to increase the amount of water released in Australia’s largest river in the form of environmental flows. The primary goal of this program is to restore ecosystem health to the Murray river. At the same time must minimise negative consequences for productive land use. As such, a great challenge must be faced, how to release water in a manner that will maximise environmental benefits? For this study, the question is how is it possible to manage environmental flows in a manner that will not exacerbate weed invasion or trigger an increase in abundance of exotic species that are currently present as sleepers in the system?

Aims:

The aim of this project is to determin site indicators that clarify risk status with respect to weed invasion on Murray River Floodplains, and how this risk is affected by changes in flooding regimes and environmental flow allocations. Changes in frequency, duration, depth and spatial extent of flooding forms of disturbance that can have significant implications for wetland and aquatic habitats. The main objects of the project were to:

map weediness coded for local flooding regimes,
analyse local habitat and flooding regime relationships, and
to provide fact sheets indicating management options.

Key questions were identified that specifically address these criteria, including:

Are specific Living Murray Icon sites associated with a higher abundance of exotic species?
Can the spatial location of exotic species in Murray River Floodplains be predicted using hydrological parameters?
Does the distribution of exotic species over time relate to characteristics of the flooding regime?
Are exotic invaders chiefly dry-loving or wet-loving species and has this changed with time?
Can we identify particular site risk indicators which predict vulnerability to exotic plant invasion?

Location

State & NRM Region:

Murray