A successful model for community-driven research: the Hieracium Control Trust in New Zealand.

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Pauline Syrett and Lindsay Smith

Landcare Research, PO Box 40, Lincoln, 7640, New Zealand.

David Scott

4 Murray Place, Lake Tekapo, 7999, New Zealand.

Sue Aspinall

90 MacPherson Street, Wanaka, 9305, New Zealand.

Cite this article as:

Syrett, P., Smith, L., Scott, D. and Aspinall, S. (2013). A successful model for community-driven research: The Hieracium Control Trust in New Zealand. Plant Protection Quarterly 28(2), 57-63.


The Hieracium Control Trust (HCT) was established in 1992 by a group of farmers keen to promote the development of a biological control programme for Pilosella and Hieracium spp. (hawkweeds), with support from Landcare Research and AgResearch. Over 15 years, the HCT raised over NZ$2 million to fund the survey, screening and introduction of one pathogen and five insect control agents. Releases were made at over 260 sites and control agents have been recovered from over 150 sites. Although agents released have been slow to impact on hawkweed populations, recent data from the North Island indicated that hawkweed gall midges were responsible for a 26% reduction in hawkweed cover. The HCT also leveraged about NZ$500 000 from the Foundation for Research, Science and Technology (FRST), which was used to fund complementary work to assess the significance of existing phytophagous species feeding on hawkweeds and to conduct a simulation study of successful biological control. The hawkweed biological control programme generated in excess of eight refereed papers, 8 conference papers, two PhD theses and 20 reports. Direct funding came from more than 30 organizations, as well as individual farmer contributions. This model, established by the HCT, was adopted by other programmes, both in New Zealand (for broom and Californian thistle) and overseas (for hawkweeds in Idaho and Montana).


Hawkweeds (Hieracium and Pilosella spp., Asteraceae) originate from the Northern Hemisphere. Several European hawkweeds are regarded as problem adventive (non-native) weeds in New Zealand’s modified tussock grasslands. Pilosella officinarum Vaill. (=Hieracium pilosella L.) (mouse-ear hawkweed) is the most common and widespread, although at least three others have also been identified as causing concern (Hunter 1991). These are Pilosella piloselloides subsp. praealta ((Gochnat) S. Bräut. & Greuter) (=Hieracium praealtum Vill. ex Gochnat) (king devil), Pilosella caespitosa (Dumort.) P.D. Sell & C. West (=Hieracium caespitosum Dumort.) (field hawkweed) and Hieracium lepidulum (Stenstr.) Omang (tussock hawkweed).

In the 1980s, concern about hawkweed invasion led a number of research organizations to investigate the distributions of the problem species and their interactions with existing vegetation, as well as the biology and ecology of individual hawkweed species, as a means of developing techniques for their management (Scott 1985, Hunter 1991, Hunter et al. 1992). Among these, the New Zealand programme for biological control (hereafter biocontrol) of hawkweeds was initiated by Dr David Scott (initially with Grasslands Division of Department of Scientific and Industrial Research and latterly with AgResearch).

In 1992, the Crown Research Institutes encouraged a new, user-pays style of research funding, causing a group of concerned high country farmers with a long-standing interest in the problem of hawkweeds to enter into discussion with Landcare Research scientists working in weed biocontrol (primarily with insects at that time) and Landcare Research management, leading to the establishment of the Hieracium Control Trust (HCT) in 1993. It took the form of a charitable trust, formed by the High Country Committee of Federated Farmers, with the mission statement: ‘To ensure the development and implementation of biological control of Hieracium and restoration of affected areas’ (Anon. 1993). The HCT comprised 3–4 trustees and a similar number of science advisors. Federated Farmers provided accounting services and Landcare Research provided secretarial support. The HCT’s business plan was initially for a period of 10 years, but ongoing activities led to an extension for a further 10 years. The HCT concluded its last funded project in 2010 and was disbanded in 2013.

The HCT raised funds directly from affected farmers and an annual newsletter kept the farmers informed of progress. Trustees wrote numerous grant applications and lobbied government and non-governmental organizations for support. One of the HCT’s first roles was to coordinate biocontrol activities between different research providers.

Prior work on pathogens for the biocontrol of hawkweeds was summarised by Scott (1993). In 1983, Dr David Scott visited Europe to study hawkweeds in their native ranges and made contact with researchers at the Royal Botanic Garden in Edinburgh, United Kingdom. In 1987, he returned to Europe on sabbatical for several months to make field collections of various strains of the rust fungus Puccinia hieracii (Röhl.) H.Mart. var. piloselloidarum (Probst) Jørst. from Pillosella officinarum, learn details of the rust infection process and determine the relative pathogenicity of the strains. Later, he helped Dr T.A. Jenkins gain funding from the Miss E.L. Hellaby Indigenous Grasslands Research Trust for a PhD fellowship to study fungal biocontrol of hawkweeds (Jenkins 1995).

In 1993, Landcare Research made contact with a PhD student in Hungary whose study of the phytophagous insects on P. officinarum provided relevant data (Syrett and Sárospataki 1993). These initial studies provided the background for the development of a biocontrol programme, and CAB International in Switzerland was approached to continue the search for suitable agents and conduct host testing.

This paper documents the achievements of the Hieracium Control Trust in terms of direct fund-raising and disbursement of money to research providers through a bidding process, the scientific and practical achievements of funded work, the outputs from leveraged funding of supporting research from the Foundation for Research, Science and Technology (FRST), and secondary or spinoff benefits from similar programmes set up by other organisations using the HCT as a model. The overall success of the HCT is discussed using several measures (Syrett et al. 2000): financial outcomes (dollars raised); research outcomes (information learned and passed on to the community); practical outcomes (numbers of agents released and established and the degree to which the weed problem has been alleviated); and outcomes flowing from the HCT programme being seen as a model for the development and management of other weed biocontrol programmes.

Financial outcomes

Over the 17 years of the HCT’s active life, more than NZ $2 million was raised (Table 1) from more than 30 organisations as well as a large number of individual farmers. The majority of the HCT’s income was spent on biocontrol of hawkweeds (Table 2). The administrative budget was minimal, and a modest investment was made in restoration research (Table 2).







Research outcomes

Biocontrol: surveys for pathogens and insects

At the time of the HCT’s formation, a survey for pathogens on Pilosella officinarum was already underway in Europe (Jenkins 1995) and a student was studying insects feeding on P. officinarum in Hungary (Sárospataki 1999). With initial funding from the New Zealand Wool Board, the HCT commissioned Landcare Research to initiate a biocontrol programme with insects. CAB International (CABI) in Switzerland was commissioned to undertake field surveys, identify field collection sites and identify the most promising species for introduction (Jordan 1993, Syrett 1993). From the literature, Jordan (1993) identified over 30 insect species reportedly monophagous on Pilosella and Hieracium spp. Eight of these were collected during field surveys in Europe, and four were selected for further study (Grosskopf 1995). A survey of the four problem hawkweed species was conducted throughout their distribution in New Zealand to see whether any exotic or native insects that were damaging them might have potential as biocontrol agents. None were found (Syrett et al. 1994).

Biocontrol: studies in native range of biocontrol agents

The HCT funded work by T.A. Jenkins and L.M. Morin on the rust fungus Puccinia hieracii var. piloselloidarum in Europe. Tests indicated that this rust was sufficiently host-specific for introduction and a case was made for its importation to New Zealand before it was discovered as already present in 1995. A number of isolates from different locations through Europe, and later isolates of the newly discovered strain in New Zealand, were tested for relative pathogenicity (Jenkins 1995). Morin and Syrett (1996) showed that collections of P. officinarum from different areas, both in Europe and New Zealand, showed differing levels of infection, from 0 to 100%, and that the difference in susceptibility of plant collections was greater than the differing levels of infectivity between isolates of the rust. In 1998, two further promising strains of the rust were identified in Ireland (T.A. Jenkins personal communication).

Oxyptilus pilosellae Zeller (Pterophoridae) was the first insect agent to be investigated, and tests in Europe in a glasshouse and in field cages showed it to be host-specific to Pilosella and Hieracium species, with a preference for P. officinarum and P. caespitosa (Syrett et al. 1997). The second agent tested was the gall wasp, Aulacidea subterminalis Niblett (Cynipidae), which attacked only P. officinarum and P. aurantiaca (L.) F.W.Schultz & Sch.Bip. (Syrett et al. 1998), followed by the gall midge Macrolabis pilosellae (Binnie) (Cecidomyiidae), which attacked the three most weedy Pilosella species (Syrett et al. 2001). Two hover flies (a second species was found during research on the first) – the root-feeding Cheilosia urbana Meigen (formerly C. praecox (Zetterstedt)) and the crown-feeding C. psilophthalma (Becker) (Syrphidae) – complemented the suite of insect agents predicted to be the most promising for control (Grosskopf et al. 2002, Grosskopf 2005).

When Hieracium lepidulum was identified as a priority target for biocontrol on Department of Conservation (DOC) lands (Syrett 2002), New Zealand seed of this hawkweed was sent to Switzerland in preparation for research on potential insect control agents. However, further funding was not available and this project ended.

Measuring agent impact

In spite of doubts expressed by some ecologists at the outset of the biocontrol programme that it would solve the hawkweed problem (Treskonova 1991), the prospects for successful control with available agents appeared promising (Syrett et al. 2001). Seed-feeding control agents were not given high priority, as their effectiveness would be limited by the perennial habit and vegetative spread of hawkweeds. The agents selected were those that showed potential to damage the vegetative parts of the target plant. Even though they rarely reached damaging levels in their native Europe, it was predicted that (like other biocontrol agents and introduced pest species) they might reach higher population levels in their exotic range, where they would establish without their native parasitoids and predators. A protocol was designed for monitoring establishment and impact of biocontrol agents for hawkweeds (Syrett and Smith 2001). From 2001 to 2004, at four sites in each of three regions (Marlborough, Canterbury and Otago), vegetation was monitored annually to measure the impact of gall wasps released into two of the sites in each region. Gall wasps established at only three of the six sites where they were released, and no difference was recorded between sites with and without gall wasps, probably because the insect populations had had too little time to build up to significant numbers (Newell and Smith 2004). Relatively long lived, vegetatively reproducing, problem hawkweed species are unlikely to succumb rapidly to biocontrol agents whose reproductive capability is likely to be limited by the low productivity of the environments in which hawkweed thrives.

In 2003, the HCT gained Ministry of Agriculture and Forestry Sustainable Farming Fund (SFF) 3-year funding (later extended to 6 years), and field trials were established at three locations on two high country properties (Glenthorne Station, Canterbury, and Galloway Station, Otago) to measure the impact of gall wasps and gall midges on hawkweeds and other vegetation. These trials were sited on areas where vegetation history was well known through existing vegetation transects that had been monitored for a period of 20–40 years. In total, 12 release sites and three control sites were established for each biocontrol agent, each release site receiving either two gall wasp or four gall midge releases over two seasons (2002–04). For three years (2001–04) annual monitoring was carried out along two 40-m-long transects at each site across areas where gall wasps and midges were released and along six similar transects across areas where no releases were made. As no differences were apparent, further releases were made in 2004/05 (Newell et al. 2006). Establishment from these releases was poor; no gall wasps were recovered, and only low numbers of gall midges were recorded, although they were found at all 12 release sites. This poor establishment could possibly have been because of adverse climatic conditions (the summers were very dry), and unsurprisingly resulted in no impact on vegetation being recorded (Newell et al. 2009).

An additional objective for the second SFF grant was to investigate the impact of gall midges on the growth of three hawkweed species under differing nutrient and simulated ‘grazing’ conditions in the laboratory. Midge galling reduced the total stolon length of P. caespitosa and P. piloselloides, but increased stolon branching and hence total stolon length of P. officinarum.  Mean stolon length was also shorter in plants with no added nutrients.  (Newell et al. 2009).

Ecology of hawkweed

The HCT was able to devote few resources to this area of research relative to the large amount of research being funded by other providers. However, through the SFF grant, Dr Barry Wills continued a study of the ecology of hawkweed invasion in the Upper Manorburn, Central Otago, begun in 1982. Monitoring at this site over a 25-year period documented the effects of aspect on fluctuation in cover of hawkweeds relative to other vegetation and bare ground components of ground cover. Pilosella officinarum stabilised at 50–60% cover in the most susceptible microsites, while other hawkweed species, H. lepidulum in particular, increased their cover during the study (Newell et al 2009).


The HCT also funded a small amount of research aimed at restoring hawkweed- invaded pastoral land. In its early days, the HCT supported an AgResearch project to establish a seed orchard to determine which plants, both native and adventive, might have potential for use in revegetation of affected grasslands. Seeds from five native tussock species and two adventive grass species were collected by hand, but as the HCT was unable to fund further work, AgResearch used the collected seed in further studies with alternative funding (Scott et al. 1996). The HCT was very supportive of this work, but felt it necessary to use its limited funds to develop the biocontrol programme.

Transfer to the community of information learned 

The HCT produced an annual newsletter, which reported research progress as well as agent release and recovery information. The hawkweed biocontrol programme generated in excess of eight refereed papers, eight conference papers, two PhD theses and 20 reports. Pages on hawkweeds, and the agents introduced for its control, were produced by Landcare Research in its Biological control of Weeds book (Hayes 1999). Landcare Research also held field days for farmers, and included hawkweed biocontrol content in workshops held for regional council and DOC staff.

Practical outcomes

Agent approvals

Importation Impact Assessments were conducted for the hieracium plume moth Oxyptilus pilosellae (Syrett et al. 1997) and the hieracium gall wasp Aulacidea subterminalis (Syrett et al. 1998). Approvals from the Ministry of Agriculture and Forestry (now the Ministry for Primary Industries) were gained for release of both agents.

Three further agents were proposed for release under new legislation, the Hazardous Substances and New Organisms Act 1996 (Syrett 1999). In 2000, the HCT applied to the Environmental Risk Management Authority for the release of the hieracium gall midge (fly) Macrolabis pilosellae, the root-feeding hover fly Cheilosia urbana Meigen and the crown-feeding hover fly C. psilophthalma. The application was approved in 2001 (EPA 2001).

Agent release and establishment

Over the lifetime of the HCT, releases were made at over 260 sites and control agents were recovered from over 150 sites (all agents). Three of the agents (the rust fungus, gall wasp and gall midge) established widely, but recoveries have not been made of the other three. It is unlikely that they have established.

In 1995, before application was made for its release, the rust Puccinia hieracii var. piloselloidarum was discovered in New Zealand (Morin and Syrett 1996). Efforts were made to distribute it widely to enhance its impact (Jenkins 1997, Morin et al. 1997). Jenkins (1998) showed that only 37% (range 8–60% across sites) of P. officinarum plants tested were infected by the New Zealand strain of the rust. Therefore, he proposed the introduction of two new isolates from Ireland, to one of which, in particular, New Zealand plants were more susceptible to (T.A. Jenkins personal communication). These new strains were released throughout the South Island and at two North Island sites. The rust established and spread from one of the North Island sites (near Taupo), and has been spreading, albeit slowly, from most of the release sites on the South Island that have been checked. However, infection levels have been low, as was observed in its native Europe (T.A. Jenkins personal communication).

A powdery mildew, Erysiphe cichoracearum DC., is common and highly pathogenic on Pilosella and Hieracium spp. throughout Europe (Jenkins 1995). It is established in New Zealand, also occurring on many other members of the family Asteraceae (Anon. 2007). However, the species may comprise physiological races that are more host specific to hawkweeds. It can be damaging to hawkweed, especially in sheltered areas where humidity is highest (T.A. Jenkins personal communication).


A summary of the number and size of releases made of the five insect biocontrol agents is presented (Table 3). Locations of releases of the gall wasp (Aulacidea subterminalis), gall midge (Macrolabis pilosellae), and the other three insect control agents are shown in Figures 1, 2 and 3 respectively.

While gall wasps and gall midges established widely, the plume moth proved difficult to rear, and from the few moths released, no recoveries have been made. Two hover-fly species, feeding on different parts of the plant, were also released but no recoveries have been made.

Six seasons after release, the maximum densities of each gall former recorded were 120 gall wasp chambers, and 1.2 plants m-2 infested with gall midges (Smith et al. 2008). Although there has been less follow-up on releases over the last few years, populations of gall wasps and gall midges have reached sufficiently high levels at some release sites in the south of the South Island that Environment Southland has collected and redistributed these agents to new areas (J. Bythell personal communication). Monitoring of gall wasp and gall midge populations, funded by the New Zealand Defence Force, has continued at North Island sites. Between 2006 and 2012 gall midges reduced the cover of hawkweed by an average of 26% across 5 sites (Peterson et al. 2013).







Achievements of biocontrol programme through leveraged and contributory funding

As a result of its active support of hawkweed control, the HCT was identified as a stakeholder in Landcare Research’s invasive weeds programme funded by FRST, and its research needs were considered in negotiating the content of the programme. Within this programme, approximately $500 000 of FRST funds was directed towards research into hawkweeds during the life of the HCT. In 1993, an experiment was initiated to simulate biocontrol of hawkweeds in order to measure the response of other vegetation to the gaps that would be created according to the predicted impact of the biocontrol agents (Syrett et al. 2012). This project ran for nineyears, and within that time frame, no other vegetation invaded the artificially created gaps, raising some doubt regarding the benefits of biocontrol. The assessment of the insect fauna of hawkweed in New Zealand, funded by the HCT, was published under Landcare Research’s invasive weeds programme (Syrett and Smith 1998).

Another project funded partially by FRST, and carried out by a visiting German student, was to predict the impact that the introduced gall wasp would have on P. officinarum plants growing under different environmental conditions (Klöppel et al. 2003). A shade house study showed that the gall wasp performed equally well on stressed plants, indicating that it could be effective in areas where P. officinarum grows in low nutrient soils with a water deficit – habitat typical of much of the hawkweed-infested countryside.

By funding studies on host selection of hawkweed-feeding insects in Europe as potential control agents in New Zealand, the HCT contributed to understanding the ecology of these insects in their natural habitat (Grosskopf 2006). The HCT also contributed to increasing knowledge of the ecology of invasive hawkweeds in New Zealand by providing financial assistance to a student project on the colonising success of P. officinarum (Chapman et al. 2000).

Indirect achievements of the HCT

Biocontrol of hawkweed

The successful establishment of the gall wasp and the gall midge led the New Zealand Army to contract Landcare Research to release and monitor the two agents on their land in the Central North Island. Gall wasps established at one of the 19 sites, while gall midges established at 11 of 13 release sites and dispersed from these sites (Peterson et al. 2010). Gall midge densities were sufficiently high at five sites to reduce hawkweed cover by 26% between 2006 and 2012 (Peterson et al. 2013).

This community-based support model has been adopted elsewhere. The University of Idaho encouraged landowners in Northern Idaho to establish the Hawkweed Action Committee Inc. (HACI), with the purpose of raising awareness and funds to tackle the hawkweed problem (P. caespitosa and P. aurantiaca). The non-profit organisation comprised county weed control personnel, state and federal land and wildlife management agencies, the Coeur D’Alene Tribe, and representatives of private industry as well as concerned landowners (Anon. 1995). A prospectus similar to that of the HCT was circulated, and the first issue of ‘Hawkweed News’ was produced in February 1995. Some money was raised to support hawkweed management and biocontrol, but the greatest achievement was in raising awareness of the hawkweed problem (L.M. Wilson personal communication). The newsletter was replaced by a website in 1999, and the Hawkweed Biocontrol Consortium expanded to include Montana, Washington and British Columbia (Canada) (Hawkweed Biocontrol Consortium 2008). CAB International continues to carry out work for this group on potential control agents for hawkweeds, even though the HCT no longer contributes to that research.

Biocontrol of other weeds

Two other community groups concerned about invasive weeds successfully followed the example set by the HCT. The Amuri Broom Group (from 2004, the Canterbury Broom Group), formed in 1995, gained funding to release three new agents for the biocontrol of broom (Cytisus scoparius (L) Link) (SSF 2013b). The Californian Thistle Action Group (CalTAG), set up in the late 1990s, successfully gained funding for a project to test, import and release Urophora cardui (L.) for control of Californian thistle (Cirsium arvense (L.) Scop.) (SSF 2013a). Although this insect proved ineffective, additional funding in 2005 allowed the importation and release of two new control agents for Californian thistle (A.H. Gourlay personal communication).

Developing regulatory policy and practice

Research funded by the HCT has contributed to developing policy and practice for the regulation of importation of biocontrol agents. The application by the HCT for the release of three insect agents for biocontrol of hawkweeds (Macrolabis pilosellae, Cheilosia urbana and C. psilophthalma) was used as a case study in evaluating the Environmental Risk Management Authority’s process for approving the release of biocontrol agents under the Hazardous Substances and New Organisms Act 1996 (Barratt and Moeed 2005).


The HCT raised a significant amount of money for research and application of hawkweed management. The trust was effective in maintaining interest from the farming community over an extended period, and funding relevant research to achieve the introduction and establishment of three agents for biocontrol of hawkweed. Projects for assessing the impact of control agents were also funded, and it may be only because of the long-term nature of this programme that results have been inconclusive within the time frame of the trust’s existence. It is significant that this community group was sufficiently concerned about an invasive species causing economic and environmental losses to devote resources and to lobby for a solution that was expected to take many years to come to fruition.

Measuring the success of biocontrol is a challenging process (Syrett et al. 2000). Although three agents have established, the New Zealand programme for biocontrol of hawkweed may or may not be highly successful in terms of achieving measured reductions in the hawkweed problem. Most biocontrol programmes take several decades to achieve potential benefits, so it may still be too early to gauge their success, especially in ecosystems where harsh environmental conditions slow biological processes (McClay 1996). It is encouraging that in Southland, at least, populations of insect control agents are sufficiently high for redistribution to new areas.

The HCT’s greatest success may have been in establishing a model for community-driven research that allowed a community group to identify a problem, a potential solution, and to gain funds through lobbying and putting their hands in their own pockets to implement that solution. Several similar groups have successfully funded biocontrol programmes with varying outcomes in terms of funds raised, research undertaken, and weed management changes implemented.


This paper is dedicated to the late John Aspinall, Chairman of the Hieracium Control Trust from 1995 to 2010, whose drive and commitment ensured the success of the trust. His well-developed negotiating skills were employed to great effect both with potential funding agencies and with research organisations to achieve the HCT’s goals. We also acknowledge the dedicated support of the other trustees – Edwin Pitts, John Chapman and the late Allan Innes – and the contributions of others who supported the HCT in a variety of ways: Bob Douglas, John Keoghan, Allison Kerr, Brian Molloy, Oliver Sutherland and Heather Thomas. We would also like to thank Hugh Gourlay for providing information on the broom and Californian thistle projects. We are also very grateful to Christine Bezar for editing the manuscript for us, and to two anonymous referees for helpful comments.


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First published online: June 24, 2013