New Zealand Journal of Agricultural Research abstracts

Management strategies for an invasive weed: a dynamic programming approach for Californian thistle in New Zealand

M. Chalak-Haghighi

Wageningen University
Environmental Economics and Natural Resources
Bode 129, Hollandseweg 1
6706 KN Wageningen
The Netherlands

E. C. Van Ierland

Wageningen University
Environmental Economics and Natural Resources
Bode 129, Hollandseweg 1
6706 KN Wageningen
The Netherlands

G. W. Bourdôt

AgResearch
Lincoln Research Centre
Private Bag 4749
Christchurch 8140, New Zealand

D. Leathwick

AgResearch
Grasslands Research Centre
Private Bag 11008
Palmerston North 4442, New Zealand

Present address: School of Agricultural and Resource Economics, University of Western Australia, 35 Stirling Highway, Crowley, WA, Australia 6009, morteza.chalak@wur.nl

Abstract Invasive plants can cause significant problems in natural and agricultural ecosystems. Although research has already been conducted on the economics of a single-control option for some invasive weeds, we extended the analysis by developing a dynamic optimisation model that evaluates the net benefits of a range of possible control options simultaneously in order to identify the optimal strategy (mix of control options). This paper focuses on Californian thistle (Cirsium arvense) in pasture in New Zealand. The net benefit is maximised by considering the costs and efficacy of control options, and the monetary value of animal production. Trajectories of shoot density are developed and the optimal strategies are found. Our results suggest that the introduction of a biological control agent (Apion onopordi), in combination with one or more control options, is the optimal strategy when the initial density of the thistle population exceeds 1.0 shoot m^–2. Results show that in the setting of the model excluding MCPA, MCPB and a Sclerotinia sclerotiorum-based mycoherbicide reduces the net present value (NPV) by less than 2%.

Keywords dynamic optimisation; economics; invasive plant, integrated weed management strategy; pasture; New Zealand

A07045; Online publication date 30 September 2008
Received 12 June 2007; accepted 8 September 2008

New Zealand Journal of Agricultural Research, 2008, Vol. 51:409–424
0028–8233/08/5104–0409 © The Royal Society of New Zealand 2008

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