Economic thresholds for the major pests reducing profitability in the Australian grains industry
Grains Research and Development Corporation | Published January 9, 2017 - Deadline February 20, 2017
The Grains Research and Development Corporation (GRDC) is a statutory corporation established under the Primary Industries Research and Development Act 1989. It is subject to accountability and reporting obligations set out in the Public Governance, Performance and Accountability Act 2013. It is responsible for planning, investing in and overseeing research and development, and delivering improvements in production, sustainability and profitability across the Australian grains industry. Thresholds are not known for many insects. There are also questions as to the reliability of the published thresholds. How, where and when was the data generated and is it still relevant? Has a change in crop type, architecture, management and resistance levels (e.g. midge resistance, more pods on canola branches) changed the economic threshold? Is there an effective means of developing thresholds? Can data be generated using a region wide paddock sampling program and/or modelling? There are over a hundred invertebrate species that damage crops in the Australian grains industry. The presence of a pest in a crop is not an automatic trigger for control. Attempting to prevent all damage is usually uneconomic. Economic thresholds (ETs) help to rationalise the use of pesticides, and are one of the keys to profitable pest management. ETs can be defined as the pest population size likely to cause damage equal in value to the cost of control (pesticide plus application). The GRDC Grains Pest Advisory Committee (GPAC) recently produced a paper, ‘Economic thresholds for pest management in the grains industry’. After a review of ETs (2014), it was revealed that in most cases none existed or those that did had limited usefulness. The grains industry requires additional and better thresholds that can guide their judgments on pest control. The following methods are available to establish ETs: 1. An evaluation of existing tacit knowledge held by experienced agronomists and entomologists, then testing the validity of the existing ETs. 2. Undertake detailed field and laboratory research (most expensive approach; would only be justified for key pests for which the potential impact on crops cannot be estimated). 3. Computer modelling and simulation. These mechanisms provide valuable and much less expensive ways of examining complex biotic and abiotic interactions that might influence ETs, and provide scope to assess the performance of nominal thresholds. However, the need for research to establish the crop loss inflicted by each species is likely to remain, as it is a key component of modelling interactions between plant and pest. Similarly, the use of proxies for ETs, such as risk factors, can be a legitimate and practical alternative approach. 4. Determination if a nominal (subjective, without an empirical basis) or dynamic (flexible, e.g. seasonal price fluctuations) threshold is required. This GRDC investment is to deliver: By October 2017, a written report delivered to GRDC describing the plans to determine thresholds and a priority listing of crop x pest thresholds for each region. The report will include findings from at least 5 information-gathering workshops held in each region, and will include input from SAGI regarding statistical analysis of proposed trials. Detail At least 5 regional information-gathering workshops are to be convened in each GRDC region (North, South and West). The workshop convener will in consultation with the GRDC, first identify, engage and select relevant experts, including key agronomists and entomologists, to participate in each of the workshops. Workshop participants will assist to propose suitable methodology to undertake the work on the pest x crop priorities for each region, as identified in the report prepared by the Grains Pest Advisory Committee (GPAC). The report will include: • Tacit knowledge used by agronomists on thresholds. • Justified priority listing of pest x crop for each region. • Proposed methodology to determine thresholds (e.g. field experimentation, glasshouse microcosm, field evaluation of tacit knowledge of agronomists, field validation from other regions, computer modelling and simulation) and why this method was chosen over other methodologies. • Incorporation of beneficials into the dynamic thresholds, where appropriate. • Consideration of crop recovery factors. • Consultation with SAGI regarding the proposed field trial numbers/designs etc. The report will be submitted to the GRDC for approval prior to any further work occurring.