Better modelling for pest and disease freedom

28 Jun, 2011 09:46 AM

RESEARCH at the Department of Agriculture and Food in Western Australia is offering a faster solution to proving area freedom from pest and diseases, without the need for costly and time consuming surveys.

Department research officer Nichole Hammond has developed a methodology that within weeks can draw on already available passive and active surveillance data to confirm the absence of plant pests and diseases, and therefore better assist with future market access.

Ms Hammond said that questions in the past about area freedom involved targeted surveys that could take months to complete.

“Our research has shown that a statistical process, known as stochastic scenario tree modelling, can be used to validate existing surveillance systems and the data produced to support area freedom,” she said.

The project has built on methods developed by the department’s Dr Tony Martin and others to evaluate probability of area freedom for animal diseases, which also use scenario tree modelling.

Ms Hammond said the modelling allowed for whole surveillance systems to be assessed that were made up of different combinations of passive and active surveillance activities.

“Passive refers to detection and reporting through routine activities, including grower reports to government departments, while active refers to both targeted and general surveys,” she said.

“The modelling can calculate as a percentage the level of confidence in the effectiveness of these combined systems, and in the annual data generated by these systems.”

Ms Hammond said there was still a need to test for the pathogens at some level.

“However, in cases where area freedom is questioned, the methodology allows for a faster response,” she said.

As a case study, Ms Hammond focused on the effectiveness of an existing surveillance system used to demonstrate area freedom from the fungal disease Karnal bunt in Western Australia.

Her research included a survey of growers and agronomists to assess the effectiveness of the current passive reporting structure of the WA grains industry.

“The goal was to determine the likelihood that this structure would detect and report Karnal bunt,” Ms Hammond said.

It was the first time the passive surveillance activities of farmers and agronomists had been formally evaluated in WA.

Ms Hammond said the survey included determining grower behaviour through their level of pest/disease knowledge, familiarity with pest advisory and reporting services, the likelihood that the pest would be detected if present, and past reporting behaviours.

“The survey validated the sensitivity of the system, and was able to identify where improvements could be made, such as providing growers with more information on signs and symptoms of exotic grains pests,” she said.

The research also looked at the effectiveness of active surveillance activities.

“The resulting data, when inputted into a scenario tree model for Karnal bunt, calculated that the existing surveillance system for this pest provided more than 90 per cent confidence of area freedom,” Ms Hammond said.

The CRC for National Plant Biosecurity supported PhD research project has received widespread interest from Australia’s biosecurity community.

Ms Hammond said the data collected through the project could be used in future to assess, through the scenario tree model, the sensitivity of the current surveillance systems for threats such as barley stripe rust, Russian wheat aphid or Khapra beetle.

Modelling could also be applied to other plant threats both in WA and other States, depending on existing data.

“Future applications of the modelling include identifying the need for additional surveillance activities as part of an overall system, comparing existing surveillance programs, or designing new programs,” she said.

“When applying the scenario tree model to other plant pest or disease systems, useful data could include crop trials, seed testing, research projects and sampling

WA Department of Agriculture and FoodSource:
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2/07/2011 9:07:36 PM, on Farm Weekly

Of course they will need other surveilance methods as the department has lost most of the experienced staff in the biosecurity area ie APB, and are retreting back to south perths taj mahal.


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