Equipment/Technology

DNA soil test service alerts growers to pathogens

The Australian potato industry have invested during the past few years in the development of a unique soil test that extracts DNA – which allows for the determination of the presence and intensity of potato pathogens prior to planting.

This service was developed and is provided by the South Australian Research Development Institute (SARDI) to potato growers. Oppressive soil pathogens in Australian potato production regions include powdery scab (Spongospora subterranea) and black dot (Colletotrichum coccodes). During the development of the DNA soil test, base line values have been determined for both these pathogens, along with rhizoctonia and nematodes.

This was done across Australia but adoption has been very strong in Tasmania, the island state of Australia where around 500,000 tonnes of potatoes are produced per annum.

According to Frank Mulcahy, Agricultural Services Research and Development Manager for Simplot Australia, the ability to perform DNA soil tests prior to planting potatoes and thus determining the exact risk of pathogens to quality and yield is an obvious advantage for Tasmanian seed potato growers.

He says annual DNA testing of fields earmarked for potato cultivation to determine suitability and risk is now an acceptable practice in Tasmania.

“The ability to select or reject sites for seed crops has resulted in the highest recovery of certified seed, adding over one million dollars to industry value,” Mulcahy says.

He points out that the ability to test soil in this manner also allows new varietal material to be grown under imitated oppressive conditions of known DNA pathogen values.

“By DNA testing the media and then growing the variety, followed by re-testing the media allows a clinical understanding of what the variety does in the presence of the pathogen and vice versa,” Mulcahy says. “Using this method, Simplot Australia was able to select a specific potato variety with excellent tolerance to powdery scab.  This is variety selection based upon clinical testing to determine susceptibility.”

Although PCR testing occurs in global research institutes for similar testing, the creation of risk thresholds for this particular technology in Australia has evolved through a lot of work.

Mulcahy points out that soil fumigation is not performed in Australia, and never have, so the development of the testing has been a result of that.

Source: This article was first published in Global Potato News magazine