The worm's fingerprints: Quick test for root diseases

Tracking DNA through the soil. A system that allows a quick and thorough search for soil villains.

Genetic engineering may have garnered all the popular press but, for farmers, DNA fingerprinting is one side of the biotechnology revolution offering big immediate returns.

Rapid diagnostic technology developed through the Cooperative Research Centre for Plant Science can now pinpoint cereal cyst nematode, root lesion nematodes and Ascochyta. As well, a fuller range of tests for major fungi is coming on-line next season.

It's done by analysing the base sequence of a specific bit of DNA in an individual nematode of fungus. The selected DNA is chosen because it will show differences between individuals or between species. It works not only for forensic science but also for isolating the bad guys in the soil profile.

According to project leader John Curran from CSIRO Entomology, the technology can identify multiple pathogens from a standard soil sample and outperforms other current testing methods in terms of time and money.

The system has been streamlined with robotics and is now part of the root disease testing service offered by the South Australian Research and Development Institute (SARDI). Development partners of the Centre are Rhone-Poulenc and the Rural Industries Research and Development Corporation (RIRDC).

Rapid diagnosis for farming systems

Chemicals, cultural control methods such as crop rotation, and the development of resistant plant varieties all require knowledge of soil pathogens and their numbers — information that until now has been time-consuming and costly to obtain.

"The ability to provide multiple tests in one sample not only reduces cost, it also provides a more complete picture of soil health," said Dr Curran. "Consultants and agronomists can combine the findings with nutritional analysis to provide more comprehensive advice to growers.

"The tests are already revealing patterns of disease on farm and at a regional scale and will help unravel the links between soil fertility, disease status, productivity and sustainability."