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DNA abundance: A new diagnostic tool, 2020 to date.
  • PREDICTA B: A comprehensive approach
DNA v's ppg
Dry plating - ppg counts
Measuring propagules per gram of soil (ppg) to assess Sero-X's impact for APVMA registration was a labour-intensive process that is not commercially viable as a diagnostic tool that could be used across the industry.
While this approach was perfect for generating the data on the effectiveness of Sero-X in managing Verticillium wilt, it was not a practical solution for large-scale commercial use.
With our goal being to determine rate and timing responses and to better understand when growers should or should not use Sero-X, alternative diagnostic tools were to be explored.
qPCR: PREDICTA B® & Crown Analytical Services
In 2011, Crown Analytical Services (CAS) partnered with SARDI to provide qPCR PREDICTA® B soil and stubble-borne disease DNA tests in the northern growing region. Since then, they have collaborated to develop a testing protocol for measuring the Verticillium dahliae pathogen.
This measurement encompasses the DNA of all pathogen stages, including conidia, hyphae, and microsclerotia.

PREDICTA B® from SARDI - South Australian Research and Development Institute gives a result in Picograms of DNA per Gram of soil (pgDNA/gm/sample), offering a simple and efficient testing process where one soil sample can be analysed for multiple diseases.

2020-21: Scoping study

With thanks to CSD and the growers for allowing us to use their trial field a large plot scoping study commenced on two sites with existing trials. Aim: Monitor changes in DNA abundance in the soil over time to determine the impact Sero-X has on DNA levels and assess the viability of DNA abundance measurement. At both sites applications were shown to limit the increase of DNA. Site 1 showed that the defoliation application may have been the most effective treatment due to the highest level of DNA reduction. More data points are required. Scoping study discussion Site 1 showed that the defoliation application may have been the most effective treatment due to the highest level of DNA reduction, but there was not enough data to be conclusive.

PREDICTA B: A comprehensive approach
All stages, living and dead.
PREDICTA B qPCR DNA abundance measures all stages of the Verticillium dahliae pathogen, both living and dead cells.
Microsclerotia: The long-term threat.
This means that the parasitic stage, which doesn't survive long in the soil, is detected in equal measure to microsclerotia, the hardened structure that can remain viable for up to 14 years.