Preliminary PREDICTA® B results show prevalence of Ascochyta inoculum

Growers are now able to utilise the PREDICTA® B DNA-based soil test to detect the presence of Ascochyta blight inoculum (Phoma rabiei) in their paddocks. Initial testing has shown that the Ascochyta fungus was detected in 35 per cent of samples from the Northern Region. This finding is a concern for growers who are contemplating planting chickpeas and led to the test results being reported on PREDICTA® B reports to growers in the northern regions as a test under evaluation.

Figure 1 Ascochyta blight (Phoma rabiei) population density in PREDICTA® B and NVT sites in 2017

Figure 1 Ascochyta blight (Phoma rabiei) population density in PREDICTA® B and NVT sites in 2017 (Click image to view full size)

Figure 1 shows the results from samples submitted prior to sowing the 2017 crop. This has provided an overview of relative prevalence of Ascochyta inoculum in the Northern Region where the majority of samples were taken. The categories presented are based on a range of population densities, not disease risk categories. These results will be ground-truthed throughout 2017 in the Northern Region by Dr Kevin Moore, in an attempt to calibrate the pre-sowing PREDICTA® B results with disease incidence in the following chickpea crop.

Following a high incidence of Ascochyta Blight last year, and a reported 60 percent of the Northern Region cropping area planted to chickpeas in 2017, the results are a timely reminder of the inoculum left behind with chickpea residue and its potential to impact subsequent crops. The high levels of disease in some areas is also a reminder that growers need to think twice about risk of all diseases, particularly when planting chickpeas back-to-back.

Although limited samples were submitted for Ascochyta assessment in the Southern Region, the results are a reminder that the pathogen is carried over in paddocks and this should be taken into account when planning paddock selection and crop rotations. Knowledge of the distribution of inoculum in the Southern Region will only grow with further PREDICTA® B testing.

For both the Northern and Southern chickpea growing regions, growers need to be well aware of the Ascochyta risk and plan ahead for fungicide applications. Growers are urged to not only budget for fungicide applications ahead of time but also have an appropriate number of applications ready in the shed.

Accessing PREDICTA® B to test for Ascochyta blight

If Dr Moore’s assessments this growing season confirm that the results do help chickpea growers with paddock selection and early fungicide application, then results will be included on all PREDICTA® B reports nationally in 2018. More information on the use of PREDICTA® B for assessing Ascochyta blight inoculum is available here. Details on how to access PREDICTA® B testing in the two chickpea growing regions is provided below.

Northern Region

Crown Analytical Services coordinates PREDICTA® B for the Northern Growing Region. You can contact Crown Analytical Services on 0437 996 678 or crownanalytical@bigpond.com.

Southern Region

Southern Region growers should contact their PREDICTA® B accredited agronomist or contact Nigel Percy for accredited consultants near you.

Further information

Acknowledgements

Alan McKay, SARDI

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