New South Wales and Queensland growers can now potentially make more informed decisions on paddock selection in the lead up to the 2017 chickpea plant following the announcement that the DNA-based soil test PREDICTA® B will incorporate a test for Phoma rabiei (Ascochyta blight).
The South Australian Research and Development Institute (SARDI) recently decided to include the test on PREDICTA® B reports as preliminary results have found that the assay is detecting Phoma rabiei (previously Ascochyta rabiei).
SARDI Research Leader, Soil Biology and Diagnostics Dr Alan McKay said the test was being evaluated for its effectiveness in supporting management decisions by raising awareness of baseline inoculum levels.
“This year we have started reporting Phoma rabiei (Ascochyta blight) results to growers as a test under evaluation. The decision to do this was made following initial testing that showed the fungus could be detected in about 35% of samples from the northern cropping region, which is concerning if growers are contemplating growing chickpeas,” Dr McKay said.
Paddocks earmarked for sowing to chickpeas in 2017 can be assessed for potential disease risk. Once growers receive their PREDICTA® B test report, they should email the sample identification to NSW Department of Primary Industries (NSW DPI) senior plant pathologist Dr Kevin Moore.
“SARDI will provide Dr Moore with the Ascochyta results of all PREDICTA® B samples from the northern region but without the client details,” Dr McKay said.
“He will then collate information on the chickpea crops grown in paddocks tested by PREDICTA® B to determine if the Phoma rabiei results can be calibrated for disease incidence.”
Dr Moore said most, if not all, paddocks intended for chickpeas in 2017 may already contained the Ascochyta fungus due to being inoculated with infected chickpea residue during the 2016 harvest, and also possibly with residue from Ascochyta-infected 2015 and 2014 chickpea crops.
“It’s extremely likely that the pathogen is already in your 2017 chickpea paddock. A PREDICTA® B assessment of stubble samples will give growers and advisors an objective assessment of how much Ascochyta is present in their samples as well as information on other pathogens such as crown rot and root lesion nematodes,” Dr Moore said.
“During the 2017 season, I’ll inspect crops throughout the northern region to capture actual levels of Ascochyta and this crop `truthing’ will then be used to calibrate and evaluate the test.
“This evaluation is essential if the PREDICTA® B Ascochyta test is to play a meaningful role in future disease management decisions.”
Crown Analytical Services (CAS) is the service co-ordinator for the northern region PREDICTA® B test.
CAS directors Rob Long and Drew Penberthy believe the PREDICTA® B test has potential to provide additional valuable information for growers, particularly in relation to chickpea paddock selection, prioritising early fungicide applications and longer term rotation planning.
“It has the potential to help growers rank paddocks according to their relative starting Ascochyta blight inoculum levels – it could even provide a measure of the difference in inoculum levels between paddocks that grew chickpeas in 2014, 2015 and 2016 and identify higher risk situations.
“The northern PREDICTA® B test already provides results for a number of other pathogens relevant for numerous crop types, adding Ascochyta makes it an extremely versatile and valuable decision making tool.”
PREDICTA® B kits can be obtained from Crown Analytical Services. They can be contacted on 0437 996678 or email@example.com for more information.
The GRDC has also developed a Know More video to give chickpea growers a new tool to identify and manage Ascochyta blight. The video features Dr Moore and offers a short, simple, step by step guide on symptom identification, environmental influences, sampling procedures and fungicide management recommendations. The video Pointing the lens at Ascochyta blight - K.Moore | 2017 Know More series | Northern Region is available on the GRDC’s YouTube channel.
Cox Inall Communications