Ascochyta blight is a familiar term to northern chickpea growers. It is one of the most serious diseases of chickpeas in Australia, costing the industry tens of millions of dollars annually in disease control and yield loss.
Caused by the fungus Phoma rabiei (formerly Ascochyta rabiei), the fungus can infect all above ground parts of the plant and is most prevalent when cool, cloudy and humid weather occurs during the crop season.
Now considered to be endemic in all growing regions, Ascochyta blight first caused widespread damage to chickpeas in northern New South Wales and southern Queensland in 1998 when extremely wet conditions favoured disease development and spread. A similar situation occurred last year with Ascochyta affecting a large number of chickpea crops in NSW and Queensland.
A new tool to help chickpea growers minimise the risk of Ascochyta infection in this year’s crops is available with the release of a Grains Research and Development Corporation (GRDC) Know More video detailing Ascochyta blight identification and management.
The video offers a short, simple, step by step guide on symptom identification, environmental influences, sampling procedures and fungicide management recommendations.
Available on the GRDC’s YouTube channel www.YouTube.com/theGRDC or by following this link, the video features one of Australia’s leading Ascochyta blight experts, NSW Department of Primary Industries senior plant pathologist Dr Kevin Moore (picture) who said the pathogen had the potential to cause 100 per cent crop loss in susceptible varieties in a favourable season, if not managed properly.
“Not finding Ascochyta in your crop does not mean that it’s not present. It simply means that it’s at a level where detection is difficult or you don’t have the necessary skills to detect it,” Dr Moore said.
Dr Moore advised growers to check crops 10-14 days after a rainfall event, and to be particular about time of day and the position of the sun.
“As you walk through the crop, it’s important to have the sun behind you or coming over your shoulder. Your eye will be caught by an unusual structure in the canopy; you aren’t looking for individual lesions or fungal structures.
“The Ascochyta fungus can affect any part of the plant except the root system and it usually invades on the stem where the leaf joins the stem.”
Once identified, Dr Moore said growers should consult their agronomist and spray the crop with a registered fungicide at registered rates immediately prior to the next rainfall event.
He said most, if not all, paddocks intended for chickpeas in 2017 may already contain 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.
“This means chickpea plants will get infected during the first post-emergent rain event if they are not sprayed with a registered fungicide before that rain event,” Dr Moore said.
“Evidence collected from chickpea crops and trials during 2016, confirms that the Ascochyta pathogen has evolved with new isolates capable of causing severe disease on varieties like PBA HatTrick. This means growers need to be vigilant with their Ascochyta blight management program.”
For more information, contact Dr Moore on 0488 251 866 or 02 6763 1100, fax 02 6763 1222 or email kevin.moore@dpi.nsw.gov.au, watch the GRDC’s Ascochyta `Know More’ video or visit the GRDC-supported eXtension AUS website www.extensionaus.com.au.
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