On 8 July, Dr Kevin Moore, plant pathologist based at NSWDPI, Tamworth, confirmed chickpea Ascochyta blight in a crop of Flipper at North Star NE Moree. From then to 10 August, Kevin found the disease in 27 crops, mostly in the Gulargambone, Armatree, Collie, Warren, Trangie region and around Yallaroi and North Star. With the exception of the Flipper crop at North Star, all the infected crops are believed be PBA HatTrick which is rated MR to Ascochyta blight. There is also one report of Ascochyta in PBA Boundary (also MR) at Forbes.
Chickpea agronomists and growers are encouraged to check all chickpea crops including those with improved resistance to Ascochyta e.g. PBA HatTrick and PBA Boundary.
If Ascochyta is suspected please send plant samples wrapped in newspaper to Kevin or Sue. Please include the following with the sample – name, phone number and email address; location, nearest town, property name; and variety.
NSW > Kevin Moore, NSW DPI, 4 Marsden Park Rd, Calala, NSW 2340 OR
QLD > Sue Thompson, University of Southern Queensland Centre for Crop Health, West Street, Toowoomba Qld 4350.
The disease can then be confirmed and samples lodged with the GRDC National Chickpea Ascochyta project. That project will help determine if the pathogen has change and become more aggressive on varieties with improved resistance. See the media release from GRDC for more information.
If Ascochyta is confirmed, apply a registered fungicide based on chlorothalonil or mancozeb as close as possible to the next rain event.
Why is this happening?
In 2012 and 2013, chickpea Ascochyta was rare in the GRDC Northern region with only 5 cases (all in July/Aug 2013) out of a total of 493 crop inspections. This poses two questions:
Firstly, “why are we seeing so much in 2014?” The Ascochyta pathogen can only survive in seed, on chickpea residue or volunteer chickpea plants. Volunteer plants have been found in 2014 wheat crops with Ascochyta which makes volunteers the most likely source of primary inoculum. There have been at least four post emergent rain events on the crops where the disease has been detected which means four potential infection cycles.
The second question is “why are we seeing so much Ascochyta on HatTrick?” The answer to that is more elusive but we do know that the chickpea seed industry does have varietal purity issues