All chickpea crops in Victoria and South Australia will need to be closely monitored this year for Ascochyta blight (AB) infection because all current varieties are now rated as either susceptible or moderately susceptible to infection.
A virulence change in the AB pathogen of chickpeas has occurred, with severe AB infection detected in previously resistant chickpea varieties across both states in 2015 and 2016.
South Australian Research and Development Institute pulse pathology principal research scientist Jenny Davidson said while AB infection was more severe in high and medium rainfall zones, effective disease control strategies were also required in low rainfall regions because severe disease outbreaks could occur in these environments during wet seasons, as was the case in 2016.
‘‘Moderately susceptible varieties will generally require three to four strategic fungicide sprays ahead of rain events, offering two to three weeks of protection, starting at six to eight weeks post-sowing,’’ said Dr Davidson, whose research is supported by the Grains Research and Development Corporation.
‘‘And susceptible varieties will require regular fungicide sprays every two to three weeks throughout the growing season in front of rainfall events.’’
As the pods of all commercial varieties were susceptible to AB, Dr Davidson said they would also require fungicide sprays during pod setting ahead of rain fronts to protect the pods from seed staining and seed abortion.
Agriculture Victoria pulse agronomist Jason Brand said growers also needed to factor into their 2017 management strategies the impact of early sowing following recent rainfall throughout SA and Victoria, as rapid early growth could lead to a greater risk of AB infection.
Dr Brand, leader of the GRDC Southern Pulse Agronomy program investment, said while outbreaks of AB were significant in Victorian chickpea trials last year, crops generally recovered well from the disease once conditions dried out.
He said the AB pathogen would survive on stubble and organic matter for a number of years, so growers must observe a minimum three-year rotation between chickpeas in the same paddock, and avoid planting adjacent to the previous year’s chickpea stubble.