Ongoing vigilance urged for endemic chickpea disease
GroundCover™ Issue: 103 | Author: Tom Dixon
While all the indicators suggest a good year for growing chickpeas in northern Australia, plant pathologists and breeders still flag caution to growers about the disease ascochyta blight – a fungal disease endemic in all chickpea growing regions in Australia.
Their reservations stem from the likelihood that growers in central Queensland may be harbouring ascochyta blight in 2012 stubble.
Dr Malcolm Ryley, principal plant pathologist and summer crops pathology team leader for Agri-Science Queensland, says: “Vigilance should be maintained and the specific recommendations for management of ascochyta blight need to be followed.”
“During the 2012 season in southern Queensland there were very few reports of ascochyta blight, but in the central highlands region of central Queensland there were serious widespread outbreaks during July due to a series of significant rainfall events.
“In central Queensland all of the commercial varieties are susceptible, or highly susceptible, to ascochyta blight and the outbreak early in the 2012 season means that there will be infected chickpea stubble in paddocks,” Dr Ryley says.
As global demand for grain protein crops increases and varieties with improved ascochyta blight resistance are being developed, the number of growers cropping chickpeas is on the increase nationally.
A record 563,000 hectares of chickpeas were grown nationwide in 2012, of which almost 500,000ha were sown as winter crops in northern Australia. In 2010 546,000ha of chickpeas were planted nationally, but waterlogging and major outbreaks of ascochyta blight and botrytis grey mould unfortunately devastated the year.
Dr Kristy Hobson, leader of the Pulse Breeding Australia chickpea program, says the increase in chickpea cropping is due to a combination of factors.
“In more recent years, chickpeas have had a relative price advantage over cereals and this has provided a financial incentive for growers to include or expand their chickpea area. This is particularly the case in northern Australia where there are few alternative winter crop options,” Dr Hobson says.
This, plus improved varieties with increased disease resistance and associated management, an overriding need for Australian growers to source cheaper and more reliable forms of nitrogen, and the need to introduce a break crop in cereal rotations are reasons why the number of chickpea crops has increased.
Senior industry development manager for Pulse Australia Gordon Cumming says the ascochyta fungus survives and spreads in four ways: infected seed; infected chickpea stubble; infected volunteer chickpea plants; and raindrop splash during the growing season.
“During rain events, when raindrops hit an ascochyta lesion on the leaf or stem of an infected plant, spores are spread to other parts of the plant and to nearby plants,” Mr Cumming says.
“Large-scale weather patterns will not necessarily correlate with the spread of the disease from one region to another, unlike other crop diseases such as cereal rust.”
Mr Cumming says variety choice plays a major role in managing the disease and suggests planting varieties with greater ascochyta resistance, including PBA HatTrick or PBA Boundary, in northern New South Wales and southern Queensland.The two have similar resistance levels to ascochyta blight, but PBA HatTrick has better resistance to phytophthora root rot.
“Varieties suited to central Queensland are different to those in northern NSW and southern Queensland, and all are susceptible to ascochyta blight,” Mr Cumming says.
Kyabra, Moti and PBA Pistol are the dominant varieties suited to central Queensland. However, Dr Hobson says it is not likely there will be a resistant variety for Central Queensland for another four years.
Dr Ryley says ascochyta management recommendations for 2013 in central Queensland will be similar to those for susceptible varieties in southern Queensland.
“That is, not planting in or adjacent to paddocks where chickpeas have been grown in the past three seasons, particularly if ascochyta was found in those crops. Only grow varieties that are adapted to central Queensland. Use clean, fungicide-treated seed sourced from central Queensland, and apply a preventive foliar spray of a registered fungicide before the first rainfall event after emergence, three weeks after emergence, or at the three-branch stage – whichever comes first,” Dr Ryley says.
Dr Malcolm Ryley
07 4688 1316
Dr Kristy Hobson
02 6763 1174
0408 923 474
GRDC Project Code DAQ00154