Eastern Australia experienced a good cropping year in 1998, with a wet winter and spring in many cropping areas. These conditions favoured the fungal chickpea disease ascochyta, relatively new to Australia and devastated the rapidly expanding, relatively new chickpea industry. All commercially grown varieties were susceptible to it. Was this to be the end of a promising new industry or could future crops be protected?
In NSW, a number of scientists were proactive in addressed this emerging chickpea disease. They also focused on other issues confronting the industry such as, improving grain quality, higher yields and better agronomic type, along with other diseases. Two of these key people were NSW DPI chickpea breeder Dr Ted Knights and plant pathologist Dr Kevin Moore.
Fortunately NSW DPI chickpea breeding had been proactive in addressing ascochyta, with tolerant lines previously brought into the country. Fortunately, this tolerance was already incorporated into advanced breeding material, with varieties with improved resistance released as fast as two years after the 1998 epidemic. First released variety, Howzat, had many favourable attributes of previous susceptible varieties, including desirable seed size, similar yield and good agronomic type.
Since then, several varieties with improved ascochyta tolerance have been released, but new strains of ascochyta have evolved which have altered the tolerance ratings of some varieties. The Australian Chickpea Breeding (CBA) program, now led by Dr Kirsty Hobson, has and is addressing this issue using a variety of resistance genes. These geneses come from multiple sources, including wild chickpea types.
CBA Captain is a recent release from the program. It is an erect desi type, has good plant height, good height to lowest pod and good lodging resistance resulting in improving harvestability. It has broad adaption to the chickpea growing regions across the country. However, like all current varieties, none are sufficiently resistant to ascochyta that fungicide treatments are not required.
With targeted disease management paramount, the roles of pathologists, such as the recently retired senior DPI pathologist Dr Kevin Moore are crucial for the industry.
Penny Heuston, NSW DPI Project Officer, Northern Cropping Systems, in a recent podcast with Dr Moore, highlighted his role in quickly identifying the disease, assessing its widespread occurrence and devising fungicide control strategies.
Ability to successfully manage chickpeas and it's diseases in Australia by a combination of breeding for improved tolerance, fungicides strategies at optimal timings, is illustrated by crop statistics. In 1998, NSW chickpea area was around 63,000ha. Today an average year is closer to 1,000,000 ha, valued at around one billion dollars. In addition the crop provides rotational benefits for following crops, such as adding soil nitrogen and helping reduce cereal diseases like crown rot.
Part of the ascochyta research program led by Kevin Moore, includes sowing seed treated with a thiram-based fungicide. This includes, even with growing varieties with the current best regarded ascochyta resistance, such as CBA Captain, PBA Seamer, PBA Boundary, PBA HatTrick, PBA Slasher and most Genesis varieties.
Dr Moore and colleagues research stresses not to grow chickpeas in paddocks that grew them in the previous year. Removing volunteer chickpea plants infected with ascochyta (in fallows or following crops) is important. Their presence provides inoculum for the following crop, even if volunteer plants are killed with herbicide. Controlling volunteers early limits the amount of inoculum they produce and helps to minimise fungicide sprays in future crops in northern NSW, Dr Moore stresses.
Foliar fungicides as a control measure was part of Dr Moore's research. Their targeted use provides cost-effective ascochyta management in all varieties. The key, Kevin Moore says, is timing. They are most effective when applied as a preventive before rain.
Dr Moore's position has been filled by Hayley Wilson, who spent over a year working with him.
Next week: Best bet herbicides for grain sorghum weed control.
- Bob Freebairn is an agricultural consultant based at Coonabarabran. Email robert.freebairn@bigpond.com or contact (0428) 752 149.
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