Variety evaluation boost

Crop disease screening capacity of new varieties ramped-up


National Variety Trials
Dr Grant Hollaway is leading a program to significantly increase Australias crop disease-screening capability. PHOTO Brad Collis

Dr Grant Hollaway is leading a program to significantly increase Australias crop disease-screening capability. PHOTO Brad Collis

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More wheat, barley and oat germplasm than ever undergoes testing in disease nurseries.

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Capacity to screen cereals for susceptibility to 10 problematic foliar diseases has reached an all-time record through a program that also informs disease ratings for the National Variety Trials (NVT).

Led by Dr Grant Hollaway, of Agriculture Victoria, and with GRDC investment, the program had 55,000 new varieties and advanced breeding material growing in disease nurseries during 2018, primarily at the six hectares site at the Grains Innovation Park in Horsham, Victoria.

The disease-screening service covers wheat, barley, triticale and, the newest inclusion, oats.

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Sowing of the trials starts in May and ends at the end of August, depending on the target disease.

Dr Hollaway says capacity was increased in recent years to better meet the needs of breeders and the grains industry.

The expansion has been underlined by the purchase of a purpose-built precision plot seeder. It allows the cereal pathology team to sow 3000 individual rows an hour, with each row representing a unique breeding line.

We have also increased the number of diseases we are working on, Dr Hollaway says.

In 2018 we tested for 10 of the most commercially relevant foliar diseases of cereals.

"In addition, we aim to make the assessment as relevant as possible to conditions encountered in the paddock.

"For example, a lot of our inoculum is field-generated, or derived from stubble, so it reflects what is happening commercially.

This calibre of innovation is essential given the devastating impacts possible, especially when pathogens evolve new virulence. - Agriculture Victoria's Dr Grant Hollaway

The foliar diseases targeted in wheat are: stripe rust, leaf rust, stem rust, yellow leaf spot and Septoria tritici blotch.

In barley they are: spot form of net blotch, net form of net blotch, scald and leaf rust. Recently added is red leather leaf in oats.

The disease arms race

With disease pathogens always evolving new forms of virulence, each year sees different issues rise to the fore for special attention.

For Dr Hollaway, of particular interest is the fate of a new rust strain first detected in 2017.

One of the things we are watching with great interest is whether the new stripe rust strain has survived into 2018 and whether it has become important commercially, Dr Hollaway says.

Impacts from this work are particularly stark for commercial breeding companies.

Australian Grain Technologies (AGT) wheat breeder Dr James Edwards says that the continuous improvement undertaken by Dr Hollaway is essential to closing performance gaps in the development of new varieties.

Especially noteworthy in recent seasons, he says, has been the establishment of a Septoria nursery in Hamilton, Victoria, in response to the re-emergence of this disease after a greater than 20 year absence.

He also points to innovation within the rust nurseries.

The wheat breeding companies are all extremely grateful for the great work done by Grant and his team, Dr Edwards says.

A few seasons ago they set out to establish a reliable nursery to screen for stem rust.

"They have developed systems that in the 2017 season resulted in an excellent stem rust nursery.

"They also manage the only disease nursery in the southern region, where we have reliably had stripe rust over the past three seasons.

This calibre of innovation is essential given the devastating impacts possible, especially when pathogens evolve new virulence.

Overall, Dr Hollaway says he is seeing ongoing improvement in the disease resistance profile of new cereal, varieties, but there is never room for complacency.

It's a challenging space, he says.

Breeders take two steps forwards and we go one step backwards because of a variation in the pathogen. Its a complex space to be in, keeping up with pathogen evolution and the surprises that produces.

Focus on oats

A new focus for the Horsham-based team is oats.

Cereal Pathology technical officer Laura Roden is managing the oat pathology trials, which are looking at the impact of red leather leaf on grain and hay yield to determine its economic impact.

The efficacy of various fungicides is also being examined.

The project is in response to increased interest in domestic and export oats and hay markets and includes commercially grown varieties and yet-to-be released varieties.

We will measure disease development during the season and record hay and grain yields of different oat varieties and compare how they performed with and without the presence of the disease, Ms Roden says.

To date, there has not been very much research into red leather leaf and there are no registered fungicides for its control.

Agriculture Victoria oat research is being carried out in collaboration with the South Australian Research and Development Institute and the Western Australian Department of Primary Industries and Regional Development, with investment from GRDC.

GRDC Research Codes DAV00136, DAV00129

More information: Dr Grant Hollaway, grant.hollaway@ecodev.vic.gov.au; Dr James Edwards, james.edwards@agtbreeding.com.au.

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