Suspect barley samples needed

Image of Net Blotch on a leaf

Southern WA barley growers have been asked to monitor crops for net type net blotch this season.

PHOTO: DAFWA

Barley growers in the Great Southern and South Coast regions of Western Australia are urged to test plants suspected of having net type net blotch (NTNB) this season to help confirm a new pathotype of this fungal disease.

The Department of Agriculture and Food, WA (DAFWA) is conducting GRDC-funded research to verify information about NTNB pathotypes and is seeking samples of infected plant material.

DAFWA pathologists are also contributing to a national NTNB survey being conducted through the Queensland Department of Agriculture and Fisheries.

Limited surveys were carried out by DAFWA in 2015 that showed, in glasshouse trials, a range of variety responses to NTNB samples from affected crops and trials.

DAFWA plant pathologist Geoff Thomas says evidence of new disease pathotypes was discovered in 2015, mainly in the Albany and Esperance regions and primarily affecting Oxford feed barley.

“In the past few years, NTNB pathotypes have been relatively stable in WA and variety responses to the disease have been consistent,” he says.

“But tests of last season’s samples and the recent increased susceptibility in Oxford barley indicates that there could be some variability in pathotypes.

Suspect barley leaf material

Any barley leaf material suspected to be infected with NTNB should be sent to:
Jason Bradley, DAFWA, Locked Bag 4, Bentley Delivery Centre WA, 6983.

“There is also anecdotal evidence of potential regional differences in pathotypes and some barley varieties may perform differently than expected this season.”

The newly discovered pathotype affecting Oxford barley in WA appears to be the Skiff virulent pathotype, which is present in eastern Australia.

Seedling tests conducted by fellow DAFWA/Murdoch University pathologists Sanjiv Gupta and Jason Bradley indicated that other varieties that may also be more susceptible to NTNB include Hindmarsh, La Trobe, Scope CL and, possibly, Rosalind.

Geoff says NTNB is a stubble-borne fungal foliar disease that can reduce grain yields and quality and is most prevalent in medium-to-high rainfall areas.

He says the disease is characterised by lesions with net-like symptoms leading to blotched, yellowing and dead leaves, which are generally evenly distributed across the crop.

A range of foliar fungicides that contain triazole and/or strobilurin active ingredients are available to treat NTNB effectively.

“Employing good fungicide-resistance management strategies is essential,” Geoff says.

“This is especially important given that the Curtin University-based Centre for Crop and Disease Management has reported the discovery of a population of NTNB resistant to the triazole fungicide tebuconazole.”

More information:

Jason Bradley,
08 9368 3982,
jason.bradley@agric.wa.gov.au

Geoff Thomas,
08 9368 3262,
geoff.thomas@agric.wa.net.au

Sanjiv Gupta,
08 9368 3622,
s.gupta@murdoch.edu.au

Useful resources:

DAFWA NTNB information (search ‘barley variety fact sheets’ and

‘net type net blotch’)

End of Ground Cover issue 123 July–August 2016
Read the accompanying Ground Cover Supplement:

'More Profit from Crop Nutrition II'

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