Western Australia
April 14, 2016

Net-type net blotch evident in Oxford barley regrowth in the South Stirling area in March, 2016.

Grain growers in Western Australia’s southern cropping areas are encouraged to take early, collective action to help reduce the risk of yield losses due to barley diseases this season.

Department of Agriculture and Food (DAFWA) researcher Kith Jayasena said he had observed high levels of barley leaf rust and barley net-type net blotch (NTNB) in regrowth barley in the Great Southern region.

Dr Jayasena is conducting DAFWA research under a Grains Research and Development Corporation (GRDC) funded project which aims to reduce costs and losses attributed to crop diseases in WA.

He said barley growers would need to pay particular attention to leaf rust and NTNB this season as some barley varieties were more prone to these diseases following a breakdown in resistance to leaf rust in 2013 and detection of new strains of NTNB.

The Centre for Crop and Disease Management (CCDM) also reported last year that it had discovered a population of NTNB resistant to the triazole (DMI) fungicide tebuconazole and some other types of triazole fungicides.

“Strategies that can help minimise the risk of yield losses include destroying the ‘green bridge’ including barley volunteers and weeds (to reduce rust carry-over); using appropriate seeding strategies; monitoring emerging crops for signs of disease; and considering using a registered foliar fungicide if the variety is susceptible to the diseases found,” Dr Jayasena said.

“Seeding strategies include avoiding seeding barley on barley; choosing varieties with good disease resistance; using registered seed dressings or in-furrow fungicides; and avoiding a high seeding rate.”

Following seeding, growers can consider:

• Avoiding high nitrogen rates early in the season which can generate a bigger crop canopy, favourable to disease development
• Applying potassium fertiliser to crops deficient in the nutrient six to eight weeks after crop emergence
• Using foliar fungicides. A list of registered projects is available by searching ‘registered foliar fungicides’ on the DAFWA website www.agric.wa.gov.au.

“I encourage growers to monitor the early development of crops for leaf disease symptoms and to consider using a registered foliar fungicide if the variety is susceptible to the diseases found,” Dr Jayasena said.

“A second spray may be necessary. Whenever possible, rotate fungicides with different actives to reduce the development of fungicide resistant pathogen populations.”

Dr Jayasena is currently conducting studies to determine how new barley varieties with ‘adult plant resistance’ – a relatively durable form of resistance to disease – respond to fungicides to control leaf rust.

More information about barley leaf rust management is available in a GRDC Hot Topic at www.grdc.com.au/BarleyLeafRust, while more information on NTNB can be found on the DAFWA website by searching ‘net blotch’.

Website: http://www.grdc.com.au

Published: April 14, 2016