Net blotch is expected to be at damaging levels in Western Australian barley crops this year, particularly in high rainfall areas, but growers can reduce the risks by adopting an integrated disease management approach.
Department of Agriculture and Food (DAFWA) researcher Kith Jayasena has observed high levels of net-type and spot-type net blotch fungal spores in stubble from 2013 barley crops.
“There is a high risk of damage to 2014 barley crops due to carry-over of the disease from last year, heavy stubble loads and warm conditions forecast for coming months,” he said.
“Both forms of net blotch have become more prevalent in WA in recent years and were damaging last season, particularly in south coastal regions.”
Dr Jayasena will this year conduct new research, funded by the Grains Research and Development Corporation (GRDC), aiming to correlate net-type net blotch infection levels with yield losses in high rainfall, long-season environments.
The large-scale trials investigating WA’s most common form of net blotch will take place this season at South Stirling in the lower Great Southern region.
Dr Jayasena said net blotch was most damaging in paddocks re-sown to barley without a break crop and the fungus was carried from season to season, mainly through infected barley stubble.
“Net blotch can also be seed borne and infected crop seed can introduce the disease to new locations,” he said.
“Barley seed suspected to be infected with net blotch should be treated with registered seed dressings or in-furrow fungicides.”
Growers can reduce the risk of crop losses from net-type and spot-type net blotch by:
- Rotating crops and not seeding barley on barley stubble;
- Avoiding sowing susceptible (S) and very susceptible (VS) varieties, particularly in disease prone environments and if sowing into barley stubble. Barley variety disease rankings are available in the WA Barley Variety Guide for 2013, available by searching this title on www.grdc.com.au;
- Burning stubble to reduce disease carry-over;
- Applying a fungicide spray if required to crops. A second spray may be necessary in high rainfall areas depending on weather conditions. Whenever possible, rotate fungicides with different actives, which will reduce the development of fungicide resistant pathogen populations;
- Applying potassium fertiliser to barley crops deficient in the nutrient six to eight weeks after barley crop emergence. This can reduce the impact of net blotch and other foliar leaf diseases such as powdery mildew.
More information about identifying and managing net blotch and other barley diseases is available at www.agric.wa.gov.au/cropdisease
Caption: Net-type net blotch on Oxford barley in 2013. Photo by Kith Jayasena, DAFWA.
Kith Jayasena, DAFWA
08 9892 8477, 0407 081 388
Natalie Lee, Cox Inall Communications
08 9864 2034, 0427 189 827
GRDC Project Code
West, North, South