AUSTRALIA - A new GRDC fact sheet is aimed at helping growers in the southern grain-growing region prevent grain losses caused by the fungal disease barley scald, writes Rebecca Barr.
Scald can cause losses as high as 50 per cent, with symptoms first appearing as blue, water-soaked lesions that turn to a grey-green colour before developing into elongated bleached blotches with dark-brown ‘scalded’ edges.
The most common source of infection is infected barley stubble, with airborne spore release early in the season thought to spread the disease onto new crops.
Victorian Department of Environment and Primary Industries (DEPI) research scientist Dr Mark McLean says scald affects plants by causing lesions on the leaves. These can lead to defoliation.
“If resistant varieties are not an option, there are several chemical options available to control barley scald, including seed, fertiliser and foliar options,” Dr McLean says.
“Two applications – either seed or fertiliser followed by foliar, or two foliar applications – have been shown to provide good control when disease pressure is high.
“Growers should avoid using the same fungicide active ingredient more than once in a growing season and should always follow label guidelines to ensure maximum residue limits are adhered to at all times.”
While Dr McLean does not think there is a particularly high risk of scald in the southern region this spring, he warns against complacency.
“Barley scald thrives in cool and wet conditions, but it’s not forecast to be significantly wet this year so the risk is less,” he says. “However, if the forecast changes and conditions do favour scald, growers may be caught off-guard. There’s lots of inoculum around, so anywhere there’s barley stubble from susceptible varieties there’s potential for infection; it all depends on the seasonal conditions.
“Scald was not a problem in 2013, due to a late start to the season and generally unfavourable weather conditions, which meant that there was not a large number of serious scald cases.”
Dr McLean is keen to see growers take a proactive approach to this disease by using an up-to-date cereal disease guide to select resistant varieties for next year.
“Scald is a particularly variable pathogen, meaning varietal resistances change over time. New guides are released by the state primary industry departments each year, and can be found on the relevant authorities’ websites, or on the National Variety Trials website.”
A fact sheet on barley scald is available by clicking here.
Photo courtesy of Hugh Wallwork, SARDITheCropSite News Desk