Septoria avenae blotch in oats
- Highbury
Research officer Kylie Chambers (DPIRD) has reported finding very-low levels of septoria avenae blotch in a DPIRD oat trial near Highbury. The disease was found on all varieties in the trial; Carrolup, Bannister, Brusher, Williams, Korabup, Mulgara, Wintaroo and Yallara. The oats had been sown into oat stubble and were at two leaf stage.
Septoria avenae blotch symptoms can appear as brown to purple spots on leaves developing into light and dark brown blotches, with dark brown centres. They are restricted and distinct at first but may enlarge to cover most of the leaf.
Infected stubble is the main source of carryover infection from one season to another. The sexual stage of the fungus Phaeosphaeria avenaria occurs on infected stubble and produces ascospores which are spread moderate distances by wind and are the source of infection in new crops. In consecutive oat rotations where stubble is not destroyed ascospores land on the new crop in large quantities resulting in the development of earlier and more severe outbreaks than in rotation crops.
Septoria avenae blotch can be minimised by avoiding continuous oat cropping but under high disease pressure, such as continuous oat crops, and in favourable environments foliar fungicides can be utilised to reduce disease severity and reduce potential disease losses.
Trials carried out in 2014 by Ashton Gray (formerly ConsultAg) showed that application of registered fungicide as a single spray at flag leaf or multiple sprays at stem extension and again at flag leaf could result in significant yield increase in the susceptible variety Bannister sown onto oat stubble. For further reading refer to the Best practice fungicide management for Bannister oats in the medium and high rainfall zones of Western Australia Crop Updates paper.
For a list of registered fungicides to use as foliar sprays visit DPIRD’s Registered foliar fungicides for cereals in Western Australia page.
More information visit DPIRD’s Diagnosing septoria avenae blotch in oats and Oats: leaf diseases pages.
For more information contact Geoff Thomas, Plant Pathologist, South Perth on +61 (0)8 9368 3262 or Kylie Chambers, Plant Pathologist, Northam on +61 (0)8 9690 2151.