Net blotch in barley
Matthew Willis (Elders) has reported finding spot type net blotch (STNB) in a two leaf Spartacus CL barley crop near Trayning. The disease was widespread across the paddock. This crop was sown onto barley stubble and the seed dressing applied is not registered to provide systemic protection against STNB. The paddock will be monitored.
STNB lesions develop as small circular or oval dark brown spots with yellow edges. Infections can occur following around six hours of leaf wetness at temperatures between 10-25°C. Primary inoculum comes from airborne spores, which are produced on stubbles from previous crops. Risk of infection in seedling to tillering growth stages is greatest in barley regrowth and continuous barley which are exposed to infected barley stubble.
Barley varieties that are susceptible to STNB, such as Spartacus CL, that have not been treated with a registered seed dressing against STNB and are sown into in a high risk situation (barley on barley) are particularly vulnerable. Spartacus CL is susceptible to very susceptible (SVS) to STNB as a seedling and adult plant. To see what other barley varieties are susceptible to STNB refer to DAFWA’s 2017 Barley variety sowing guide for Western Australia.
Growers can consider using a registered fungicide product against STNB, when carrying out post emergent herbicide spraying as plants approach stem extension. Further spraying may be necessary depending on how the season progress. For more information refer to DAFWA’s Registered foliar fungicides for cereals in Western Australia.
For further information on symptoms and management of STNB see DAFWA’s Managing spot type net blotch in continuous barley.