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Stem rust found in oat volunteers in Wagin

  • Wagin

A close up photo of stem rust on an oat volunteer plant
Stem rust on an oat volunteer plant. Photo courtesy of: Wade Longmuir (Alexander Galt)

Wade Longmuir (Alexander Galt) has reported severe stem rust in oat volunteers west of Wagin.

Stem rust can be identified by large reddish-brown pustules, oval or elongated in shape, on stems and sometimes both sides of leaves and leaf sheaths in oats. In severe cases, heads also become infected resulting in significant crop losses. Oat stem rust will not attack wheat.

Plant pathologist Geoff Thomas suggests that the presence of rust infected regrowth is a timely warning that other oat volunteers may be carrying rust inoculum and could act as a source of infection for sown susceptible oat varieties as the season progresses. Cereal rusts, particularly stem rust, can develop rapidly as temperatures become warmer in late winter into spring.

Reducing potential inoculum sources by removing oat volunteers is still an important step in trying to delay onset of rust in crops this season. Monitoring oat crops for the presence of both leaf and stem rust is highly recommended and, where appropriate, application of registered fungicide to infected susceptible crops, before infection becomes severe, will reduce the impact of rust. For information on registered foliar fungicides see the visit the department’s Registered foliar fungicides for cereals in Western Australia.

It is important that samples of all rusts are sent for pathotype testing which is a free service. Infected leaf samples should be mailed in paper envelopes (do not use plastic wrapping or plastic lined packages) along with your details and collection information (location, variety etcetera) directly to the Australian Rust Survey, Reply Paid 88076, Narellan NSW 2567. Free reply paid envelopes can be ordered from the University of Sydney.

For further details see the University of Sydney's Cereal Rust website and How to prepare and send samples for dispatch to the Australian Cereal Rust Survey.

For further information including description of symptoms visit the department’s Diagnosing stem rust in oats and Oats: leaf diseases pages.

For more information contact Geoff Thomas, Research Officer, South Perth on +61 (0)8 9368 3982.