There is a heightened risk of stripe rust and Septoria tritici blotch (STB) in wheat this year and varieties rated susceptible need to be monitored with a view to timely fungicide applications.

Early stripe rust infections have been present in volunteer crops since April and STB was found in wheat in the Wimmera at the end of May.

Disease detections this early in the season confirm the high disease pressure forecast for this year, however, conditions in spring will determine the severity, and potential yield losses associated with disease.

Despite the forecast for drier than average conditions later in the season, growers and advisors are encouraged to inspect these crops and monitor them with a view to timely fungicide application if warranted. Keeping in mind that the amount of rain/moisture needed for crop diseases to develop and spread can be low. Six hours of leaf wetness can be enough to drive infection in crops.

A current copy of the cereal and pulse disease guides are available from Apple Books (just search ‘Victorian disease guide’ in the Apple Book store) or the AgVic website, Pulse disease guide or Cereal disease guide to assist with disease management strategies during the season.

Stripe rust
Relatively early reports of stripe rust were expected given the widespread green bridge across eastern Australia this season. The early detection indicates that stripe rust will be common across Victoria and proactive management will be required in susceptible varieties to avoid losses. Stripe rust identification, management, and epidemiology can be found in ‘Identification & Management of Field Crop Diseases in Victoria’.

Growers and advisors are encouraged to adopt a three-step approach to assess stripe rust infection.

1. Review variety ratings using a current cereal disease guide to ensure the ratings are current. Do not use last year’s ratings. The current Victorian guide can be found here.
2. Monitor crops closely.
3. Use the StripeRustWM app to support decision making. The app is now available for phones as well as tablets. The app can be downloaded from the Apple and Google Play stores. A user guide is also attached for those unfamiliar with the app.

Septoria tritici blotch
Above average rainfall during spring 2022 resulted in increased biomass of cereal crops in Victoria which in turn left higher stubble loads after harvest. Since stubble is the primary source of STB inoculum, the risk in 2023 is very high where wheat is sown into wheat stubble or close to wheat stubble. With early infections of STB detected in the Wimmera, growers are encouraged to follow the steps below to manage STB during 2023 season.

1. Review variety ratings using a current cereal disease guide, to ensure the ratings are current. Do not use last year’s ratings. The current Victorian guide can be found here.
2. Where susceptible varieties are sown, monitor crops closely by looking at leaves low on the plant or canopy. If symptoms appear and conditions are conducive, consider applying a foliar fungicide at stem elongation (Z31) to reduce the spread onto the upper canopy.
3. STB spread on to the upper canopy will heavily depend on spring conditions, if a wet spring is expected, crops should be protected through application of foliar fungicides at flag leaf emergence (Z39) and at mid-flowering (Z55) depending on the level of infection.
4. It is also worth noting that the STB fungal population has the potential to develop resistance to fungicides and unnecessary use of them should be avoided. Visit afren.com.au for latest information.

For further information on STB and diagnostic details visit: Septoria Leaf Blotch of Wheat – Field Crop Diseases Victoria

Upcoming Events – all upcoming events can be found on Field Crop Diseases Vic under Upcoming Events

Field crops pathology field day – early season disease update
This field day will aim to cover the issues that are emerging and the issues to keep an eye on after last year’s high disease load.
When: Wed July 19th @ 9:00am – 12 noon
Where: Horsham
Register here

Field crops pathology field day – mid season disease update
When: Thurs Oct 5th @ 9:00am – 12 noon
Where: Horsham

Southern Pulse Agronomy field day
When: Thurs Oct 19th
Where: Dooen

Further information
Further information on these and other field crop disease can be found in the online Identification & Management of Field Crop Diseases in Victoria manual.

Horsham Field Crop Diseases research group (Agriculture Victoria)
For further information and assistance in diagnosing field crop diseases, contact the Horsham Field Crop Diseases research group.
Ph: (03) 5450 8301
Email: [email protected]