Crop Watch October 2022

Wheat stripe rust on the move

Wheat stripe rust is now prevalent in every growing region of South Australia. With cool, wet conditions forecast to continue in the short term, conditions will remain conducive for further disease development. In Victoria wheat stripe rust pressure is high and many paddocks are severely affected. South Australian growers should be aware of the Victorian situation and that high inoculum levels are likely moving through SA growing regions. Growers across the state are urged to monitor their paddocks for significant levels of stripe rust and implement fungicide regimes where necessary.

Stripe rust pathotypes

There are multiple pathotypes of wheat stripe rust in Australia and varietal resistance can be pathotype specific. Current reports of varietal responses in South Australia indicate there are multiple pathotypes currently present in the state. Rust pathotyping is conducted through the Australian Cereal Rust Survey at Sydney University. Growers are strongly encouraged to submit samples to the survey either directly or by sending samples to SARDI Cereal Pathology.

Information on adult plant resistance in varieties

Adult plant resistance (APR) is present in most varieties commonly grown in South Australia and will provide some useful resistance past GS32-39. The level of resistance provided by APR genes is captured in a variety's disease rating. Disease can build up at earlier growth stages with susceptible reaction types observed before the APR is effective. As APR does not provide full resistance in most varieties, some disease can still be observed at the adult plant stage, and the variety rating should be used as an indicator of potential infection levels.

Management advice

A decision support app StripeRustWM is available to help growers and advisors make fungicide decisions based on a forecasting model and potential economic returns.

Developed in a collaboration led by the Western Australian Department of Primary Industries and Regional Development, with contributions from Agriculture Victoria and New South Wales Department of Primary Industries and co-investment from the Grains Research and Development Corporation, the app is suitable for wheat growers across Australia.

The app is available for iPads or Android tablets from the relevant app store.

Wheat stripe rust eastern resistance ratings

Predicta B courses

Agronomists wanting to build or refresh their expertise on soil-borne diseases are invited to register for the 2022 PREDICTA B Root Disease Risk Management course, which is returning following a 2-year hiatus due to COVID-19.

The courses will be presented by the SARDI team and feature local experts.

Designed for agronomists with all levels of experience, one-day courses (click to register) are scheduled for

• Adelaide – Register for Tuesday 25 October
• Wagga Wagga – Tuesday 8 November
• Bendigo – Tuesday 15 November
• Horsham – Wednesday 16 November
• Perth – Monday 12 December
• Perth – Tuesday 13 December

Attendance includes accreditation for delivering PREDICTA B, a DNA-based soil testing service that enables the identification of pathogens that pose the greatest risk to farms.

The course will cover

• principal soil-borne diseases
• crop symptoms
• host range
• effects of season
• disease management and soil sampling strategies
• paddock follow-up.

Participants will learn how to interpret and understand PREDICTA B results, as well as use the service to make better informed variety, rotation, and paddock management decisions. Other topics include yield loss risk categories for established tests and population density categories for new tests.

Participants will also learn about the PREDICTA rNod rhizobia testing service, which helps growers and advisers determine if inoculation with rhizobia is likely to be beneficial in faba beans, lentils, vetches, and field peas. PREDICTA rNod was developed through a strategic partnership between the Grains Research and Development Corporation and SARDI.

Registration includes access to

• the PREDICTA B service
• Broadacre Soilborne Disease Manual
• a PREDICTA B soil corer.

More information

Nicole Thompson – Program Leader, Plant Health and Diagnostics, SARDI
Phone: (08) 8429 0915
Email: nicole.thompson@sa.gov.au

See PREDICTA B