Assessing the risk of Fusarium crown rot in 2025

Key messages

• Consecutive good seasons, stubble retention and tight cereal rotations have likely favoured a build-up of Fusarium crown rot across the Riverine Plains, with its prevalence confirmed by testing in 2024
• Crown rot can cause yield losses of 5 to over 20 percent in wheat, with greater losses in seasons with a dry finish
• Now is an ideal time to assess the risk for this season’s crops by sampling last years’ cereal stubble or by using Predicta®B DNA soil testing
• A Riverine Plains project demonstration site sown to wheat for two years (2021-2022), had high levels of the disease — in this case, burning the wheat stubble and planting faba beans in 2023 reduced levels to low within 12 months 

The extent and impact of Fusarium crown rot remains largely unrecognised by cereal growers in the Riverine Plains. This is despite an increase in the disease locally, as confirmed by surveillance and test results conducted by the NSW Department of Primary Industries.

So what do farmers need to know about assessing and reducing the risk of yield loss in cereals ahead of the 2025 season?

What is it?

Fusarium crown rot is a fungus that can survive for several seasons in cereal stubbles and grass weed residues. In stubble-retained systems spores can be spread across paddocks when stubble is slashed, incorporated or grazed, which can then infect new cereal crops.

During a tight spring with heat stress, Fusarium crown rot fungi restrict the flow of water and nutrients to developing heads, which can result in pinched grain or heads with no grain. This can lead to “whiteheads” in the crop, but these don’t always occur reliably and can be confused with frost, mice or insect damage and moisture stress. 

The disease causes yield loss of 5 to over 20 percent in cereals and can also impact grain quality. Durum wheat losses can be over 50 percent and are often greater than losses from Fusarium crown rot in bread wheat or barley. 

Assessing the risk 

In recent years, we’ve not seen the typical “white heads” appearing at grain fill, which indicates that Fusarium crown rot is present in paddocks. This may be due to a run of favourable springs, which can reduce the impact of the disease. However, the run of wet seasons will have also favoured disease build up and survival, so Fusarium crown rot is likely to be widespread across the Riverine Plains.

Given the lack of white heads, it’s probable that many farmers in the Riverine Plains are unaware of the presence of the disease in their paddocks, or of its potential to build up and cause damage under drier conditions during grain fill. 

Given seasonal conditions have been conducive to Fusarium crown rot build-up and survival, a stubble test or Predicta B DNA soil test is highly recommended to determine the level of risk, especially when cereal rotations are tight. Both tests only take a few weeks to return results and are an easy and relatively inexpensive way to confirm the presence of the disease and the risk of yield loss. An advantage of Predicta B DNA soil testing is that it can also test for other diseases, like Take-all and Rhizoctonia, which are likely to reduce yield. It’s recommended samples are collected and sent for testing in late summer; this will ensure results are available well ahead of sowing to inform management decisions. 

If testing indicates a high level of risk, there are a number of strategies farmers can use to reduce the risk of yield loss including cereal choice, break crops, nutrition, stubble management and inter-row sowing. Learn more about signs of Fusarium crown rot and strategies for minimising yield loss. 

What we found – Riverine Plains and GRDC project results

As part of a GRDC project investment, Riverine Plains is investigating how stubble management strategies, soil acidity and break crops can impact Fusarium crown rot pathogen levels over time.

Fourteen farmer paddocks were sampled across the Riverine Plains region during February 2024 using Predicta B soil testing, as well as for soil pH. These results showed that 79% of these paddocks, which were to be sown to wheat in 2024, had medium to high levels of Fusarium crown rot, while 14% were considered at low risk and 7% were below the level of detection. 

During January 2023, several treatments at a Riverine Plains stubble management demonstration site at Murchison were tested using stubble plating techniques provided by NSW DPI for Fusarium crown rot, following two years of wheat crops. The results indicated a high risk of Fusarium crown rot across these treatments, and in an effort to reduce disease levels, the wheat stubble was burnt and the paddock was sown to faba beans in 2023. Follow-up Predicta B risk assessments in 2024 showed that these practices successfully reduced Fusarium crown rot levels to low for all the stubble management treatments. 

These results highlight the benefits of understanding Fusarium crown rot risk in the Riverine Plains. Learn more about our 2023 project trial outcomes.

Next steps

Using tests such as Predicta B or collecting stubble for analysis can help understand the risk of yield loss, allowing management strategies to be put in place in high-risk situations. 

If you'd like your paddock assessed for Fusarium crown rot risk before sowing in 2025, you can use Predicta® B sampling (contact your agronomist to arrange testing for a fee). Alternatively, a free cereal stubble testing service is provided by the NSW Department of Primary Industries (NSW DPI); please email Sabita Duwal, Riverine Plains Project Support Officer, to arrange bags and sample collection (sample bags are also available at LLS offices across NSW).  

Acknowledgements 

This article was produced as part of a GRDC National Grower Network investment in the Understanding the link between cereal stubble, subsurface acidity and crown rot project. 

The free stubble testing by NSW DPI is provided via a co-investment with GRDC and uses a stubble plating method.

Further reading

GRDC Southern Crown rot factsheet
Preventing fusarium crown rot from reducing cereal yields