Barley loose smut has been widely reported across Victoria this year. Affected plants are found with black heads which disperse spores and appear to ‘disintegrate’. Higher than average rainfall at flowering during 2022 likely favoured the infection of barley heads, contaminating harvested grain.
Loose smut can be prevented effectively through the regular use of clean seed and seed treatments. Ensuring good seed coverage is important when using seed treatments to control loose smut effectively. Poorly treated seed can often carry infection into the crop next season.
The use of foliar fungicides in crop to control the disease is ineffective to prevent infected heads emerging during the season, however, a single foliar application can help reduce the carryover of infection into next year’s crop. This means that foliar fungicides can be effective when used to treat paddocks where growers wish to retain seed for sowing. See the paper ‘A new approach to managing loose smut on barley’ for details on trials that have used this approach. Please note that there are currently no foliar fungicides registered for loose smut control and the level of efficacy cannot be assured by the registrant. All label directions must be followed relating to the rate and application timing and withholding periods. When using fungicides at late foliar stages, the withholding period to harvest must be followed to avoid residue violations in delivered grain.
Please see Off label chemical use on the AgVic website for more information regarding off label chemical use. Please note the minimum withholding period of the product when using fungicides at late foliar stages.
Further information on loose smut can be found in Barley loose smut in the Wimmera and Mallee 2023.
The Department of Primary Industries and Region Development in WA also has some useful resources:
For more detailed seed treatment advice the Ground Cover article New advice for dealing with fungal disease in WA crops in season 2019 provides an excellent overview of the relative effectiveness of different seed treatments.
Other Disease Updates
Wheat
Stripe rust – Several crops, particularly those susceptible to pathotype “239” (e.g., Scepter) have been observed with infections on the flag leaf and some in the head. Depending on the variety resistance and yield potential, foliar applications (“head wash”) can be considered if the crops are in head emergence but once crops are past flowering and into grain fill there is little benefit in applying fungicides for further control.
Septoria tritici blotch – Dry weather is expected to reduce septoria severity and with it reduce yield losses. Where susceptible varieties (eg: Scepter or Razor CL Plus) are grown and high disease severity persists, a foliar application at head emergence may be beneficial to provide further control of the disease.
Crown rot – watch for deadheads (whiteheads) in wheat this year. Paddocks that have high levels of crown rot during 2023 will need to be managed for 2024. Fusarium head blight (FHB) infection found during 2022 was mainly caused by crown rot pathogens. Where the infected seed was sown, the risk from crown rot is likely to be high.
Fungicide Resistance
Net form of net blotch – please note that fungicide resistance to Group 7 (SDHI) was detected in South Australia during 2021. If this resistance has spread to Victoria, then seed dressings containing fluxapyroxad and other Group 7 fungicides will have lost their efficacy. If you have noticed field failure of any of these chemicals, please contact the Horsham Field Crops Pathology Team or send in samples for fungicide resistance testing.
If you see any other fungicides (across all cereals or pulses) that are not giving the level of control expected please contact us so that we can follow up any potential field failures.
Pulses
Crops will need to be monitored for Ascochyta blight and Botrytis grey mould (BGM) and fungicides applied where appropriate. This includes protecting pods and the seed which are susceptible to disease.
Soil-borne disease – patches in pulse crops, particularly lentils, are being reported. As the weather warms up and plants need to draw more moisture from the soil, root diseases will become more apparent. A range of pathogens are thought to be causing these symptoms. If you suspect, you have soil-borne disease in a lentil crop you can contact the Horsham Field Crops Pathology Team.
The team is also looking for paddocks to survey within an hour’s drive of Horsham. If you have a pulse crop that has soil-borne disease symptoms, please contact Chloe Findlay [email protected]
Sclerotinia – The Horsham team are also looking to survey paddocks with sclerotinia in lentil and lupin. If you suspect that you or your grower have sclerotinia in their crop, please contact Chloe [email protected]
For management information about sclerotinia please see the article Sclerotinia in Victorian Pulses.
Further Information
Further information on field crop disease can be found in the online Identification & Management of Field Crop Diseases in Victoria manual.
