Investment

Wheat powdery mildew is a sporadic disease that can cause up to 25% yield loss in conducive conditions. In the Southern region, Wheat powdery mildew (WPM) has increased in prevalence, with reported incidence and severity particularly high in areas of the Yorke Peninsula, Lower North, Eyre Peninsula and South-east of South Australia and the North-east of Victoria in 2021.

Shifts in fungicide sensitivity and resistance to both Group 3 (DMI) and Group 11 (QoI) fungicides have been detected in WPM in the Southern Region. Resistance to the Group 3 (DMI) fungicides, propiconazole and tebuconazole, has been detected in NSW and Vic, with frequencies ranging from 50 to 100% of in-field samples while lab detection of reduced sensitivity has been identified in samples from SA and Vic. Fungicide resistance to all Group 11 (QoI) fungicides in WPM was first detected in-field in NSW, SA, Tas and Vic Australia in 2019. Detection of fungicide resistance indicates potential inefficacy of these fungicide groups / modes of action when applied in crop to control WPM. There are limited registered products for WPM management in the remaining fungicide Group 7 (SDHI) which has not yet had reduced sensitivity to WPM detected. It is critical that fungicide resistance management strategies are developed, and implemented, to prevent further loss or reduced efficacy of the fungicide options available to manage this disease.

During 2020 and 2021, Trengove Consulting conducted field trials (SAGIT TC120) that developed fungicide resistance management strategies for WPM. This project highlighted the effectiveness of varietal resistance and the optimal variety by fungicide application strategies as measured by yield gain.

This investment will conduct validation trials in the Yorke Peninsula, Upper SE (SA) and NE (VIC) that address wheat varietal resistance, pre and post emergent fungicide efficacy, water and fungicide rates. Testing and analysis will be conducted by Centre for Crop Disease Management (CCDM). The investment will also include a regional paddock survey of the Yorke Peninsula, Upper SE and NE Vic. Outcomes of this project will be extended through local grower group field walks and GRDC Research Updates in the Southern region.